hello I moved and dropped my radio. Its a wards airline. Tubes are 25z5, 43, 6d6, 6d6, 6c6. My guess is the resistor on the back that is long, flat, and rectangular has opened up. What should I replace this with? Can I just substitute a resistor of approximate wattage and ohmage to drop 45 or so volts

I forgot to add that I tested the tubes and they all work on my tester
:hello I moved and dropped my radio. Its a wards airline. Tubes are 25z5, 43, 6d6, 6d6, 6c6. My guess is the resistor on the back that is long, flat, and rectangular has opened up. What should I replace this with? Can I just substitute a resistor of approximate wattage and ohmage to drop 45 or so volts

:I forgot to add that I tested the tubes and they all work on my tester
::hello I moved and dropped my radio. Its a wards airline. Tubes are 25z5, 43, 6d6, 6d6, 6c6. My guess is the resistor on the back that is long, flat, and rectangular has opened up. What should I replace this with? Can I just substitute a resistor of approximate wattage and ohmage to drop 45 or so volts
Hi Sean
This is a Wire Wound Resistor, as long as you replace it with one of the same value type and wattage you should be fine, in other words it does not have to be a flat type.

Mark

:so do I go by tube heater current in calculating approximate ohmage to get voltage drop, or try and measure the open resistor

::I forgot to add that I tested the tubes and they all work on my tester
:::hello I moved and dropped my radio. Its a wards airline. Tubes are 25z5, 43, 6d6, 6d6, 6c6. My guess is the resistor on the back that is long, flat, and rectangular has opened up. What should I replace this with? Can I just substitute a resistor of approximate wattage and ohmage to drop 45 or so volts
:Hi Sean
: This is a Wire Wound Resistor, as long as you replace it with one of the same value type and wattage you should be fine, in other words it does not have to be a flat type.
:
:Mark
:

Hello I must also add that there is no isolation transformer in this set, and tubes heaters or filaments are in series
:I forgot to add that I tested the tubes and they all work on my tester
::hello I moved and dropped my radio. Its a wards airline. Tubes are 25z5, 43, 6d6, 6d6, 6c6. My guess is the resistor on the back that is long, flat, and rectangular has opened up. What should I replace this with? Can I just substitute a resistor of approximate wattage and ohmage to drop 45 or so volts

:Hello I must also add that there is no isolation transformer in this set, and tubes heaters or filaments are in series
::I forgot to add that I tested the tubes and they all work on my tester
:::hello I moved and dropped my radio. Its a wards airline. Tubes are 25z5, 43, 6d6, 6d6, 6c6. My guess is the resistor on the back that is long, flat, and rectangular has opened up. What should I replace this with? Can I just substitute a resistor of approximate wattage and ohmage to drop 45 or so volts
Hi Sean
I assume, without looking at the schematic for this radio, that since the filaments are all in series that this resistor is also in series with the filament string, which would mean it is being used as a ballast resisitor, as long as you use a Wire Wound Resistor of the same value and wattage you will be ok.
Mark

:Yes the filaments are in series so finguring out what the resistance and wattage is the issue. dont think I can measure the resistor since its open. If I go for a 46 volt drop then resistance would be 155 ohms at 14 watts........dont even know if I have anything close, .....might have to put several resistors in series to get that value and not burn them up

::Hello I must also add that there is no isolation transformer in this set, and tubes heaters or filaments are in series
:::I forgot to add that I tested the tubes and they all work on my tester
::::hello I moved and dropped my radio. Its a wards airline. Tubes are 25z5, 43, 6d6, 6d6, 6c6. My guess is the resistor on the back that is long, flat, and rectangular has opened up. What should I replace this with? Can I just substitute a resistor of approximate wattage and ohmage to drop 45 or so volts
:Hi Sean
: I assume, without looking at the schematic for this radio, that since the filaments are all in series that this resistor is also in series with the filament string, which would mean it is being used as a ballast resisitor, as long as you use a Wire Wound Resistor of the same value and wattage you will be ok.
:Mark
:

::Yes the filaments are in series so finguring out what the resistance and wattage is the issue. dont think I can measure the resistor since its open. If I go for a 46 volt drop then resistance would be 155 ohms at 14 watts........dont even know if I have anything close, .....might have to put several resistors in series to get that value and not burn them up
:
:::Hello I must also add that there is no isolation transformer in this set, and tubes heaters or filaments are in series
::::I forgot to add that I tested the tubes and they all work on my tester
:::::hello I moved and dropped my radio. Its a wards airline. Tubes are 25z5, 43, 6d6, 6d6, 6c6. My guess is the resistor on the back that is long, flat, and rectangular has opened up. What should I replace this with? Can I just substitute a resistor of approximate wattage and ohmage to drop 45 or so volts
::Hi Sean
:: I assume, without looking at the schematic for this radio, that since the filaments are all in series that this resistor is also in series with the filament string, which would mean it is being used as a ballast resisitor, as long as you use a Wire Wound Resistor of the same value and wattage you will be ok.
::Mark
::Hi Sean
What Model number is the radio, do you have a schematic for it?

:::Yes the filaments are in series so finguring out what the resistance and wattage is the issue. dont think I can measure the resistor since its open. If I go for a 46 volt drop then resistance would be 155 ohms at 14 watts........dont even know if I have anything close, .....might have to put several resistors in series to get that value and not burn them up
::
::::Hello I must also add that there is no isolation transformer in this set, and tubes heaters or filaments are in series
:::::I forgot to add that I tested the tubes and they all work on my tester
::::::hello I moved and dropped my radio. Its a wards airline. Tubes are 25z5, 43, 6d6, 6d6, 6c6. My guess is the resistor on the back that is long, flat, and rectangular has opened up. What should I replace this with? Can I just substitute a resistor of approximate wattage and ohmage to drop 45 or so volts
:::Hi Sean
::: I assume, without looking at the schematic for this radio, that since the filaments are all in series that this resistor is also in series with the filament string, which would mean it is being used as a ballast resisitor, as long as you use a Wire Wound Resistor of the same value and wattage you will be ok.
:::Mark
:::Hi Sean
: What Model number is the radio, do you have a schematic for it?

::::Yes the filaments are in series so finguring out what the resistance and wattage is the issue. dont think I can measure the resistor since its open. If I go for a 46 volt drop then resistance would be 155 ohms at 14 watts........dont even know if I have anything close, .....might have to put several resistors in series to get that value and not burn them up
:::
:::::Hello I must also add that there is no isolation transformer in this set, and tubes heaters or filaments are in series
::::::I forgot to add that I tested the tubes and they all work on my tester
:::::::hello I moved and dropped my radio. Its a wards airline. Tubes are 25z5, 43, 6d6, 6d6, 6c6. My guess is the resistor on the back that is long, flat, and rectangular has opened up. What should I replace this with? Can I just substitute a resistor of approximate wattage and ohmage to drop 45 or so volts
::::Hi Sean
:::: I assume, without looking at the schematic for this radio, that since the filaments are all in series that this resistor is also in series with the filament string, which would mean it is being used as a ballast resisitor, as long as you use a Wire Wound Resistor of the same value and wattage you will be ok.
::::Mark
::::Hi Sean
:: What Model number is the radio, do you have a schematic for it?
One other thing to take into consideration too is the filaments themselves are going to drop voltage, so if you set the resistance value for a 46 volt drop, your going too even further drop voltage with the filament string.
Mark

:well I added up the voltages of the filaments s5z5(25v) 43(25v), 2(6d6)(2x6.3v) 6c6(6.3v).......that comes up to 68.9volts........so `115vac subtract 68.9v is about 46 volts across the ballast resistor
:::::Yes the filaments are in series so finguring out what the resistance and wattage is the issue. dont think I can measure the resistor since its open. If I go for a 46 volt drop then resistance would be 155 ohms at 14 watts........dont even know if I have anything close, .....might have to put several resistors in series to get that value and not burn them up
::::
::::::Hello I must also add that there is no isolation transformer in this set, and tubes heaters or filaments are in series
:::::::I forgot to add that I tested the tubes and they all work on my tester
::::::::hello I moved and dropped my radio. Its a wards airline. Tubes are 25z5, 43, 6d6, 6d6, 6c6. My guess is the resistor on the back that is long, flat, and rectangular has opened up. What should I replace this with? Can I just substitute a resistor of approximate wattage and ohmage to drop 45 or so volts
:::::Hi Sean
::::: I assume, without looking at the schematic for this radio, that since the filaments are all in series that this resistor is also in series with the filament string, which would mean it is being used as a ballast resisitor, as long as you use a Wire Wound Resistor of the same value and wattage you will be ok.
:::::Mark
:::::Hi Sean
::: What Model number is the radio, do you have a schematic for it?
:One other thing to take into consideration too is the filaments themselves are going to drop voltage, so if you set the resistance value for a 46 volt drop, your going too even further drop voltage with the filament string.
:Mark

Hi Sean, you should look under resources and tips on this site. There is a good articule on replacing that dropping resistor with a capacitor. No more heat problems.
Greg

:hello I moved and dropped my radio. Its a wards airline. Tubes are 25z5, 43, 6d6, 6d6, 6c6. My guess is the resistor on the back that is long, flat, and rectangular has opened up. What should I replace this with? Can I just substitute a resistor of approximate wattage and ohmage to drop 45 or so volts

:hello can you point me to the exact location on this site to do that resistor and capacitor thing......I cant seem to find it
:Hi Sean, you should look under resources and tips on this site. There is a good articule on replacing that dropping resistor with a capacitor. No more heat problems.
:Greg
:
:
::hello I moved and dropped my radio. Its a wards airline. Tubes are 25z5, 43, 6d6, 6d6, 6c6. My guess is the resistor on the back that is long, flat, and rectangular has opened up. What should I replace this with? Can I just substitute a resistor of approximate wattage and ohmage to drop 45 or so volts

From any page look at the top and clic on references then tips & training and its the articule about the resistance line cords which is basically the same thing
Greg

::hello can you point me to the exact location on this site to do that resistor and capacitor thing......I cant seem to find it
::Hi Sean, you should look under resources and tips on this site. There is a good articule on replacing that dropping resistor with a capacitor. No more heat problems.
::Greg
::
::
:::hello I moved and dropped my radio. Its a wards airline. Tubes are 25z5, 43, 6d6, 6d6, 6c6. My guess is the resistor on the back that is long, flat, and rectangular has opened up. What should I replace this with? Can I just substitute a resistor of approximate wattage and ohmage to drop 45 or so volts

I've implemented the capacitor drop idea successfully - and I prefer it over a dropping resistor. No heat is generated.

Since you would be running AC through the cap, you'd need a nonpolarized cap. I've used Solen film caps. These are often sold for use in hi-fi speaker cross-overs. Be sure to get one with adequate voltage rating.

The Solens are rather large, so you may have to mount it on top of the chassis - with suitable insulation sleaving on the leads.

I've heard it said that you can use two electrolytics back to back, in series, with opposite polarity (each should be twice the total required capacity). I avoid this idea because I don't understand the physics involved that allows an electrolytic to be hooked up with reverse polarity for even half of a 60-Hz cycle. How does Cap 1 "know" that Cap 2 is in the circuit?

:WELL this radio is very limited in size and space, its a table top radio. There is one spot a cap could fit, right above the speaker.......but would like to know what value to use so I can just go and ask for one at a local motor shop...25z5 6d6 6d6 43 6c6
:I've implemented the capacitor drop idea successfully - and I prefer it over a dropping resistor. No heat is generated.
:
:Since you would be running AC through the cap, you'd need a nonpolarized cap. I've used Solen film caps. These are often sold for use in hi-fi speaker cross-overs. Be sure to get one with adequate voltage rating.
:
:The Solens are rather large, so you may have to mount it on top of the chassis - with suitable insulation sleaving on the leads.
:
:I've heard it said that you can use two electrolytics back to back, in series, with opposite polarity (each should be twice the total required capacity). I avoid this idea because I don't understand the physics involved that allows an electrolytic to be hooked up with reverse polarity for even half of a 60-Hz cycle. How does Cap 1 "know" that Cap 2 is in the circuit?

Sean, calculate the size of dropping cap based on Greg's references to articles on this forum. It's going to be in the neighborhood of 7uF.

I wouldn't suggest a motor run cap - too big, physically. Look for a Solen; you can Google for sources.

If this all seems too complicated, then use a dropping resistor.

Trying to find a small sized 7uf @400vdc non-electrolytic capacitor may not be as easy as this tip:
Just use a 1n4004 or 1n4007 rectifier diode in series to replace that resister. It will give you 1/2 wave pulsating DC for the filaments. It should work just fine with this easy fix.
I just did the same thing to replace a ballast tube and ended up with about 58-60v (on my true rms multimeter.) But I needed to get about 80V so I just also added a 15uf 160vdc cap from that point to ground... that kicked it up to just around 80Vdc. perfect.. easy fast ...no heat.
REF:
( http://antiqueradios.com/chrs/journal/ballast.html )

I encourage you to give either the condensers or the diodes a try. However, if you do not feel bold enough to try them, Radio Shack sells 100 and 50 ohm 10 watt wire wound resistors. This will give you your 150 ohms. However, they may get incredibly hot due to the .3 ampere tubes. I built an amplifier once that used 50L6, 35Z5, and 12SQ7 tubes. It, too, called for a 150 ohm resistor to take up the remaining current, which, in a 5 tube radio with .15 ampere tubes like those above, would be 24 volts. The resistor got very warm. Give it a try, though, if you have no luck with anything else. Using condensers sounds like a better idea, though--no heat.

Thomas

Another strange thing you could do, which may or may not take up the space a resistor or condenser would take, is to mount two 7 pin miniature tube sockets under the chassis. Wire pins 3 and 4 of each in series with eachother and the rest of the filament string. Insert two inexpensive 25C5 tubes. You now have a ballast resistor. If space is limited, though, the heat generated may damage components and wires (especially rubber wires).

Thomas

Peter, the diode will help. A diode will cut the power input by half. But (and it may take a little time to realize it), the RMS voltage to the set is dropped to only 1/sqrt2 = 70%. So, a diode will drop 120V to only about 84V (RMS). For most curtain burner sets, this isn't enough drop.

Regarding "true RMS" voltmeters: My expensive Fluke 179 is labeled "true RMS," but it gives the true RMS only if the voltage waveform is symmetric about the zero axis - which half of an AC waveform is not. For such a half-wave signal, the meter will show significantly lower voltage than the true RMS. At first, I though my Fluke was defective, until I was set straight by an engineer at Fluke.

Yes Doug you are correct. My perticular filament string and the lamps required just about 80v of the total 120vac. The ballast tube did that well albeit very hot.
When I replaced it with the diode my true-RMS Extech multimeter read ~54v on the DC scale and ~64v on the AC scale. I knew that for 1/2 wave it should be .707 x rms = ~84v effectively. I assumed my meter wasn't accurately reflecting that for reasons such as you've just explained. But I plodded onward to today's empirically achieved knowledge.
I was cautioned by the article on this that I must be aware that there is 84v effective juice there. But I was reading only 64v in the highest case. Now I knew there was something going on.... but I reasoned that WHATEVER the effective voltage was with the FULL sine wave AC...(1.41 x rms =169vac) it was NOW, (with 1/2 wave rectification) effectively HALF of that!
Call it 84v or whatever!
So I assessed my results based on how the radio seemed to play (listening to relative volume based on heaters working sufficiently equally as before) and the brightness of the lamps.
It all seemed a bit dim and lower in volume... so while measuring (inaccurately and not caring)the 1/2 wave on my DC scale I judged that THAT 54 volts as a relative point. I felt I needed a little more umph so I figured I could acheive it with a filter cap and sure enough when I added a 15uf@160vdc electrlytic... the voltage punched right up to just about 80v on my DC scale and the volume seemd about the same now as it was with the ballast tube. So I patted myself on the back and let the radio play on and off over the next few days. Until late last night while I was admiring my handiwork I noticed a funny smell and noticed a bulging end on that 15 uf cap! It was hot as blisters too.
I removed it and tried a 200v rating even a 450vdc rating and all aeemed to eventually get warm. So I checked it on my scope and saw that the cap was bringing up the DC base line about 30-40 volts or so with the 1/2 wave ripple of 120v or so peaks riding on that dc baseline. There was the answer!
120v pilses plus 30-40v dc is 150-160 volts and the cap was only rated 160 volts. BIG No no!!!
I've tried shot-gunning with a few test resistors like 50 ohms or 100 ohms in the string to help the RC time constant smooth out that ripple... to no avail in the sense that I get too much heat in the resistor ( I had a 100 ohm 30 watt-er ready to cook eggs). I guess it'll take some good old engenieering math to get it right. So for now I've gone back to a diode only.
So... DIODE= good... diode+filter cap= BAD!...
Any ideas? ...uh..er.. short of me taking a short engineering class?...
Those of you who can do the calculations can perhaps determine that I may be fighting a loosing battle because the rc combinations may generate as much heat as the ballast tube did.
I open to your thoughts.

:Yes Doug you are correct. My perticular filament string and the lamps required just about 80v of the total 120vac. The ballast tube did that well albeit very hot.
:When I replaced it with the diode my true-RMS Extech multimeter read ~54v on the DC scale and ~64v on the AC scale. I knew that for 1/2 wave it should be .707 x rms = ~84v effectively. I assumed my meter wasn't accurately reflecting that for reasons such as you've just explained. But I plodded onward to today's empirically achieved knowledge.
:I was cautioned by the article on this that I must be aware that there is 84v effective juice there. But I was reading only 64v in the highest case. Now I knew there was something going on.... but I reasoned that WHATEVER the effective voltage was with the FULL sine wave AC...(1.41 x rms =169vac) it was NOW, (with 1/2 wave rectification) effectively HALF of that!
:Call it 84v or whatever!
:So I assessed my results based on how the radio seemed to play (listening to relative volume based on heaters working sufficiently equally as before) and the brightness of the lamps.
:It all seemed a bit dim and lower in volume... so while measuring (inaccurately and not caring)the 1/2 wave on my DC scale I judged that THAT 54 volts as a relative point. I felt I needed a little more umph so I figured I could acheive it with a filter cap and sure enough when I added a 15uf@160vdc electrlytic... the voltage punched right up to just about 80v on my DC scale and the volume seemd about the same now as it was with the ballast tube. So I patted myself on the back and let the radio play on and off over the next few days. Until late last night while I was admiring my handiwork I noticed a funny smell and noticed a bulging end on that 15 uf cap! It was hot as blisters too.
:I removed it and tried a 200v rating even a 450vdc rating and all aeemed to eventually get warm. So I checked it on my scope and saw that the cap was bringing up the DC base line about 30-40 volts or so with the 1/2 wave ripple of 120v or so peaks riding on that dc baseline. There was the answer!
: 120v pilses plus 30-40v dc is 150-160 volts and the cap was only rated 160 volts. BIG No no!!!
:I've tried shot-gunning with a few test resistors like 50 ohms or 100 ohms in the string to help the RC time constant smooth out that ripple... to no avail in the sense that I get too much heat in the resistor ( I had a 100 ohm 30 watt-er ready to cook eggs). I guess it'll take some good old engenieering math to get it right. So for now I've gone back to a diode only.
:So... DIODE= good... diode+filter cap= BAD!...
:Any ideas? ...uh..er.. short of me taking a short engineering class?...
:Those of you who can do the calculations can perhaps determine that I may be fighting a loosing battle because the rc combinations may generate as much heat as the ballast tube did.
:I'm open to your thoughts.

In reference to the article suggesting the use of a capacitor:
http://www.antiquewireless.org/otb/resto801.htm

I also did a few experiments with that and here's what I found. I wrote this to the author just a few moments ago as I am hoping that he can help clarify things.
Here it is:
--------
Hi Ken:
I've been reading your article below.

http://www.antiquewireless.org/otb/resto801.htm

you state :
---------------------
"Finding a capacitor of the proper value may be difficult. Don't use electrolytics, even back-to-back. They get hot when carrying AC current. Use Mylar or polypropylene units. As a rule of thumb, the AC rating of a film capacitor is 40% of its DC voltage rating. A 400V DC capacitor can easily withstand 160V AC. If you can't find a combination of capacitors to give the required value, you can put a resistor in series with a larger value. "
------------------
Is that last line correct?
How would a resistor in series with a larger value help bring the value down?
Did you possibly mean that you can put a resistor in parallel with a larger cap to bring the combined value down?

As an experiment I tried using a (1" wide by 1-1/2" long by 1/4" thick)...big old flat yellow plastic, maybe mylar? cap I found in my junk box that was rated as 200vdc and marked 4.8uf... but my nifty new digital capacitance meter read it as 6.1 uf
I tried it. It drops the 125vac down to 43vac. My scope shows it reducing the 350vac P-P down to as 150vac P-P
Does that calculate out properly? ... your example showing 6.7uf should drop the 120vac down to 19vac right?
So why is my 6.1uf cap only bringing it down to 43vac?

For the radio I'm using ...my filament string requires about 75vac
So..just as a test, I tried two 10uf 450Vdc electrolytic caps back to back in series = 5 uf... but that only brings it to 41vac
So I tried a 22uf and a 10uf back-back and came up with an effective value of 7.25uf and that produced an acceptable 61vac.
They didn't seem to be getting very warm if at all. Is it reasonable to use them if they are 450vdc?
My scope showed a 150vPP on the output.... but of course the input is seeing 350vPP or so.
But none of these results seem to match your figures, what am I missing?

Thanks for listening..
Peter

Not sure why you get less power into the heater string with a diode alone. My wild guess is that there is a cold solder joint or a short somewhere.

The reason you have a problem with your diode+RC approach is that the C is too large for your purpose.

To make it simple, let us assume that the capacitor is fully charged in the diode conducting half cycle, the energy stored is (CV^2)/2. This energy is mostly discharged in the other half cyle, since the energy remianed in the 40V DC capacitor is rather small compaired to the energy in 170V DC capacitor (about 5.5%). And because each cycle is 1/60 sec., the equivalent "RMS" power is 60*(CV^2)/2=(30V^2)C. For a peak of 170V, this comes out to 0.867C watts, where C is in uF.

As such, the addition of a 15uF capacitor is equivalent to dumping an extra 15*0.867=13 watts into the heater string. Assuming your heater current is 300mA, a 100 ohm resistor will absorb 9 watts. If you have a short after the resistor, it will consume even more power.

Nonehteless, to increase power to heater string with your halfwave heater supply, you can start with a smaller capacitor. For example, a 80V 300mA heater is 24W, for a 10% increase, you need C=2.4/0.867=2.8, so make it 3uF. A 5uF capacitor will give you 18% boost. And your 15uF capacitor is equivalent to more than 50% boost.

:Yes Doug you are correct. My perticular filament string and the lamps required just about 80v of the total 120vac. The ballast tube did that well albeit very hot.
:When I replaced it with the diode my true-RMS Extech multimeter read ~54v on the DC scale and ~64v on the AC scale. I knew that for 1/2 wave it should be .707 x rms = ~84v effectively. I assumed my meter wasn't accurately reflecting that for reasons such as you've just explained. But I plodded onward to today's empirically achieved knowledge.
:I was cautioned by the article on this that I must be aware that there is 84v effective juice there. But I was reading only 64v in the highest case. Now I knew there was something going on.... but I reasoned that WHATEVER the effective voltage was with the FULL sine wave AC...(1.41 x rms =169vac) it was NOW, (with 1/2 wave rectification) effectively HALF of that!
:Call it 84v or whatever!
:So I assessed my results based on how the radio seemed to play (listening to relative volume based on heaters working sufficiently equally as before) and the brightness of the lamps.
:It all seemed a bit dim and lower in volume... so while measuring (inaccurately and not caring)the 1/2 wave on my DC scale I judged that THAT 54 volts as a relative point. I felt I needed a little more umph so I figured I could acheive it with a filter cap and sure enough when I added a 15uf@160vdc electrlytic... the voltage punched right up to just about 80v on my DC scale and the volume seemd about the same now as it was with the ballast tube. So I patted myself on the back and let the radio play on and off over the next few days. Until late last night while I was admiring my handiwork I noticed a funny smell and noticed a bulging end on that 15 uf cap! It was hot as blisters too.
:I removed it and tried a 200v rating even a 450vdc rating and all aeemed to eventually get warm. So I checked it on my scope and saw that the cap was bringing up the DC base line about 30-40 volts or so with the 1/2 wave ripple of 120v or so peaks riding on that dc baseline. There was the answer!
: 120v pilses plus 30-40v dc is 150-160 volts and the cap was only rated 160 volts. BIG No no!!!
:I've tried shot-gunning with a few test resistors like 50 ohms or 100 ohms in the string to help the RC time constant smooth out that ripple... to no avail in the sense that I get too much heat in the resistor ( I had a 100 ohm 30 watt-er ready to cook eggs). I guess it'll take some good old engenieering math to get it right. So for now I've gone back to a diode only.
:So... DIODE= good... diode+filter cap= BAD!...
:Any ideas? ...uh..er.. short of me taking a short engineering class?...
:Those of you who can do the calculations can perhaps determine that I may be fighting a loosing battle because the rc combinations may generate as much heat as the ballast tube did.
:I open to your thoughts.

I'm not sure I follow you on a few things.
I'm geting less power into the heater string with the 1/2 wave diode vs the ballast tube because i'm only giving 1/2 the available AC... I think its .707 x rms=84v peak as opposed to 1.41 x rms = 169v peak

It is drawing .3amps which is correct so I don't think there's a short.
I was tring to figure out out to achieve about 80v DC to run the heaters. But initally with just a diode I'll be getting 84v peaks of pulsating dc... right?

I wanted to smooth that high ripple out to something approaching 80v dc but just adding a capacitor to ground right after the rectifier as it enters the heater string. I was hoping not to need to build a full 'pi' filter with a resistor inbetween the 2 caps that would be dropping more voltage and generating heat again. So I used that 15uf cap. After wich the general brighteness of the lamps and volume sounded a bit better than with the diode alone.
The cap just got too hot. Looking at the waveform I saw of about 120v Peak ripple with only steep slight slopes during the non-pass 1/2cycle. The ripple was riding on an elevated base of about 30vdc as shown on my scope in DC.
I don't care if it's all ripple or pure dc as far heating the filaments but I wanted to provide the appropriate required 80 volts or thereabouts that the filaments added up to including the 6.3v lamps. That's all.
Along the way the 15uf cap starts overheating so I see that it seems to be the 120v peaks riding on that 30v dc base line.... no?
If I understand you correctly do you believe that if I just add a 3uf cap rated @160vdc to ground right after the diode (no pi filter arrangement just the filament load) that the 1/2 cycle 120 volt ripple peaks will smooth out?... and I'll be dealing with a more digestable DC for that 3uf electrolytic to swallow?

:Not sure why you get less power into the heater string with a diode alone. My wild guess is that there is a cold solder joint or a short somewhere.
:
:The reason you have a problem with your diode+RC approach is that the C is too large for your purpose.
:
:To make it simple, let us assume that the capacitor is fully charged in the diode conducting half cycle, the energy stored is (CV^2)/2. This energy is mostly discharged in the other half cyle, since the energy remianed in the 40V DC capacitor is rather small compaired to the energy in 170V DC capacitor (about 5.5%). And because each cycle is 1/60 sec., the equivalent "RMS" power is 60*(CV^2)/2=(30V^2)C. For a peak of 170V, this comes out to 0.867C watts, where C is in uF.
:
:As such, the addition of a 15uF capacitor is equivalent to dumping an extra 15*0.867=13 watts into the heater string. Assuming your heater current is 300mA, a 100 ohm resistor will absorb 9 watts. If you have a short after the resistor, it will consume even more power.
:
:Nonehteless, to increase power to heater string with your halfwave heater supply, you can start with a smaller capacitor. For example, a 80V 300mA heater is 24W, for a 10% increase, you need C=2.4/0.867=2.8, so make it 3uF. A 5uF capacitor will give you 18% boost. And your 15uF capacitor is equivalent to more than 50% boost.
:
:
::Yes Doug you are correct. My perticular filament string and the lamps required just about 80v of the total 120vac. The ballast tube did that well albeit very hot.
::When I replaced it with the diode my true-RMS Extech multimeter read ~54v on the DC scale and ~64v on the AC scale. I knew that for 1/2 wave it should be .707 x rms = ~84v effectively. I assumed my meter wasn't accurately reflecting that for reasons such as you've just explained. But I plodded onward to today's empirically achieved knowledge.
::I was cautioned by the article on this that I must be aware that there is 84v effective juice there. But I was reading only 64v in the highest case. Now I knew there was something going on.... but I reasoned that WHATEVER the effective voltage was with the FULL sine wave AC...(1.41 x rms =169vac) it was NOW, (with 1/2 wave rectification) effectively HALF of that!
::Call it 84v or whatever!
::So I assessed my results based on how the radio seemed to play (listening to relative volume based on heaters working sufficiently equally as before) and the brightness of the lamps.
::It all seemed a bit dim and lower in volume... so while measuring (inaccurately and not caring)the 1/2 wave on my DC scale I judged that THAT 54 volts as a relative point. I felt I needed a little more umph so I figured I could acheive it with a filter cap and sure enough when I added a 15uf@160vdc electrlytic... the voltage punched right up to just about 80v on my DC scale and the volume seemd about the same now as it was with the ballast tube. So I patted myself on the back and let the radio play on and off over the next few days. Until late last night while I was admiring my handiwork I noticed a funny smell and noticed a bulging end on that 15 uf cap! It was hot as blisters too.
::I removed it and tried a 200v rating even a 450vdc rating and all aeemed to eventually get warm. So I checked it on my scope and saw that the cap was bringing up the DC base line about 30-40 volts or so with the 1/2 wave ripple of 120v or so peaks riding on that dc baseline. There was the answer!
:: 120v pilses plus 30-40v dc is 150-160 volts and the cap was only rated 160 volts. BIG No no!!!
::I've tried shot-gunning with a few test resistors like 50 ohms or 100 ohms in the string to help the RC time constant smooth out that ripple... to no avail in the sense that I get too much heat in the resistor ( I had a 100 ohm 30 watt-er ready to cook eggs). I guess it'll take some good old engenieering math to get it right. So for now I've gone back to a diode only.
::So... DIODE= good... diode+filter cap= BAD!...
::Any ideas? ...uh..er.. short of me taking a short engineering class?...
::Those of you who can do the calculations can perhaps determine that I may be fighting a loosing battle because the rc combinations may generate as much heat as the ballast tube did.
::I open to your thoughts.

Peter, I think we're making this too complicated.

First, if you want an effective rms voltage of about 84V to the heater string, all you need is the diode in series with the 120V. You're done. Don't try to measure the voltage, because the meter won't work with an asymmetrical waveform. Don't worry about peak-to-peak, etc. You're done.

Now, if you slap a line-to-line filter capacitor on the output of the diode, you've now got a DC power supply which will put out 120 x 1.414 = 170V, less ripple. This is not the way to go.

If 84V rms is not what you want, then either use a ballast resistor, a dropping cap, or a transformer. A pi filter isn't the way to go.

:I'm not sure I follow you on a few things.

That is Ok. Let's try it again.

:I'm geting less power into the heater string with the 1/2 wave diode vs the ballast tube because i'm only giving 1/2 the available AC... I think its .707 x rms=84v peak as opposed to 1.41 x rms = 169v peak

As Doug pointed out earlier, 84V is the RMS for a 1/2 wave rectifier. In this case, your load is getting only half cycle of the 120V ac, and not getting anything at the other half cycle, so in the conduction half cycle, the wave form is exactly the same as the 120V ac, i.e. the peak is still 169V with 1/2 wave rectifier. After all, the wave form is supposed to be the upper half of the 120V ac sine wave.

Since you mentioned 80V heater string, I was assuming that the ballast was providing 80V quivalent to the heater string, so I thought 84V rms would be sufficient. Maybe the original design was little bit hotter than it should be? Or more likely, maybe the voltage dependent heater resistance plays a role here. If the heater thermal time constant is too short, heater temperature doesn't stay relatively constant, and the resistance rises with higher temperature. So in the conduction half cycle, when the heater gets hotter, heater resistance gets higher (vs. a constant resistor load for power supply), it effectively consumes less power in a 1/2 wave rectifier supply than in a 80V full wave or DC situation?

:It is drawing .3amps which is correct so I don't think there's a short.
:I was tring to figure out out to achieve about 80v DC to run the heaters. But initally with just a diode I'll be getting 84v peaks of pulsating dc... right?

As mentioned above, with just a diode, you get 84V rms to the heater, not peaks. The peaks are still 169V.

:I wanted to smooth that high ripple out to something approaching 80v dc but just adding a capacitor to ground right after the rectifier as it enters the heater string. I was hoping not to need to build a full 'pi' filter with a resistor inbetween the 2 caps that would be dropping more voltage and generating heat again. So I used that 15uf cap. After wich the general brighteness of the lamps and volume sounded a bit better than with the diode alone.

As I mentioned earlier, you can use a cap to boost power into heater string, so no problem here.

:The cap just got too hot. Looking at the waveform I saw of about 120v Peak ripple with only steep slight slopes during the non-pass 1/2cycle. The ripple was riding on an elevated base of about 30vdc as shown on my scope in DC.
:I don't care if it's all ripple or pure dc as far heating the filaments but I wanted to provide the appropriate required 80 volts or thereabouts that the filaments added up to including the 6.3v lamps. That's all.
:Along the way the 15uf cap starts overheating so I see that it seems to be the 120v peaks riding on that 30v dc base line.... no?

Your observation of the wave form seems to indicate that things are working correctly. The reason for the cap to get too hot is probably that it's voltage rating is not sufficient for this application. Since the peak is still 169V, you need a 200V or higher rating cap, hopefully the ones designed for high ripple applications.

:If I understand you correctly do you believe that if I just add a 3uf cap rated @160vdc to ground right after the diode (no pi filter arrangement just the filament load) that the 1/2 cycle 120 volt ripple peaks will smooth out?... and I'll be dealing with a more digestable DC for that 3uf electrolytic to swallow?

The resistor slows capacitor discharge in the non-conducting half cycle, but it also reduce power to the heater string during the conduction half cycle. So your 15uF + 100 ohm combination is delivering roughly the same power to the heater string as the diode alone, assuming the heater resistance stays the same for both scenarios. The fact that the heater string runs cooler with 1/2 wave rectifier seems to indicate that the non-linear voltage dependent heater resistance mechanism mentioned above is the culprit.

Yes, you can use only a capacitor. What you need now is higher voltage rating caps, 200V or better yet 250V ones. As my previous prediction was based on a constant resistor load, if the non-liner heater resistance mechanism is the true cause of your problem, it might not apply. What you need to do is to try different values until you are happy with it, be it 5, 10, or 15 uF.

Okay folks. Let's simplify things. I read a lot and then I got tired of reading. The only voltage you have available is 120 volts. There's nothing more and nothing less. There is the unloaded peak when the rectified voltage is filtered. A 200 volt condenser should suffice for this. If it is getting hot, then you are either connecting it backwards or incorrectly. There is no way that this peak exists when the rectified voltage is loaded down by tube filaments.

Check the polarity across the heater string. Place the electrolytic across the HEATER string observing correct polarity. This will effectively filter the voltage going to the heaters, removing some of the ripple and thereby increasing the apparent voltage. If you want brighter heaters, increase the electrolytic value. If you want dimmer heaters, decrease the value. Increasing the value puts in an electrolytic which holds more of a charge, and can fill in more of the gap between each half wave. Decreasing fills in the gaps less. There is absolutely no reason for the electrolytic to get hot if it's wired correctly. With the heaters loading down that diode there's no way that there are any peak voltages climbing above 200 volts. You shouldn't be placing the electrolytic in any other way than across the heater string. The diode should feed both the heater string and the electrolytic, which are in parallel with eachother. Think of a conventional radio B supply and you'll get it all correct.

Peter, I'm getting the idea that you're adding the voltage to the heaters and the line voltage...not sure why....but it seems so. The voltage to the heaters is what is available after the diode has apparently dropped the line voltage down to this value. Of course it isn't really dropping anything, but rather cutting the time which the 120 volts is available to the filaments. Either way, the 30 to 40 volts available to the heaters cannot be added to the line voltage. All that is available, as stated before, is a total of 120 volts. Use a 200 WVDC electrolytic.

Thomas

First, don't try to measure the voltage across the heater string (after the diode). Even if you have a true RMS meter, it will give you a low number because the meter will assume that the waveform is symmetrical, which it is not.

A diode by itself, without any capacitor, with reduce the effective RMS AC voltage to 70%: 120V x 70% = 84V. That's the RMS voltage that will appear across the heater string, even though your meter will say it's less.

Sean, you said that the heater string wants to see 69V. Well, the diode by itself and no cap, will put out 120V x 70% = 84V - WHICH IS MORE THAN THE VOLTAGE YOU DESIRE (69V). So I cannot understand why you think you need to boost the voltage - it's already too high!

Let's not gum this anymore until Sean works thru the reasoning here - we're just going around in circles. And, Sean, don't use your meter - it's worthless for what your trying to measure.

Hello I did put 2 10 uf caps back to back and I get close to the voltage at tube heater elements. My voltage here is high anyway(measuring with a digital radioshack meter) So as to the correct voltage to shoot for um yea well I would think if each tube is recieving its rated heater voltage then I am good.
So now it only humms. Touch either grid cap of the 6d6 tubes and it humms louder. Touch the grid cap of the 6c6 momentarily and it goes into a hiss with a slight squeal....so my guess is I am makeing it go into oscillations that arent supposed to happen which leads me to believe that something is messed up in the tuning section? I am thinking this is not good since it worked before I dropped it............I damaged a coil somewhere???I dont have a schematic for it ...........still searching
:First, don't try to measure the voltage across the heater string (after the diode). Even if you have a true RMS meter, it will give you a low number because the meter will assume that the waveform is symmetrical, which it is not.
:
:A diode by itself, without any capacitor, with reduce the effective RMS AC voltage to 70%: 120V x 70% = 84V. That's the RMS voltage that will appear across the heater string, even though your meter will say it's less.
:
:Sean, you said that the heater string wants to see 69V. Well, the diode by itself and no cap, will put out 120V x 70% = 84V - WHICH IS MORE THAN THE VOLTAGE YOU DESIRE (69V). So I cannot understand why you think you need to boost the voltage - it's already too high!
:
:Let's not gum this anymore until Sean works thru the reasoning here - we're just going around in circles. And, Sean, don't use your meter - it's worthless for what your trying to measure.

Does it hum like power supply hum or does it hum like poor shielding in the audio? Is the volume control on the 1st audio tube or is it on the antenna circuit? Can you turn down the hum with the volume control? Check your wiring under the chassis. Check for shorts and broken wires. Test your tubes. See to it that none have element to element shorts.

What is the model number of your set? It'd be nice to see a schematic so that I could see how the filaments are wired and if your modification affected anything in the power supply.

You shouldn't have to use electrolytics back to back if your diode is working properly. Did you use a regular diode or a zener diode? A zener diode will allow current to pass in both directions. Your diode must have absolutely no leakage in the reverse direction. Your meter should read infinity. Anything less is unacceptable. Then all you need to do is observe polarity across the tube filaments and then install the electrolytic in this direction. Use a 200 WV electrolytic.

Thomas

:Hello I found it its 62-104...well it does the usual radio hum, only just a little bit louder. Actually it hums like a cap is missing but not too loud. If you touch the 6c6 grid cap it will go into oscillations and stay there..mostly a hiss with just a little bit of squeal..........varying the tuning condender changes it a little bit.
:Does it hum like power supply hum or does it hum like poor shielding in the audio? Is the volume control on the 1st audio tube or is it on the antenna circuit? Can you turn down the hum with the volume control? Check your wiring under the chassis. Check for shorts and broken wires. Test your tubes. See to it that none have element to element shorts.
:
:What is the model number of your set? It'd be nice to see a schematic so that I could see how the filaments are wired and if your modification affected anything in the power supply.
:
:You shouldn't have to use electrolytics back to back if your diode is working properly. Did you use a regular diode or a zener diode? A zener diode will allow current to pass in both directions. Your diode must have absolutely no leakage in the reverse direction. Your meter should read infinity. Anything less is unacceptable. Then all you need to do is observe polarity across the tube filaments and then install the electrolytic in this direction. Use a 200 WV electrolytic.
:
:Thomas

Well be sure that when you put in the diode/condenser arrangement that you didn't modify any other wiring. The filaments and ballast in this radio should not have any affect on the B supply, as shown in the schematic.

The next thing you should do is test tubes for element to element shorts (between each grid, from the outermost grid to the plate, and from the innermost grid to the cathode, between the cathode and the heater, etc.).

Then after that you should check your components and your wiring. Check each condenser for shorts, leakage, open connections, etc. Remove each condenser when you test it. You should probably check voltages within your set, too. I usually test these after I test components, as it's wiser to first find obviously bad components, than it is to leave the set running with possibly bad components which may be causing harm.

Thomas

:Hello, I found a wire that goes from the tuning condenser to the trimmer or padder condenser broke loose, now the radio plays almost normal, but there is a oscillating hiss/ like wind whistling around a house, its not loud at all and only gets louder proportional to volume........its almost like in the philco radios when you mess with the adjustment caps and it makes the soft hiss/whistling sound. This radio only has three adjustment caps that I know of. Two are on the tuning condenser and one is mounted to the chassis and the body of it is porcelin
:Well be sure that when you put in the diode/condenser arrangement that you didn't modify any other wiring. The filaments and ballast in this radio should not have any affect on the B supply, as shown in the schematic.
:
:The next thing you should do is test tubes for element to element shorts (between each grid, from the outermost grid to the plate, and from the innermost grid to the cathode, between the cathode and the heater, etc.).
:
:Then after that you should check your components and your wiring. Check each condenser for shorts, leakage, open connections, etc. Remove each condenser when you test it. You should probably check voltages within your set, too. I usually test these after I test components, as it's wiser to first find obviously bad components, than it is to leave the set running with possibly bad components which may be causing harm.
:
:Thomas

:Hello, I also noticed that you can only hear the wind sound when you tune in a station, so does that mean its in the front end of the radio?
::Hello, I found a wire that goes from the tuning condenser to the trimmer or padder condenser broke loose, now the radio plays almost normal, but there is a oscillating hiss/ like wind whistling around a house, its not loud at all and only gets louder proportional to volume........its almost like in the philco radios when you mess with the adjustment caps and it makes the soft hiss/whistling sound. This radio only has three adjustment caps that I know of. Two are on the tuning condenser and one is mounted to the chassis and the body of it is porcelin
::Well be sure that when you put in the diode/condenser arrangement that you didn't modify any other wiring. The filaments and ballast in this radio should not have any affect on the B supply, as shown in the schematic.
::
::The next thing you should do is test tubes for element to element shorts (between each grid, from the outermost grid to the plate, and from the innermost grid to the cathode, between the cathode and the heater, etc.).
::
::Then after that you should check your components and your wiring. Check each condenser for shorts, leakage, open connections, etc. Remove each condenser when you test it. You should probably check voltages within your set, too. I usually test these after I test components, as it's wiser to first find obviously bad components, than it is to leave the set running with possibly bad components which may be causing harm.
::
::Thomas

Well, first, the broken wire to the tuning condenser could be part of the hum, though as you describe it, it's probably not. Did the hum go away?

Regarding hiss, you could have a broken wire to one of the filter condensers in the RF section, like C3. This condenser filteres the B+ to the RF tubes. If it is non-functional, unwanted oscillation can occur between the tubes through this circuit. Check all condensers for proper operation. Also check the tubes. The volume control controls the gain of the 6D6 tube. This tube and the oscillator tube are what you should look at because they are what gets cut out with the volume control. Be sure that you don't have a computer or a television on in your home. This can cause hiss interference, which usually increases when you tune in a station.

Check R1 and C2, which may cause odd operation if they fail (sorry to sound so vague, but there are many things that can happen when they fail, though oscillation isn't usually one of them). C15 could allow oscillation if it was open or disconnected. Variations in cathode voltage in the 6D6 can be fed back to the 6C6 antenna grid, which will be amplified by the 6C6 and then sent to the 6D6, where it will again affect cathode voltage. This will obviously be considered feedback or oscillation.

Thomas

:Hello, I tried different tubes and still the same effect. It sounds exactly like when you have the station off tune and you get a low growling sound like you are almost on station and you need to tune the knob in just a little better although I know you arent supposed to get this sound. so when I check this stuff I am not sure what exactly to check other than component values
:Well, first, the broken wire to the tuning condenser could be part of the hum, though as you describe it, it's probably not. Did the hum go away?
:
:Regarding hiss, you could have a broken wire to one of the filter condensers in the RF section, like C3. This condenser filteres the B+ to the RF tubes. If it is non-functional, unwanted oscillation can occur between the tubes through this circuit. Check all condensers for proper operation. Also check the tubes. The volume control controls the gain of the 6D6 tube. This tube and the oscillator tube are what you should look at because they are what gets cut out with the volume control. Be sure that you don't have a computer or a television on in your home. This can cause hiss interference, which usually increases when you tune in a station.
:
:Check R1 and C2, which may cause odd operation if they fail (sorry to sound so vague, but there are many things that can happen when they fail, though oscillation isn't usually one of them). C15 could allow oscillation if it was open or disconnected. Variations in cathode voltage in the 6D6 can be fed back to the 6C6 antenna grid, which will be amplified by the 6C6 and then sent to the 6D6, where it will again affect cathode voltage. This will obviously be considered feedback or oscillation.
:
:Thomas

:Hello, when checking with my multimeter, do I have to isolate the 35 mmf cap from the 1 meg resistor?
::Hello, I tried different tubes and still the same effect. It sounds exactly like when you have the station off tune and you get a low growling sound like you are almost on station and you need to tune the knob in just a little better although I know you arent supposed to get this sound. so when I check this stuff I am not sure what exactly to check other than component values
::Well, first, the broken wire to the tuning condenser could be part of the hum, though as you describe it, it's probably not. Did the hum go away?
::
::Regarding hiss, you could have a broken wire to one of the filter condensers in the RF section, like C3. This condenser filteres the B+ to the RF tubes. If it is non-functional, unwanted oscillation can occur between the tubes through this circuit. Check all condensers for proper operation. Also check the tubes. The volume control controls the gain of the 6D6 tube. This tube and the oscillator tube are what you should look at because they are what gets cut out with the volume control. Be sure that you don't have a computer or a television on in your home. This can cause hiss interference, which usually increases when you tune in a station.
::
::Check R1 and C2, which may cause odd operation if they fail (sorry to sound so vague, but there are many things that can happen when they fail, though oscillation isn't usually one of them). C15 could allow oscillation if it was open or disconnected. Variations in cathode voltage in the 6D6 can be fed back to the 6C6 antenna grid, which will be amplified by the 6C6 and then sent to the 6D6, where it will again affect cathode voltage. This will obviously be considered feedback or oscillation.
::
::Thomas

:Hello when checking r1 and r5 they measure 1.48 meg and 1.52 meg respectively....are these resistors taking a dump?
::Hello, when checking with my multimeter, do I have to isolate the 35 mmf cap from the 1 meg resistor?
:::Hello, I tried different tubes and still the same effect. It sounds exactly like when you have the station off tune and you get a low growling sound like you are almost on station and you need to tune the knob in just a little better although I know you arent supposed to get this sound. so when I check this stuff I am not sure what exactly to check other than component values
:::Well, first, the broken wire to the tuning condenser could be part of the hum, though as you describe it, it's probably not. Did the hum go away?
:::
:::Regarding hiss, you could have a broken wire to one of the filter condensers in the RF section, like C3. This condenser filteres the B+ to the RF tubes. If it is non-functional, unwanted oscillation can occur between the tubes through this circuit. Check all condensers for proper operation. Also check the tubes. The volume control controls the gain of the 6D6 tube. This tube and the oscillator tube are what you should look at because they are what gets cut out with the volume control. Be sure that you don't have a computer or a television on in your home. This can cause hiss interference, which usually increases when you tune in a station.
:::
:::Check R1 and C2, which may cause odd operation if they fail (sorry to sound so vague, but there are many things that can happen when they fail, though oscillation isn't usually one of them). C15 could allow oscillation if it was open or disconnected. Variations in cathode voltage in the 6D6 can be fed back to the 6C6 antenna grid, which will be amplified by the 6C6 and then sent to the 6D6, where it will again affect cathode voltage. This will obviously be considered feedback or oscillation.
:::
:::Thomas

Well its not a hiss anymore since I soldered the wire back on the porcelin trimmer cap..you do get stations but there is still is somewhat of a growl like a trimmer cap is out of adjustment but nothing will adjust it out. OK the station I am tuning in is the strongest and it is 1480..........I just tried a station midway in the dial.......and its fine or better at least........now I am clueless

:::Hello when checking r1 and r5 they measure 1.48 meg and 1.52 meg respectively....are these resistors taking a dump?
:::Hello, when checking with my multimeter, do I have to isolate the 35 mmf cap from the 1 meg resistor?
::::Hello, I tried different tubes and still the same effect. It sounds exactly like when you have the station off tune and you get a low growling sound like you are almost on station and you need to tune the knob in just a little better although I know you arent supposed to get this sound. so when I check this stuff I am not sure what exactly to check other than component values
::::Well, first, the broken wire to the tuning condenser could be part of the hum, though as you describe it, it's probably not. Did the hum go away?
::::
::::Regarding hiss, you could have a broken wire to one of the filter condensers in the RF section, like C3. This condenser filteres the B+ to the RF tubes. If it is non-functional, unwanted oscillation can occur between the tubes through this circuit. Check all condensers for proper operation. Also check the tubes. The volume control controls the gain of the 6D6 tube. This tube and the oscillator tube are what you should look at because they are what gets cut out with the volume control. Be sure that you don't have a computer or a television on in your home. This can cause hiss interference, which usually increases when you tune in a station.
::::
::::Check R1 and C2, which may cause odd operation if they fail (sorry to sound so vague, but there are many things that can happen when they fail, though oscillation isn't usually one of them). C15 could allow oscillation if it was open or disconnected. Variations in cathode voltage in the 6D6 can be fed back to the 6C6 antenna grid, which will be amplified by the 6C6 and then sent to the 6D6, where it will again affect cathode voltage. This will obviously be considered feedback or oscillation.
::::
::::Thomas

:Ok yep I am stumped, I did check the caps and they are.221 nanofarads or around there(the grid cap caps)dont see how a cap can increase in size. If a radio can tune in stations better on downward on the dial what is this?????
:Well its not a hiss anymore since I soldered the wire back on the porcelin trimmer cap..you do get stations but there is still is somewhat of a growl like a trimmer cap is out of adjustment but nothing will adjust it out. OK the station I am tuning in is the strongest and it is 1480..........I just tried a station midway in the dial.......and its fine or better at least........now I am clueless
:
::::Hello when checking r1 and r5 they measure 1.48 meg and 1.52 meg respectively....are these resistors taking a dump?
::::Hello, when checking with my multimeter, do I have to isolate the 35 mmf cap from the 1 meg resistor?
:::::Hello, I tried different tubes and still the same effect. It sounds exactly like when you have the station off tune and you get a low growling sound like you are almost on station and you need to tune the knob in just a little better although I know you arent supposed to get this sound. so when I check this stuff I am not sure what exactly to check other than component values
:::::Well, first, the broken wire to the tuning condenser could be part of the hum, though as you describe it, it's probably not. Did the hum go away?
:::::
:::::Regarding hiss, you could have a broken wire to one of the filter condensers in the RF section, like C3. This condenser filteres the B+ to the RF tubes. If it is non-functional, unwanted oscillation can occur between the tubes through this circuit. Check all condensers for proper operation. Also check the tubes. The volume control controls the gain of the 6D6 tube. This tube and the oscillator tube are what you should look at because they are what gets cut out with the volume control. Be sure that you don't have a computer or a television on in your home. This can cause hiss interference, which usually increases when you tune in a station.
:::::
:::::Check R1 and C2, which may cause odd operation if they fail (sorry to sound so vague, but there are many things that can happen when they fail, though oscillation isn't usually one of them). C15 could allow oscillation if it was open or disconnected. Variations in cathode voltage in the 6D6 can be fed back to the 6C6 antenna grid, which will be amplified by the 6C6 and then sent to the 6D6, where it will again affect cathode voltage. This will obviously be considered feedback or oscillation.
:::::
:::::Thomas

When you test any resistor or condenser, you should isolate it from the circuit. To do this, disconnect one or both leads. When making checks, do not touch the meter leads or you'll throw off the reading with the leakage in your hand. It isn't exactly necessary to test condenser capacitance, though it's a plus. Condensers don't usually change capacitance much. What you want to look for is leakage. Any leakage at all is unacceptable. DID YOU CHECK C15 and C9? These are critical (not in value, but in presence), and if they're open or disconnected, they'll allow oscillation.

Regarding those resistors, they have drifted somewhat high, but this drift is not significant in the circuits which they are used in. You may substitute new resistors if you wish. If R5 drifts too high, it'll change the way the detector detects (may cause distortion).

How well does the radio track? Do stations line up fairly well across the dial? No station should be more than about 30 KC off position. If they are off, especially at the low end, C10 may need a re-tune. I just don't see trimmers going out of tune from dropping the set. You'd have to turn the screws a few turns. Still, having sensitivity decrease towards the low end of the dial could be from C10 being out of alignment. It would be wise to align the entire set with a signal generator. All trimmable circuits can cause sensitivity to diminish towards one end of the dial if they are out of alignment.

Check every last component, including the volume control, and check all associated connections. Check for leaks and continuity, for condensers and resistors respectively. The growling sounds almost like unwanted oscillation in either the oscillator (1st Detector) or the IF amplifier. If components shifted and are too close to eachother (plate and grid related components or wires), this can cause growling. Replace R1 just to be sure that this doesn't affect the problem. If it doesn't, you can put back in the original component. You can also bridge a new 1 MEG across the old one. It'll work almost the same, since the old one is drifted. ...Or you could bridge with a 3.3 Meg resistor. This may be more accurate.

Thomas

:Hello, how close do the grid caps have to be in tolerance. the one beside r1 says 35mmf which is 35 pico farads, and the other grid cap one is 75 pico farads. As far as station tracking, I dont even have the original knobs and dont know what they should look like. wish I could have a picture of what they should look like. The radio does pick up stations all across the dial, but I dont know if they are where they should be as far as exact location. I did screw in the porcelin trimmer cap(which I just noticed is c10) a bunch which started the radio picking up more stations at the lower and middle end. As far as signal generator aligning, I have one but dont know if it works or even exactly how to use it(that would be a bounus if I did, as I think that would be much fun aligning a set). (my real problem is I should have been born 50 years ago so I could have been a radio repair man)I will check c15 and c9 when I find them.
:When you test any resistor or condenser, you should isolate it from the circuit. To do this, disconnect one or both leads. When making checks, do not touch the meter leads or you'll throw off the reading with the leakage in your hand. It isn't exactly necessary to test condenser capacitance, though it's a plus. Condensers don't usually change capacitance much. What you want to look for is leakage. Any leakage at all is unacceptable. DID YOU CHECK C15 and C9? These are critical (not in value, but in presence), and if they're open or disconnected, they'll allow oscillation.
:
:Regarding those resistors, they have drifted somewhat high, but this drift is not significant in the circuits which they are used in. You may substitute new resistors if you wish. If R5 drifts too high, it'll change the way the detector detects (may cause distortion).
:
:How well does the radio track? Do stations line up fairly well across the dial? No station should be more than about 30 KC off position. If they are off, especially at the low end, C10 may need a re-tune. I just don't see trimmers going out of tune from dropping the set. You'd have to turn the screws a few turns. Still, having sensitivity decrease towards the low end of the dial could be from C10 being out of alignment. It would be wise to align the entire set with a signal generator. All trimmable circuits can cause sensitivity to diminish towards one end of the dial if they are out of alignment.
:
:Check every last component, including the volume control, and check all associated connections. Check for leaks and continuity, for condensers and resistors respectively. The growling sounds almost like unwanted oscillation in either the oscillator (1st Detector) or the IF amplifier. If components shifted and are too close to eachother (plate and grid related components or wires), this can cause growling. Replace R1 just to be sure that this doesn't affect the problem. If it doesn't, you can put back in the original component. You can also bridge a new 1 MEG across the old one. It'll work almost the same, since the old one is drifted. ...Or you could bridge with a 3.3 Meg resistor. This may be more accurate.
:
:Thomas

Well, I was born in 1979, and though I'm far from being an expert, it's possible to learn at any age or time.

Regarding the signal generator, not knowing whether it's working properly is a problem. I own a Sangean AM-FM-Shortwave-Longwave digital tuning radio, which I am lucky enough to own because my neighbor gave it to me. It is otherwise a bit expensive. At any rate, with this radio, or with any radio which has extremely large frequency coverage and a digital tuner, you can use your signal generator as long as it's working to some degree, even if it isn't accurately callibrated anymore. A plus is if the digital radio has super fine tuning. Anyway, with such a radio you can see whether your generator is accurately tuning or not. The Long Wave band allows you to tune in your IF frequency. All other bands allow you to tune in your various antenna and oscillator alignment frequencies.

Alignment of that porcelain trimmer (C10 if I remember correctly) is critical for lower band performance and alignment. If it is off, sensitivity and alignment will suffer tremendously.

If you are not sure if your generator is accurate, you can sort-of assume that it is as long as all discrete components are in working order, and as long as it looks like noone tampered with the coils (this is sometimes hard to tell). You should set your generator to the modulated setting so that a tone is sent out over the frequency which you choose it to broadcast. Try broadcast frequencies (AM and FM, though you want to be sure of the AM since your radio in question is an AM radio) with a good broadcast radio, even if it isn't digital. Place the generator leads next to the radio. Set the generator to variouis frequencies like 600 KC or 1400 KC, and try to tune them in on the radio. Set the generator for the highest RF output and the highest modulation output. If the frequencies align fairly well, then your generator should be in fairly good order. Most modern AM radios use 455 KC as the IF frequency. Tune your generator to 455 KC with your test radio operating. The tone should be heard in the radio right around the 455 marking on your generator. If it isn't approximately in this area, try another radio. If you try several new radios and it doesn't show up with any of them, then your generator may be out of alignment on this band (usually the generator has several frequency bandwidths to choose from). Since you cannot be sure of the IF frequency for any of your "test" radios, though, this does not necessarily mean that the generator is out of alignment. The best way to tell is either with the long wave band of a digital radio or with an electronics shop that is capable of aligning signal generators.

If your generator seems to be working alright, you can align your radio fairly well using this procedure:

Since this is an AC/DC radio with the chassis connected directly to the line cord, work on the chassis on carpeted flooring. DO NOT touch any metal items in the room while holding the chassis. Do not ever touch your chassis and the signal generator at the same time. Connect the signal generator as described in the following, with a .05 MFD 400 WV condenser between each generator lead and the radio. If the radio hums loudly with the generator connected, reverse the radio's line cord. Take a reading from first the radio's chassis and then the generator's chassis to a known ground. Make sure that neither chassis reads 120 volts. If either does, reverse it's line cord.

First, if you are not sure whether your generator works well at IF frequencies, do not align the IF transformers. If your generator uses shielded wire, connect the center wire to the antenna lead of your radio. Connect the shield to the chassis. .05 MFD condensers should be between each lead and its associated connection, as stated previously.

Turn the volume on your radio up as far as it will go. If the radio has frequency coverage listed on a label somewhere on the chassis, use this. Otherwise tune the condenser so that it is completely out of mesh. Set your generator for either 1600 or 1700 KC, depending on how far you want the radio to cover. If the radio wasn't originally meant to go to 1700 KC, setting the end of the dial at this frequency can affect sensitivity uniformity throughout the dial, but since you do not know how far the dial should go, you will just have to guess and go for the coverage you desire. Mis-adjusting this end of the dial won't ruin reception much, so don't worry about it. Adjust the antenna and the oscillator trimmers for the frequency you chose. These trimmers are usually found on the tuning condenser. Once you can hear the tone of your generator, turn down the RF gain on the generator as low as you can turn it so that you can just barely hear the tone in your radio. My EICO generator has a three position gain switch and then a fine tuning knob. Usually gain position number 1 works best for me, and then I adjust the signal strength with the fine tuning knob. Whenever you align the radio to a certain generator frequency, as the signal gets louder, turn down the generator gain until the signal is barely audible again. Continue aligning your radio until your radio is precisely aligned (to the best of your knowledge).

Now turn the tuning condenser so that the plates are completely in mesh. Set the generator for 540 KC. Align C10 so that this frequency comes in loud and clear. Use same generator procedure given above. You may want to first increase generator gain and then bring it back down once you can hear the 540 KC signal.

If things still are odd, you can try setting your generator for 262 KC. With it connected as stated above, align your IF transformers, starting with the one connected to the oscillator. You will have to re-tune the antenna, oscillator, and C10 (oscillator padder) trimmers after adjusting the IF transformers. If you are not sure whether your generator works well at IF frequencies, it is best not to align the IF transformers for now. However, if you can tune in 455 or 455 KC on quite a few modern radios, assume that the generator is fairly well synchronized at this frequency coverage.

Thomas

;hello, I am not sure you can adjust the i.f. transformers as one is on top of the chassis and I am not sure it is adjustable and the other two are underneath in a round can mounted sideways and I dont see anyway these are adjustable either of course I could be wrong
:Well, I was born in 1979, and though I'm far from being an expert, it's possible to learn at any age or time.
:
:Regarding the signal generator, not knowing whether it's working properly is a problem. I own a Sangean AM-FM-Shortwave-Longwave digital tuning radio, which I am lucky enough to own because my neighbor gave it to me. It is otherwise a bit expensive. At any rate, with this radio, or with any radio which has extremely large frequency coverage and a digital tuner, you can use your signal generator as long as it's working to some degree, even if it isn't accurately callibrated anymore. A plus is if the digital radio has super fine tuning. Anyway, with such a radio you can see whether your generator is accurately tuning or not. The Long Wave band allows you to tune in your IF frequency. All other bands allow you to tune in your various antenna and oscillator alignment frequencies.
:
:Alignment of that porcelain trimmer (C10 if I remember correctly) is critical for lower band performance and alignment. If it is off, sensitivity and alignment will suffer tremendously.
:
:If you are not sure if your generator is accurate, you can sort-of assume that it is as long as all discrete components are in working order, and as long as it looks like noone tampered with the coils (this is sometimes hard to tell). You should set your generator to the modulated setting so that a tone is sent out over the frequency which you choose it to broadcast. Try broadcast frequencies (AM and FM, though you want to be sure of the AM since your radio in question is an AM radio) with a good broadcast radio, even if it isn't digital. Place the generator leads next to the radio. Set the generator to variouis frequencies like 600 KC or 1400 KC, and try to tune them in on the radio. Set the generator for the highest RF output and the highest modulation output. If the frequencies align fairly well, then your generator should be in fairly good order. Most modern AM radios use 455 KC as the IF frequency. Tune your generator to 455 KC with your test radio operating. The tone should be heard in the radio right around the 455 marking on your generator. If it isn't approximately in this area, try another radio. If you try several new radios and it doesn't show up with any of them, then your generator may be out of alignment on this band (usually the generator has several frequency bandwidths to choose from). Since you cannot be sure of the IF frequency for any of your "test" radios, though, this does not necessarily mean that the generator is out of alignment. The best way to tell is either with the long wave band of a digital radio or with an electronics shop that is capable of aligning signal generators.
:
:If your generator seems to be working alright, you can align your radio fairly well using this procedure:
:
:Since this is an AC/DC radio with the chassis connected directly to the line cord, work on the chassis on carpeted flooring. DO NOT touch any metal items in the room while holding the chassis. Do not ever touch your chassis and the signal generator at the same time. Connect the signal generator as described in the following, with a .05 MFD 400 WV condenser between each generator lead and the radio. If the radio hums loudly with the generator connected, reverse the radio's line cord. Take a reading from first the radio's chassis and then the generator's chassis to a known ground. Make sure that neither chassis reads 120 volts. If either does, reverse it's line cord.
:
:First, if you are not sure whether your generator works well at IF frequencies, do not align the IF transformers. If your generator uses shielded wire, connect the center wire to the antenna lead of your radio. Connect the shield to the chassis. .05 MFD condensers should be between each lead and its associated connection, as stated previously.
:
:Turn the volume on your radio up as far as it will go. If the radio has frequency coverage listed on a label somewhere on the chassis, use this. Otherwise tune the condenser so that it is completely out of mesh. Set your generator for either 1600 or 1700 KC, depending on how far you want the radio to cover. If the radio wasn't originally meant to go to 1700 KC, setting the end of the dial at this frequency can affect sensitivity uniformity throughout the dial, but since you do not know how far the dial should go, you will just have to guess and go for the coverage you desire. Mis-adjusting this end of the dial won't ruin reception much, so don't worry about it. Adjust the antenna and the oscillator trimmers for the frequency you chose. These trimmers are usually found on the tuning condenser. Once you can hear the tone of your generator, turn down the RF gain on the generator as low as you can turn it so that you can just barely hear the tone in your radio. My EICO generator has a three position gain switch and then a fine tuning knob. Usually gain position number 1 works best for me, and then I adjust the signal strength with the fine tuning knob. Whenever you align the radio to a certain generator frequency, as the signal gets louder, turn down the generator gain until the signal is barely audible again. Continue aligning your radio until your radio is precisely aligned (to the best of your knowledge).
:
:Now turn the tuning condenser so that the plates are completely in mesh. Set the generator for 540 KC. Align C10 so that this frequency comes in loud and clear. Use same generator procedure given above. You may want to first increase generator gain and then bring it back down once you can hear the 540 KC signal.
:
:If things still are odd, you can try setting your generator for 262 KC. With it connected as stated above, align your IF transformers, starting with the one connected to the oscillator. You will have to re-tune the antenna, oscillator, and C10 (oscillator padder) trimmers after adjusting the IF transformers. If you are not sure whether your generator works well at IF frequencies, it is best not to align the IF transformers for now. However, if you can tune in 455 or 455 KC on quite a few modern radios, assume that the generator is fairly well synchronized at this frequency coverage.
:
:Thomas

Well, T1 is your antenna transformer. Adjustments for this (trimmer) are on the antenna section of the tuning condenser. This transformer will be obvious because it will have a lead going to your antenna. T4 is your oscillator transformer. It will have a lead going to the cathode of the 6C6 oscillator/mixer/1st detector tube. One adjustment (trimmer) for this is on the oscillator section of the tuning condenser. The other is C10, the porcelain trimmer. T2 and T3 are your IF transformers. Each should have two screws on the top or side, or perhaps there are four adjustments on the back of the set, similar to 1930s Philco receivers. It is possible that these adjustments must be made with a hex socket (much like a socket wrench) instead of a screw driver. The IF transformers will be obvious in that each has a plate connection. One connects to the plate of the 6C6, and the other connects to the plate of the 6D6. Now oddly enough the tube layout for your radio shows two 6D6 tubes, but the schematic shows a 6C6 for the oscillator and a 6D6 for the IF amplifier. Your radio may have either. Both tubes are physically identical. Electrically one is a sharp cut-off type tube (closely spaced control grid), and the other is a remote cut-off type tube (widely spaced control grid, at least at the top and bottom, and possibly in the middle). Replacing one with the other may or may not affect performance, depending upon the circuit.

Thomas

...As far as signal generator functioning and accuracy go...nowadays.. freq counters are so cheap it doesn't make sense not to own one.
I recently bought a test-bench quality.. GW 100mhz counter for less than $35 on ebay. I aslo just bought a brand new Extech true RMS multimeter for $37.00 as "buy it now" on ebay but saw them getting bought as high bid for as lttle as $9.95 in the auction... AND it measures capacitance AND it is a frequency counter too!! What more could you ask for?

:my radio shack digital meter reads capacitance, and I do believe freq......I also have an o scope...(25meg), wouldnt the oscope allow you to see what the freq is at?
:...As far as signal generator functioning and accuracy go...nowadays.. freq counters are so cheap it doesn't make sense not to own one.
:I recently bought a test-bench quality.. GW 100mhz counter for less than $35 on ebay. I aslo just bought a brand new Extech true RMS multimeter for $37.00 as "buy it now" on ebay but saw them getting bought as high bid for as lttle as $9.95 in the auction... AND it measures capacitance AND it is a frequency counter too!! What more could you ask for?
:

Yes Sean... the scope is great... sure just make sure it's not loading down the oscilator.

And how do I do that, never really got into the oscillator stuff or measuring I.f. freqs. I always wanted to align a set properly, but would need detailed instructions with the stuff I have to do it. Heck maybe the radio I posted about needs just that, an alignment.

Yes Sean... the scope is great... sure just make sure it's not loading down the oscilator.

:Yes Sean... the scope is great... sure just make sure it's not loading down the oscilator.
I forgot to add.. yes, but not a finitely as the freq counter. Unles you only want "close"
remember for scope measurments Freq=1/time and Time=1/freq

BTW.. I think that meter you got at radio shack is the same as mine. Extech?
I first bought mine at Radio shack ($89) but returned it later because the temp sensor was off from calibration by 8 degrees F.
Then I saw it on-line for only $37 shipping included..so I bought it and the temp probe works nicely. I like that meter.

IF alignment is quite easy.
First findout if you IFs are 455kc or whatever...then tune your sig gen to 455kc...un-modulated at first. Then use your freq counter to tune the sig gen right on to 455kc... you mayneed to crank up the output of the sig gen high depending on the sensitivity of your freq counter. Once youve done that and you are happy that the sig gen is in fact spitting out 455kc... Now remember at this point to modulate your sig gen. there is a knob to add 400hz or whatever to the 455kc...then take the modulated sig gen output thru a .05uf cap and connect it into the first stage rf-mixer at the grid or even the plate.
With the radio tuner turned way off the end of the dial. Turn up the volume all the way. If you hear the sig gen sig too loud turn down the output a bit until you can just hear it.
Then go to the 2nd if can and slowly carefull tweak the trimmer caps on the top as the signal gets stronger. Then go to the 1st IF can and do the same. Keep reducing the sig gen output down to minimun as long as you can just hear it. You may repeat the steps until you are certain its right. Thats all.
Go for it.

;So we are just passing the signal by listening to it and tweakin it for best output, and we work backwars....2nd I.F and then 1st I.F. can. Curious though. Why just not put freq counter on each I.F and adjust it to the desired freq, or is the tweaking method the way of observing the best output the radio will give for 262khz(my radios I.F. freq).
Secondly, my sig generator has two 1/4 inch phono jacks. One is rf and the other is af. the rf knob is for power on off of the whole set and rf attenuation. The af has a knob for its on off and attenuation. How would I connect these to produce the modulated 262khz and 400 hz? Do we put a capacitor inbetween the af line and hook it to the rf line and then put that ground of the 2 signals to the radio ground? I am not sure hooking up the two grounds of radio chassis and sig generator is a good idea.......radio doesnt have any isolation transformer
:IF alignment is quite easy.
:First findout if you IFs are 455kc or whatever...then tune your sig gen to 455kc...un-modulated at first. Then use your freq counter to tune the sig gen right on to 455kc... you mayneed to crank up the output of the sig gen high depending on the sensitivity of your freq counter. Once youve done that and you are happy that the sig gen is in fact spitting out 455kc... Now remember at this point to modulate your sig gen. there is a knob to add 400hz or whatever to the 455kc...then take the modulated sig gen output thru a .05uf cap and connect it into the first stage rf-mixer at the grid or even the plate.
:With the radio tuner turned way off the end of the dial. Turn up the volume all the way. If you hear the sig gen sig too loud turn down the output a bit until you can just hear it.
:Then go to the 2nd if can and slowly carefull tweak the trimmer caps on the top as the signal gets stronger. Then go to the 1st IF can and do the same. Keep reducing the sig gen output down to minimun as long as you can just hear it. You may repeat the steps until you are certain its right. Thats all.
:Go for it.
:

:MINE is the one in the yellow plastic case that has a db9 port on it so I can connect it to my computer. How can I even make sure my signal generator is even working?.....and so you are saying that a scope is not the best way to measure freq?
::Yes Sean... the scope is great... sure just make sure it's not loading down the oscilator.
:I forgot to add.. yes, but not a finitely as the freq counter. Unles you only want "close"
:remember for scope measurments Freq=1/time and Time=1/freq
:
:BTW.. I think that meter you got at radio shack is the same as mine. Extech?
:I first bought mine at Radio shack ($89) but returned it later because the temp sensor was off from calibration by 8 degrees F.
:Then I saw it on-line for only $37 shipping included..so I bought it and the temp probe works nicely. I like that meter.

The scope is a bit harder to read accurately.
If you look at the boxes and the tick marks while the signal is displayed you can count boxes and ticks from the start of the signal to the same point at the end of that cycle then multiply those units to the setting of the sweep generator setting youve chosen. That will give you the 'period' of that one cycle in mili or micro seconds or whatever. Then divide that number into the number one to derive the actual frequency in mhz or khz or whatever.
So you see... it's too much like work that way. I'm lazy and perfer accuracy. So I just clip the freq counter onto the signal generator and read the frequency right down to the last few digits of accuracy... Very simple, very accurate.
::
::BTW.. I think that meter you got at radio shack is the same as mine. Extech?
::I first bought mine at Radio shack ($89) but returned it later because the temp sensor was off from calibration by 8 degrees F.
::Then I saw it on-line for only $37 shipping included..so I bought it and the temp probe works nicely. I like that meter.

Your IF is 262KC.

I usually have luck injecting the IF right at the antenna terminals. You can also use the 6C6 grid connection on top.

Thomas

Well I replaced two caps underneath and for some reason, it seemed to solve the odd ball growling or whatever noise........so I was listening to it (it almost sounded normal(a very small amout of distortion), when it made a single popping noise and started playing way distorted.....hmmm not good, bad connection, resistor, cold solder joint, or the dreaded I.F. can....but if it does pop and stay there, I should be able to check voltages and see which one goes off spec, if only I can remember what voltages to check for...lol...........biasing if I remember correctly
::Your IF is 262KC.
:
:I usually have luck injecting the IF right at the antenna terminals. You can also use the 6C6 grid connection on top.
:
:Thomas

:Can a furnace turning on and running make this radio play distorted???Like maybe its on the same circuit.

:Well I replaced two caps underneath and for some reason, it seemed to solve the odd ball growling or whatever noise........so I was listening to it (it almost sounded normal(a very small amout of distortion), when it made a single popping noise and started playing way distorted.....hmmm not good, bad connection, resistor, cold solder joint, or the dreaded I.F. can....but if it does pop and stay there, I should be able to check voltages and see which one goes off spec, if only I can remember what voltages to check for...lol...........biasing if I remember correctly
:::Your IF is 262KC.
::
::I usually have luck injecting the IF right at the antenna terminals. You can also use the 6C6 grid connection on top.
::
::Thomas

Any switch opening or closing creates amplitude modulation. The signal is very wide in band width, which is why it is picked up by all sorts of radios--short wave, standard broadcast, FM if FM didn't have a limiter stage which supresses static. Your furnace could in fact be making the popping sound.

Make sure that all replacement condensers are of proper voltage (over 400 WVDC is ideal). Check all condensers again for shorts and leakage. Check even the new ones. Disconnect each. If you have distortion, something is probably wrong with the radio. Check even in the audio section. It is possible that the furnace would create momentary distortion if it affected the gain in the RF stages.

Thomas

:WELL, the radio operates as all my radios do.......they hate comprssor motors and other things turning on and off.....as far as the pop and distortion, it was a new cap with wires too long......too long and the chassis moves.............SHORT.....so we are still dealing with that wind whistle on certain stations......it seems to get less after it runs for a while. right now its real soft and low in growl. So when I am confident of alignment procedures and what to adjust......thats the next step. As I dont see any of the transformers having a slug to adjust.
::Any switch opening or closing creates amplitude modulation. The signal is very wide in band width, which is why it is picked up by all sorts of radios--short wave, standard broadcast, FM if FM didn't have a limiter stage which supresses static. Your furnace could in fact be making the popping sound.
:
:Make sure that all replacement condensers are of proper voltage (over 400 WVDC is ideal). Check all condensers again for shorts and leakage. Check even the new ones. Disconnect each. If you have distortion, something is probably wrong with the radio. Check even in the audio section. It is possible that the furnace would create momentary distortion if it affected the gain in the RF stages.
:
:Thomas

You can try putting aluminum foil around the RF tubes. Connect this to the chassis--leave a bit hanging down that'll brush firmly against the chassis. It may reduce growl. In this case your radio may be missing shields.

Thomas

: Well It does have shields. Maybe they are not grounded good enough, your foil idea which I have done in the past, would tell me if the shields are working, or maybe run a jumper from shield to ground.
:You can try putting aluminum foil around the RF tubes. Connect this to the chassis--leave a bit hanging down that'll brush firmly against the chassis. It may reduce growl. In this case your radio may be missing shields.
:
:Thomas

:If I were to check biasing voltages for this set, what ones should I be concerned about. I noticed that this set has ac and dc voltage checks according to the schematic.
::You can try putting aluminum foil around the RF tubes. Connect this to the chassis--leave a bit hanging down that'll brush firmly against the chassis. It may reduce growl. In this case your radio may be missing shields.
:
:Thomas

If the set has shields, then you don't need to mess with aluminum foil. The bias voltages you should be concerned are those on the control grids. The only way to measure some of these is with a vacuum tube volt meter. They are direct current.

Thomas

:Ok I have a vaccumm tube volt meter. which ones are the control grids and what voltage values should they be or am I supposed to test for current?
:If the set has shields, then you don't need to mess with aluminum foil. The bias voltages you should be concerned are those on the control grids. The only way to measure some of these is with a vacuum tube volt meter. They are direct current.
:
:Thomas

Control grids don't usually conduct current. I would have to examine your diagram to see what the voltages should be. I'm going to sleep right now. The grids usually are some negative number, though. I don't know if grid bias would affect a growling sound much, but perhaps it would.....seems it might if it aided or supressed unwanted feedback, depending upon its voltage.

Keep in mind that if you replaced a condenser with a smaller value by accident, this would affect performance as well. If a screen grid is being fed B+ through a resistor, and there's supposed to be a .1 MFD condenser on the screen grid, accidently replacing this with a .01 MFD condenser will allow more fluctuation in the circuit, and may allow unwanted oscillation/other noises.

Thomas

Make sure, too, that you and other people in the house aren't running televisions. This will cause growl and strange noises in the radio. Do not run microwaves or dimmers or computers.

Make sure that antenna leads aren't too close to anything else. Make sure that your antenna coil isn't open. Keep grid and plate wires far apart.

Thomas

:Sounds like what you are saying is that the I.F. transformers have to be adjustable themselves? I took the rectangular can off the one next to the 6d6 on top of the chassis and so far dont see any adjustment. There is a 1/16 inch maybe a little bigger in the wood on the top of the coil but I dont see any adjustment yet. I stuck a screwdriver in the hole and it bottoms out but doesnt seem to grip anything, maybe it is an allen.(not sure if theres even anything there to adjust). this can gridcap goes to the 6d6 so there must be one for the 6c6???......its grid cap comes from the tuning condenser......so is there only 1 I.F. to adjust?, but you said t2 and t3 are the I.F.s. Well then one of the I.F's must be under the chassis because theres only one can on top....well that leaves the two round ones underneath the chassis
:Make sure, too, that you and other people in the house aren't running televisions. This will cause growl and strange noises in the radio. Do not run microwaves or dimmers or computers.
:
:Make sure that antenna leads aren't too close to anything else. Make sure that your antenna coil isn't open. Keep grid and plate wires far apart.
:
:Thomas

I just opened up one of the transformers underneath the chassis and they are not adjustable eigher. the only one I am not sure of is the one on top between the 6c6 and the 6d6(I opened this one also and the only possable adjustment is down through the wood dowel, but I put a screwdriver down it and didnt feel any sort of slot, hex or any metal for that matter, the screwdriver just bottomed out on something but I dont know if its wax or what. why would they fill a adjustment hole......not sure if thats what they did or not. also not sure if I even want to try and dig out whatever that is. the driver stops halfway down the dowel

:::Sounds like what you are saying is that the I.F. transformers have to be adjustable themselves? I took the rectangular can off the one next to the 6d6 on top of the chassis and so far dont see any adjustment. There is a 1/16 inch maybe a little bigger in the wood on the top of the coil but I dont see any adjustment yet. I stuck a screwdriver in the hole and it bottoms out but doesnt seem to grip anything, maybe it is an allen.(not sure if theres even anything there to adjust). this can gridcap goes to the 6d6 so there must be one for the 6c6???......its grid cap comes from the tuning condenser......so is there only 1 I.F. to adjust?, but you said t2 and t3 are the I.F.s. Well then one of the I.F's must be under the chassis because theres only one can on top....well that leaves the two round ones underneath the chassis
::Make sure, too, that you and other people in the house aren't running televisions. This will cause growl and strange noises in the radio. Do not run microwaves or dimmers or computers.
::
::Make sure that antenna leads aren't too close to anything else. Make sure that your antenna coil isn't open. Keep grid and plate wires far apart.
::
::Thomas

:Well I tried the sig gen and it does output 262khz. I did hook the center lead of gen to the radio antenna. and when I turned the gen freq knob around 262khz(rough guess), it would hear the radio make and audible noise, so wheather or not this is the tone I am supposed to be hearing or not. I did have the tuning dial all the way to one end....in mesh, gen centerlead connected to radio antenna and ground left near radio...as far as I.F transformer adjustment who knows....the coils themselves arent adjustable so it must be the tunning condenser trimmers and the c10 that do the adjusting

:Well, T1 is your antenna transformer. Adjustments for this (trimmer) are on the antenna section of the tuning condenser. This transformer will be obvious because it will have a lead going to your antenna. T4 is your oscillator transformer. It will have a lead going to the cathode of the 6C6 oscillator/mixer/1st detector tube. One adjustment (trimmer) for this is on the oscillator section of the tuning condenser. The other is C10, the porcelain trimmer. T2 and T3 are your IF transformers. Each should have two screws on the top or side, or perhaps there are four adjustments on the back of the set, similar to 1930s Philco receivers. It is possible that these adjustments must be made with a hex socket (much like a socket wrench) instead of a screw driver. The IF transformers will be obvious in that each has a plate connection. One connects to the plate of the 6C6, and the other connects to the plate of the 6D6. Now oddly enough the tube layout for your radio shows two 6D6 tubes, but the schematic shows a 6C6 for the oscillator and a 6D6 for the IF amplifier. Your radio may have either. Both tubes are physically identical. Electrically one is a sharp cut-off type tube (closely spaced control grid), and the other is a remote cut-off type tube (widely spaced control grid, at least at the top and bottom, and possibly in the middle). Replacing one with the other may or may not affect performance, depending upon the circuit.
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:Thomas

You can't find any adjustments on the IF transformers? There aren't any holes with screws in them? There aren't any wires coming off of the IF transformers going to trimmer condensers???? Maybe you should send some pictures of your chassis (like 6 to 10 of different angles). The trimmers on your tuning condenser are not for the IF adjustment. One is for the antenna section, which is usually adjusted either for 1400 KC or for the frequency at the end of the dial (with the plates out of mesh). The oscillator trimmer, which is for the other section of the tuning condenser, is adjusted in the same manner.

The condenser plates should be out of mesh when you make IF transformer adjustments.

Did you see that I found you your tube tester update?

Thomas

:Yes I did thanks....havnt tried it out yet.I hope it will fall under the "will test all old radio tubes category now"
::Did you see that I found you your tube tester update?
:
:Thomas

Before you rely on that tube tester, check all of the resistors underneath. They should be right on value. If not, replace them with good quality new resistors. If you can, use wire wound units for the higher wattage ones. Otherwise stick to carbon composition or carbon film. Carbon film will probably provide the most accuracy. Your tube tester doesn't have to be millitary accurate, obviously, because it's only telling you good, weak, or bad, but you want all of the tubes which should register one way or another to do so. Drifted resistors usually cause readings in one scale (selector switch position) or another to be low, or in the "replace" region. As always, in the end let your radio be the final tester. If you are having trouble, first check your resistors and condensers, and your coils...etc. Then test your tubes if you still have trouble. Replace all which are weak or bad. If this corrects the problem, put back in each weak or bad tube, one at a time, to see if it is in fact bad. If not, save the ones which still work for either this set or another one.

Another thing....the wiring on this tester doesn't do too well with high current low voltage tubes like the 24 and the 27. I find that with the line voltage set and the tube running, the voltage is a bit lower at the socket than it is at the transformer. It's right on at the transformer. Usually these tubes have pins 1 and the other end pin as the filament pins (pin 4, 5, 6, or 7, depending upon whether the tube is a 4, 5, 6, or 7 pin tube). For each socket you may want to rewire with heavier wire to the filament pins so that your readings with these tubes are more accurate. When the tester is set to line voltage, the 110 volt setting puts out exactly 115 volts (don't ask why they labeled it 110). All other voltages are exact, too. Of course with modern line voltage, the voltages in your radio may be a bit higher. For accurate tests, though, you should always re-callibrate the line adjustment for each tube while the filament is running. The tests depend upon accurate voltage within the tester. Increasing the line voltage to compensate for the voltage drop to the filament of say a #27 tube, will increase the B voltage too much, and will give you high readings. Again, though, your radio should be the final test, so I don't know why I'm spending so much time on this. The tester just gives you an idea as to which tube might be at fault.

Thomas

:its a low growling squeal, no powersupply hum, that I have under control. and yes I can turn down the squeal with the volume control
:Does it hum like power supply hum or does it hum like poor shielding in the audio? Is the volume control on the 1st audio tube or is it on the antenna circuit? Can you turn down the hum with the volume control? Check your wiring under the chassis. Check for shorts and broken wires. Test your tubes. See to it that none have element to element shorts.
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:What is the model number of your set? It'd be nice to see a schematic so that I could see how the filaments are wired and if your modification affected anything in the power supply.
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:You shouldn't have to use electrolytics back to back if your diode is working properly. Did you use a regular diode or a zener diode? A zener diode will allow current to pass in both directions. Your diode must have absolutely no leakage in the reverse direction. Your meter should read infinity. Anything less is unacceptable. Then all you need to do is observe polarity across the tube filaments and then install the electrolytic in this direction. Use a 200 WV electrolytic.
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:Thomas

Well first of all I was adding up the total voltage consumed by the heaters....69 volts so the reasoning is that I need to DROP and additionall 46 volts to equall supplied wall voltage.
:First, don't try to measure the voltage across the heater string (after the diode). Even if you have a true RMS meter, it will give you a low number because the meter will assume that the waveform is symmetrical, which it is not.
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:A diode by itself, without any capacitor, with reduce the effective RMS AC voltage to 70%: 120V x 70% = 84V. That's the RMS voltage that will appear across the heater string, even though your meter will say it's less.
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:Sean, you said that the heater string wants to see 69V. Well, the diode by itself and no cap, will put out 120V x 70% = 84V - WHICH IS MORE THAN THE VOLTAGE YOU DESIRE (69V). So I cannot understand why you think you need to boost the voltage - it's already too high!
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:Let's not gum this anymore until Sean works thru the reasoning here - we're just going around in circles. And, Sean, don't use your meter - it's worthless for what your trying to measure.