Here is my advice to you.
It's free, and worth every cent of it :>)
First of all, look at the radio in three sections, rather than one. There is the power supply, which I understand you have met, the audio stages, and the radio itself, or the RF stages. The power supply is the easiest to fix, even though some will disagree with that. The filter caps are to be assumed bad at the beginning. there are some bypass caps and things that can give you fits, but for the most part once you have the Voltages right and the caps replaced, you are home free. You are not stupid getting shocked at first. You are merely learning where not to touch.
You have a tuning eye on this radio. If the RF stages are getting to the first audio tube, you have diode plates in the tube that are used to rectify the RF to make audio, and porvide a DC Voltage for Automatic Volume Control, or AVC. If the tuning eye closes and opens as you tune the dial, your RF stages are getting to the second detector, the triode with the diode plates, so you have something good going on there.
So, get your power supply Voltages right, the Audio working, and with luck the RF will be OK. If not, there is a lot of help here waiting to be called on.
Lewis L.
Thank you, your suggestions are very insightful. Three sections, power, RF, and IF. I was reading an article and it mentioned about using a signal generator and tracing the signal through the various radio components to see where the signal is being stopped or is weak. That means buying a signal generator and an oscilloscope to do this work, is there a better method? I have a VOM meter and a PACO tube tester already. But pleas tell me more about the transistor radio and the ear phone, it sounds interesting and affordable. Again thank you.
Dave B.
If these things don't bring in nice loud music (or bad talk radio), then follow what everyone else said. It is wise to get a signal generator and all that good stuff anyway. It'll come in handy in the future, and may help you fine tune your current radio if it needs fine tuning. I recommend that you first try to very carefully peak the IF transformers without a signal generator, if you manage to get the radio to play well. Touch them up very slightly (sometimes they get slightly out of alignment after 60 years). The reason why I recommend touching them up without a signal generator is that signal generators aren't always extremely accurate. I usually tune mine in with a digital radio first before using it to align a radio. If the generator is slightly off, and you use it to align a perfectly working radio, you may make things slightly worse. However, for radios that are severely out of alignment, a slightly inaccurate signal generator is the greatest thing, even if it isn't perfect.
T
If these things don't bring in nice loud music (or bad talk radio), then follow what everyone else said. It is wise to get a signal generator and all that good stuff anyway. It'll come in handy in the future, and may help you fine tune your current radio if it needs fine tuning. I recommend that you first try to very carefully peak the IF transformers without a signal generator, if you manage to get the radio to play well. Touch them up very slightly (sometimes they get slightly out of alignment after 60 years). The reason why I recommend touching them up without a signal generator is that signal generators aren't always extremely accurate. I usually tune mine in with a digital radio first before using it to align a radio. If the generator is slightly off, and you use it to align a perfectly working radio, you may make things slightly worse. However, for radios that are severely out of alignment, a slightly inaccurate signal generator is the greatest thing, even if it isn't perfect.
T
However..Back in the day... radio bench techs worked wonders with much less sophisticated gear than we have today...and they got the job done quite well anyway.
However nowadays...mostly everything in the way of quality test equipment that you could ever hope for is dirt cheap today and can be acquired on Ebay very easily.
I own three pieces of test equipment that are very valuable bench tools to me for aligning any typical 1930-50s radio such that it can be "perfectly" aligned quite easily.
1. Digital Multimeter =$45
2. Signal Generator = $30
3. Digital freq counter =$30
(For IF alignment I follow these steps:)
After recapping the entire radio I open the tunning condenser plates fully.
Then I connect my digital frequency counter to my (un-modulated) signal generator and adjust the signal generator so the frequency counter reads exactly 455khz.
Then (with audio modulation now applied)I inject that 455khz signal at the antenna or 1st IF stage via a small coupling capacitor.
I keep the signal generator output level as low as possible to just hear that audio tone.
Then I connect my DMM to the AVC circuit and while tweaking the trimmers on the IF cans in sequence ( 2nd IF first) I watch my DMM and peak it for a max negative voltage on the AVC line( typically -2 to -7 volts or so but the exact value is not important)
(When the IF transformers are most properly aligned they will pass the greatest amount of 455khz signal, therefore the AVC feed back line will be generating the most amount of negative AVC voltage at that time also. So this is the best and easiest way to judge the IF bandpass performance since our ears are not as exacting and you also won't need to crank up the loud speaker such that you wake up the neighbors)
When I am certain that I have properly tweaked the IFs I then disconnect the signal generator and tune to a typical local station.
If I tune the radio to an 1160khz radio station for example, the radio's local oscillator should be producing a hetrodyning frequency at exactly 455khz above that or 1615khz.
So to confirm this, I then place a pickup loop lead from my frequency generator close to the local oscillator and watch the frequency counter numbers at the same time as I continue to monitor the DMM connected to the AVC line.
While slowly "tuning-in" the station's signal, the DMM on the AVC line should produce a peak negative voltage ( you should be able to hear that the station seems properly tuned-in as well at this time)
Also at this time I watch my digital frequency counter and see that the local oscillator is producng EXACTLY 1615khz.
The fact that the AVC line is peaked for max negative voltage at the EXACT same moment that the local oscillator is producing a frequency of exactly 455khz higher than the radio station will confirm to you that your IF circuit is optimally aligned.
If you plut an earphone plug in the earphone jack of a portable transistor radio, the Voltage level will be just about right to inject audio across the volume control. I say a small transistor because the thing is battery operated, so you don't have to worry about a transformerless radios (with one side of the power line connect to the chassis) causing a small event in your face. Being batery operatec, they won't have hum, and the audio quality is surprisingly good if they are hooked up to a good speaker. If nobody has tried for a "good deed for the day" prize by tightening all the loose screws on thae IF transformers, the RF section should give the least trouble, as there is not too much hard work being done there and components are less likely to be altered by heat. As I write this, I remember the last old radio I restored had as the main problem a shorted bypass capacitor on the IF amp screen, so RF, Osc, and IF stages are not immune from being the problem, but if you get the power and audio sections working right first, the kRF stages will be a lot easier to work on.
Lewis L.
However..Back in the day... radio bench techs worked wonders with much less sophisticated gear than we have today...and they got the job done quite well anyway.
However nowadays...mostly everything in the way of quality test equipment that you could ever hope for is dirt cheap today and can be acquired on Ebay very easily.
I own three pieces of test equipment that are very valuable bench tools to me for aligning any typical 1930-50s radio such that it can be "perfectly" aligned quite easily.
1. Digital Multimeter =$45
2. Signal Generator = $30
3. Digital freq counter =$30
(For IF alignment I follow these steps:)
After recapping the entire radio I open the tunning condenser plates fully.
Then I connect my digital frequency counter to my (un-modulated) signal generator and adjust the signal generator so the frequency counter reads exactly 455khz.
Then (with audio modulation now applied)I inject that 455khz signal at the antenna or 1st IF stage via a small coupling capacitor.
I keep the signal generator output level as low as possible to just hear that audio tone.
Then I connect my DMM to the AVC circuit and while tweaking the trimmers on the IF cans in sequence ( 2nd IF first) I watch my DMM and peak it for a max negative voltage on the AVC line( typically -2 to -7 volts or so but the exact value is not important)
(When the IF transformers are most properly aligned they will pass the greatest amount of 455khz signal, therefore the AVC feed back line will be generating the most amount of negative AVC voltage at that time also. So this is the best and easiest way to judge the IF bandpass performance since our ears are not as exacting and you also won't need to crank up the loud speaker such that you wake up the neighbors)
When I am certain that I have properly tweaked the IFs I then disconnect the signal generator and tune to a typical local station.
If I tune the radio to an 1160khz radio station for example, the radio's local oscillator should be producing a hetrodyning frequency at exactly 455khz above that or 1615khz.
So to confirm this, I then place a pickup loop lead from my frequency generator close to the local oscillator and watch the frequency counter numbers at the same time as I continue to monitor the DMM connected to the AVC line.
While slowly "tuning-in" the station's signal, the DMM on the AVC line should produce a peak negative voltage ( you should be able to hear that the station seems properly tuned-in as well at this time)
Also at this time I watch my digital frequency counter and see that the local oscillator is producng EXACTLY 1615khz.
The fact that the AVC line is peaked for max negative voltage at the EXACT same moment that the local oscillator is producing a frequency of exactly 455khz higher than the radio station will confirm to you that your IF circuit is optimally aligned.
David:
Here's some high-tech alignment tips that I use that may help you:
However..Back in the day... radio bench techs worked wonders with much less sophisticated gear than we have today...and they got the job done quite well anyway.
Nowadays...mostly everything in the way of quality test equipment that you could ever hope for is dirt cheap today and can be acquired on Ebay very easily.
I own three pieces of test equipment that are very valuable bench tools to me for aligning any typical 1930-50s radio such that it can be "perfectly" aligned quite easily.
1. Digital Multimeter =$45
2. Signal-Generator = $30
3. Digital Frequency-Counter =$30
(For IF alignment I follow these steps:)
After recapping the entire radio I open the tuning condenser plates fully.
Then I connect my digital Frequency-Counter to my (un-modulated) Signal-Generator and adjust the Signal-Generator so the Frequency-Counter reads exactly 455khz.
Then (with audio modulation now applied)I inject that 455khz signal at the antenna or 1st IF stage via a small coupling capacitor.
I keep the Signal-Generator output level as low as possible to just hear that audio tone.
Then I connect my DMM to the AVC circuit and while tweaking the trimmers on the IF cans in sequence ( 2nd IF first) I watch my DMM and peak it for a maximum negative voltage on the AVC line( typically -2 to -7 volts or so but the exact value is not important)
(When the IF transformers are most properly aligned they will pass the greatest amount of 455khz signal, therefore the AVC feed back line will be generating the most amount of negative AVC voltage at that time also. So this is the best and easiest way to judge the IF bandpass performance since our ears are not as exacting and you also won't need to crank up the loud speaker such that you wake up the neighbors)
When I am certain that I have properly tweaked the IFs I then disconnect the Signal-Generator and tune to a typical local station.
If I tune the radio to an 1160khz radio station for example, the radio's local oscillator should be producing a hetrodyning frequency at exactly 455khz above that or 1615khz.
So to confirm this, I then place a pickup loop lead from my digital Frequency-Counter close to the local oscillator and watch the Frequency-Counter numbers at the same time as I continue to monitor the DMM connected to the AVC line.
While slowly "tuning-in" the station's signal, the DMM on the AVC line should produce a peak negative voltage ( you should be able to hear that the station seems properly tuned-in as well at this time)
Also at this time I watch my digital Frequency-Counter and see that the local oscillator is producng EXACTLY 1615khz.
The fact that the AVC line is peaked for max negative voltage at the EXACT same moment that the local oscillator is producing a frequency of exactly 455khz higher than the radio station carrier will confirm to you that your IF circuit is optimally aligned.
Lewis again:
Everything above is correct, but I was telling you some things you can do with what you have at hand now. For instance, you can check out the local oscillator with a transistor radio by placing the transistor near the radio under repair, and tuning it to a quiet place on the high end of the dial. When you tune your radio to a frequincy 455 kHz below that of the transistor, you should hear the local oscillator as you tune the radio under test back and forth.
Again, ss I have said, you can take the transistor and use the speaker output that is available at the earphone jack, and connect across the volume control, you will have the equivalent of the "Audio Out" of a signal generator. A VOM can check for Voltage on the screens and plates of all of the tubes, but the AVC voltage mentioned above must be checked with a DMM or VTVM. While the radio may play weakly with a defective component, there is one thing about the local oscillator. No local oscillator, no Nuttin' Honey! The signal comes in at a frequency determined by the station, is mixed by a locally generated signal 455 kHz higher from the LO, mixed in the same tube to form an intermediate frequency (IF) of 455 kHz. The IF amplifier is looking for this 455, and nothing else. No 455 into it, nothing out of it, no matter how powerful the input is. Since the LO runs from 1005 Khz to 2055 kHz, the 1005 to 1600 is able to be picked up on another radio if it is close to the the test radio. By the way, you have a sort of VTVM in the tuning eye, already connected to the AVC line. I hope this gets you along a little bit. I have gotten too long winded, but I remember the days before television, in the living room with my family, listening to the radio, and I think life had a lot of things going for it that are gone forever today. Hey, if anyone is interested in restoring these old boxes that gave so much pleasure to people in the old days, I will tell all I know to help.
Lewis L.
Thank you for the pl ether of information, some terms I don't even understand, but that all part of the learning process. My next purchase will be a signal generator, the VOM I have and I also have a PACO tube tester so that help as well. Once I am in full operation I will attempt some of your suggestions. When I worked with the radio, and got another belt,
the tuning tube did not respond as I tuned the radio so it seems like little or no signal is coming in. The power supply, and tubes, check out fine, and most capacitors were replaced, but not all. When I turn the radio on I set a very low volume hum and turning up the volume control does not help. I don't know which direction to go next except perhaps to use a signal generator and attempt to introduce and trace a signal through the radio and find where the signal stops or weakens. Any of you guys want to fly to Plymouth, MA and help me. I'll put you up and show you around the town, ya I didn't think so, I tried. Thanks again and keep the info coming. What has two legs, two arms and it's hair standing on end, me when I touch the wrong thing in the radio,
Another observation from Lewis L.
You have, on the front of the radio, if I am correct, a switch marked "Television, Radio, Victrolia", while on the back, you have two jacks marked "Telev. audio input, and victrola" This switch is the input to the audio amplifier. The left position connects the volume control to the Victrolia jack, while the cinter position is the radio, and the right is the "Television" jack. Here is an excellent place to test the audio amplifier, just plug something into a jack, select the jack with the selector switch, and check for audio. A finger applied to the center of the jack should provide a 60 Hz buzz. The fact that you hear a slight hum indicates at least the output stage, if not the whole audio amplifier is working.
Lewis L.