Kirk
You're joking, right ?
Google MP3 Player...
As for the second question. You can add an audio jack to the volume control and have some way to disable the audio coming from the radio's first AF stage to the said volume control using a good isolation method (say a small audio transformer discarded from a defunct early type solid-state radio).
There's been a lenghty discussion about this last month with some very bad advice given. Everyone (but the OP) agreed that is was safer to use good isolation between the MP3 player and the radio.
I prefer using a small am transmitter. A single transistor and a few parts,powered by a 9V battery, would be the perfect solution (I can direct you to a schematic). No modification to the radio is necessary and the MP3 player can be used on any AM radio, or FM if an FM transmitter is used. Parts from, again, a defunct AM solid state radio can be used.
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:You're joking, right ?
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:Google MP3 Player...
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:As for the second question. You can add an audio jack to the volume control and have some way to disable the audio coming from the radio's first AF stage to the said volume control using a good isolation method (say a small audio transformer discarded from a defunct early type solid-state radio).
:
:There's been a lenghty discussion about this last month with some very bad advice given. Everyone (but the OP) agreed that is was safer to use good isolation between the MP3 player and the radio.
:
:I prefer using a small am transmitter. A single transistor and a few parts,powered by a 9V battery, would be the perfect solution (I can direct you to a schematic). No modification to the radio is necessary and the MP3 player can be used on any AM radio, or FM if an FM transmitter is used. Parts from, again, a defunct AM solid state radio can be used.
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Here it is: http://www.techlib.com/electronics/amxmit.htm
You can go for the first schematic, but I prefer the one titled "phono oscillator". Very simple to build using salvaged parts. Works barely a few feet but that isn't a problem in itself as the goal is to modulate from an MP3 player (which is portable) resting besides the radio. The simple version works wonder and yes it is nice to listen to some period music through an old radio.
:I've heard of these MP3 players but I just don't have a use for them.
I guessed that. There is a website with thousands of MP3 audio files sampled from 78 records. If I find it, I'll post it here.
Hope this helps.
:: What is a MP3 player?
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:You're joking, right ?
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:Google MP3 Player...
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:As for the second question. You can add an audio jack to the volume control and have some way to disable the audio coming from the radio's first AF stage to the said volume control using a good isolation method (say a small audio transformer discarded from a defunct early type solid-state radio).
:
:There's been a lenghty discussion about this last month with some very bad advice given. Everyone (but the OP) agreed that is was safer to use good isolation between the MP3 player and the radio.
:
:I prefer using a small am transmitter. A single transistor and a few parts,powered by a 9V battery, would be the perfect solution (I can direct you to a schematic). No modification to the radio is necessary and the MP3 player can be used on any AM radio, or FM if an FM transmitter is used. Parts from, again, a defunct AM solid state radio can be used.
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:You're joking, right ?
:
:Google MP3 Player...
:
:As for the second question. You can add an audio jack to the volume control and have some way to disable the audio coming from the radio's first AF stage to the said volume control using a good isolation method (say a small audio transformer discarded from a defunct early type solid-state radio).
:
:There's been a lenghty discussion about this last month with some very bad advice given. Everyone (but the OP) agreed that is was safer to use good isolation between the MP3 player and the radio.
:
:I prefer using a small am transmitter. A single transistor and a few parts,powered by a 9V battery, would be the perfect solution (I can direct you to a schematic). No modification to the radio is necessary and the MP3 player can be used on any AM radio, or FM if an FM transmitter is used. Parts from, again, a defunct AM solid state radio can be used.
:Seriously,Jay W, np bull s * * * have heard of those Mp3 plays buy not know exactly what they are???
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:There's been a lenghty discussion about this last month with some very bad advice given. Everyone (but the OP) agreed that is was safer to use good isolation between the MP3 player and the radio.
:
:I prefer using a small am transmitter. A single transistor and a few parts,powered by a 9V battery, would be the perfect solution (I can direct you to a schematic). No modification to the radio is necessary and the MP3 player can be used on any AM radio, or FM if an FM transmitter is used. Parts from, again, a defunct AM solid state radio can be used.
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Guys, you must be kidding... Have you seen the PHONO connector on the back of the radio? Connect you MP3 or CD or whatever player to it, switch radio to PHONO and enjoy the music. The only question is - how to make it mono from stereo? Just connect one 1000 Om resistor to each player's output cable and connect the other resistors to make it momo...
Use it at your own risk.
If you were to switch the existing phono-input switch to the "phono" position you can see how the circuit modification example shown below would act.
Try it at your own risk.
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:If you were to switch the existing phono-input switch to the "phono" position you can see how the circuit modification example shown below would act.
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:Try it at your own risk.
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Kirk
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:I installed the MP3 jack per Peters instructions and I also put new capacitors in the entire set. The set works (haven't tried the MP3 part yet) but there is a buzz or hum that is proportional to the volume. It's not there when volume is all the way down and increases as I increase the volume. I get good reception and all stations come in clear. Just has that noise when I turn the volume up and down. Rechecked all my capacitors and the MP3 jack installation and everything is hooked up right. What did I do wrong?
Kirk
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:Kirk
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I didn't specify it in my drawing but it is best to use shielded cable leads between the radio and the Mp3-jack. ( I'll modify the drawing)
The outer shield around each lead is just to block noise and it should be grounded at both ends.
I use some tiny coax wire I have around here.
It often happens the the long leads going out to the Mp-3 jack can easily pick up some AC hum.
To determine if THAT is the cause. Disconnect the long leads from your volume pot point ...at and restore the normal connection to see if the hum goes away.
If that's it ....then careful use of shielded cable to the jack and returning from the jack should solve it.
Take it one step at a time testing as you go.
Good luck.
::
::Kirk
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:Hi Kirk:
:I didn't specify it in my drawing but it is best to use shielded cable leads between the radio and the Mp3-jack. ( I'll modify the drawing)
:The outer shield around each lead is just to block noise and it should be grounded at both ends.
:
:I use some tiny coax wire I have around here.
:
:It often happens the the long leads going out to the Mp-3 jack can easily pick up some AC hum.
:
:To determine if THAT is the cause. Disconnect the long leads from your volume pot point ...at and restore the normal connection to see if the hum goes away.
:
:If that's it ....then careful use of shielded cable to the jack and returning from the jack should solve it.
:
:Take it one step at a time testing as you go.
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:Good luck.
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:I guess I have a problem somewhere else. I took the MP3 jack out of the circuit and I still have the noise. Checked voltages for the heck of it and they all look good.
Kirk
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:Kirk
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Try to localize it.
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::Kirk
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:Actually didn't have to even remove it just turn phono sw to radio right?
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:But to help trace your hum try pulling the 1st audio amp. 6jg5 tube... or ground the grid where r4 and the vol control feed into that grid.
:Try to localize it.
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:Peter, I pulled the 1st audio 6J5 and everything went away. The music and the hum. So then I pulled the 6J5 detector and I still have music and hum. Little difference in the sound but pretty much the same. I tried swapping out both these tubes and that made no difference.
Kirk
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:Kirk
Try to localize where the hum is coming from.
To see if it comes from BEFORE the 1st audio AMP 6j5 ground that grid.
If you still have some hum try grounding the input grid of the next stage .. the inverter 6f8 .. and so on.
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:The leads on C14 are quite short the way it's in the radio. About 1/4" long on each end. When you say ground the grid of the first audio 6J5 to see if the hum goes away, and the hum does go away when I do this, does this mean that the problem is before the audio 6J5? If it is before the audio 6J5 does this mean it's coming from the 3rd IF or something before that?
Kirk
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::The leads on C14 are quite short the way it's in the radio. About 1/4" long on each end. When you say ground the grid of the first audio 6J5 to see if the hum goes away, and the hum does go away when I do this, does this mean that the problem is before the audio 6J5? If it is before the audio 6J5 does this mean it's coming from the 3rd IF or something before that?
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:Kirk
:Something before that .. yes.
::Something before that .. yes.
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:You can try grounding the grids of each previous stage to see if it's before that stage or not ...working back toward the RF input section.
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:::Something before that .. yes.
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::You can try grounding the grids of each previous stage to see if it's before that stage or not ...working back toward the RF input section.
::
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:You can also eliminate the entire RF area by switching into "phono".
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:If the hum is still there while in "phono" then the RF/IF section ...is ok and the problem lies somewhere with those tone push button contacts or circuitry.
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:I'm not the most experienced radio guy. This is my third one. In phono position there's no hum. Also when I switch to any other band besides BC band the hum is gone. I'll check that tone switch.
Kirk
:::Something before that .. yes.
::
::You can try grounding the grids of each previous stage to see if it's before that stage or not ...working back toward the RF input section.
::
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:You can also eliminate the entire RF area by switching into "phono".
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:If the hum is still there while in "phono" then the RF/IF section ...is ok and the problem lies somewhere with those tone push button contacts or circuitry.
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:Well Im really baffled now Peter. I turned the set on to do some more of your checks and the hum is completely gone. I've turned the set upside down and rightside up several times during this testing and I wonder if a piece of solder or something was in there somewhere shorting something and it fell out. I'll keep looking for anything that might have been causing the noise. What do you think? Could something have been in there shorting and fell out?
Kirk
Sure junk caught in there like solder blobs etc can do it.
That's very possible.
But going back to the logic part... if the hum was gone in the phono position. that means it was being cause by something prior to the audio section...
That means it was coming from somewhere in the RF/IF area.
But it's all moot now...
Glad it's gone.
Now you can try out the Mp-3 thingie!
:Sure junk caught in there like solder blobs etc can do it.
:That's very possible.
:
:But going back to the logic part... if the hum was gone in the phono position. that means it was being cause by something prior to the audio section...
:That means it was coming from somewhere in the RF/IF area.
:
:But it's all moot now...
:Glad it's gone.
:
:Now you can try out the Mp-3 thingie!
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:Yes! Thanks Peter! I'll hook up the MP3 into the set wiring tomorrow and let you know how it works out.
Kirk
:Sure junk caught in there like solder blobs etc can do it.
:That's very possible.
:
:But going back to the logic part... if the hum was gone in the phono position. that means it was being cause by something prior to the audio section...
:That means it was coming from somewhere in the RF/IF area.
:
:But it's all moot now...
:Glad it's gone.
:
:Now you can try out the Mp-3 thingie!
:
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:I think it's gonna get frustrating now. Radio played great for hours last night. Turned it off, came out this morning and turned it on and the hum is back. Didn't touch the set at all. Just turned it on. So my problem is intermittent. What would I even look for now?
Kirk
::Sure junk caught in there like solder blobs etc can do it.
::That's very possible.
::
::But going back to the logic part... if the hum was gone in the phono position. that means it was being cause by something prior to the audio section...
::That means it was coming from somewhere in the RF/IF area.
::
::But it's all moot now...
::Glad it's gone.
::
::Now you can try out the Mp-3 thingie!
::
::
::
::I think it's gonna get frustrating now. Radio played great for hours last night. Turned it off, came out this morning and turned it on and the hum is back. Didn't touch the set at all. Just turned it on. So my problem is intermittent. What would I even look for now? Oh! I didn't try hooking the MP3 wires back up either. Just turned it on.
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:Kirk
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::Kirk
A cathode to heater short can certainly cause hum.
Wouldn't hurt to swap out some tubes carefully.
Otherwise do what I suggested yesterday... If the hum is not there in the phono position...
then start grounding the grids in each stage working backward toward the RF input stage.
:::Kirk
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:Sometimes an inter-electrode short in a tube can do that.
:A cathode to heater short can certainly cause hum.
:Wouldn't hurt to swap out some tubes carefully.
:
:Otherwise do what I suggested yesterday... If the hum is not there in the phono position...
:then start grounding the grids in each stage working backward toward the RF input stage.
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:Hi Peter & Kirk,
I've been monitoring the talk on this one. I've been having similar problems with a 12-S-370 I'm working on. In fact Peter in another forum you gave me instructions on the MP3 installation also. I think I just found my hum problem. Don't know if it will help Kirk out but I removed the AC line bypass .005 cap from my set and my hum is gone. I did try putting a new .005 cap in but the hum comes back. Guess I just won't have a line bypass cap.
While I'm here... My MP3 installation went well and it seems to work but the volume is extremely low. The MP3 player volume sounds good thru the headset that goes with it but it's just low thru the radio. Any idea what may cause this?
Thanks Peter! Hope you're not freezing your tail off like I am out west here. Low temps between 6 and 8 degrees past couple of days. None of that white stuff though. Had enough of that last year.
Johnny
:I've been monitoring the talk on this one. I've been having similar problems with a 12-S-370 I'm working on. In fact Peter in another forum you gave me instructions on the MP3 installation also. I think I just found my hum problem. Don't know if it will help Kirk out but I removed the AC line bypass .005 cap from my set and my hum is gone. I did try putting a new .005 cap in but the hum comes back. Guess I just won't have a line bypass cap.
:
:While I'm here... My MP3 installation went well and it seems to work but the volume is extremely low. The MP3 player volume sounds good thru the headset that goes with it but it's just low thru the radio. Any
idea what may cause this?
:
:Thanks Peter! Hope you're not freezing your tail off like I am out west here. Low temps between 6 and 8 degrees past couple of days. None of that white stuff though. Had enough of that last year.
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:Johnny
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Yeah...
It's getting so cold here.. they had to start chipping the dogs off the fire hydrants! lol
I don't know why c22 would contribute to hum.
Maybe Norm or Edd could chime in here with a few ideas about that.
As far as the Mp3 signal input sounding low...
What is the Mp3- vol output set to? Max?
there's a lot of tone controls components there where the phono input comes in and maybe some one particular tone setting may help improve it.
If all else fails maybe you might have to feed into the 1st audio grid via a cap.. and bypass the radio's vol control. Then you'd have only the MP3 volume to use. Not sure if that would be much better.. have to experiment.
How low is it?
::I've been monitoring the talk on this one. I've been having similar problems with a 12-S-370 I'm working on. In fact Peter in another forum you gave me instructions on the MP3 installation also. I think I just found my hum problem. Don't know if it will help Kirk out but I removed the AC line bypass .005 cap from my set and my hum is gone. I did try putting a new .005 cap in but the hum comes back. Guess I just won't have a line bypass cap.
::
::While I'm here... My MP3 installation went well and it seems to work but the volume is extremely low. The MP3 player volume sounds good thru the headset that goes with it but it's just low thru the radio. Any
:idea what may cause this?
::
::Thanks Peter! Hope you're not freezing your tail off like I am out west here. Low temps between 6 and 8 degrees past couple of days. None of that white stuff though. Had enough of that last year.
::
::Johnny
::
:
:Hi johnny;
:Yeah...
:It's getting so cold here.. they had to start chipping the dogs off the fire hydrants! lol
:
:I don't know why c22 would contribute to hum.
:
:Maybe Norm or Edd could chime in here with a few ideas about that.
:
:As far as the Mp3 signal input sounding low...
:What is the Mp3- vol output set to? Max?
:
:there's a lot of tone controls components there where the phono input comes in and maybe some one particular tone setting may help improve it.
:
:If all else fails maybe you might have to feed into the 1st audio grid via a cap.. and bypass the radio's vol control. Then you'd have only the MP3 volume to use. Not sure if that would be much better.. have to experiment.
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:How low is it?
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:Chip the dogs off the fire hydrants... GI you funny. My wife got a kick outa that one. I fixed the low volume problem on the MP3 by actually putting some solder on the connection to the wire that goes to the phono jack. What a difference this new solder stuff makes.lol
I guess that .005 bypass cap on the AC line is to get rid of any line noise. What ever it does it was making the hum worse. I'm running it without any cap now and the set sounds fine. Now I gotta figure out how to make the preset station switches work. I'm dealing with that over at ARF. Thanks for the help on the MP3 thing.
Johnny
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:I guess that .005 bypass cap on the AC line is to get rid of any line noise. What ever it does it was making the hum worse. I'm running it without any cap now and the set sounds fine. Now I gotta figure out how to make the preset station switches work. I'm dealing with that over at ARF. Thanks for the help on the MP3 thing.
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:Johnny
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Wow.. solder! huh? You hve to heat that stuff too.
I call it "electronic glue"
I know of a guy in our radio club back in the 60s who put a whole Heathkit receiver together and wondered why it didn't work.
So he brought it into the club so we could look at it and try to help figure out what was wrong.
Holy Cow... lol
... he soldered every joint... yeah ...but what a mess.. BECAUSE he never stripped the insulation off the wires !!!
He said nobody told him about that part... lol
:::Kirk
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:Sometimes an inter-electrode short in a tube can do that.
:A cathode to heater short can certainly cause hum.
:Wouldn't hurt to swap out some tubes carefully.
:
:Otherwise do what I suggested yesterday... If the hum is not there in the phono position...
:then start grounding the grids in each stage working backward toward the RF input stage.
:
:
:Changing that capacitor didn't make any difference on this set. I did however order a new 6L7 tube because it's the only one I haven't tried replacing. That came in yesterday and so far it seems to have fixed my problem. Now I'll concentrate on the MP3 part.
Kirk
Is there any chance that it is coming from your home wiring. Do you have a fan on or a light dimmer switch in operation?
Jeff
:::I think it's gonna get frustrating now. Radio played great for hours last night. Turned it off, came out this morning and turned it on and the hum is back. Didn't touch the set at all. Just turned it on. So my problem is intermittent. What would I even look for now? Oh! I didn't try hooking the MP3 wires back up either. Just turned it on.
::::Kirk
::
::Sometimes an inter-electrode short in a tube can do that.
::A cathode to heater short can certainly cause hum.
::Wouldn't hurt to swap out some tubes carefully.
::
::Otherwise do what I suggested yesterday... If the hum is not there in the phono position...
::then start grounding the grids in each stage working backward toward the RF input stage.
::
::
::Changing that capacitor didn't make any difference on this set. I did however order a new 6L7 tube because it's the only one I haven't tried replacing. That came in yesterday and so far it seems to have fixed my problem. Now I'll concentrate on the MP3 part.
:Kirk
: