Hello everyone this past weekend I picked up at one of my favorite antique shops near me a 1935 GE Model A-53 AM/SW tombstone radio that needed some work done to it (it was missing the power cord, had a blown out flexible Resistor R-11 a 450 ohm 1W Flexible Resistor, some bad capacitors a bad tube and an incorrect rectifier tube).

I've got the radio completely recapped but dummy me forgot to order a replacement resistor for the blown out Flexible Resistor, which I would assume a 470 Ohm 1 Watt Flameproof resistor would work in place of the old flexible resistor?

Thanks for your help.

Hello everyone this past weekend I picked up at one of my favorite antique shops near me a 1935 GE Model A-53 AM/SW tombstone radio that needed some work done to it (it was missing the power cord, had a blown out flexible Resistor R-11 a 450 ohm 1W Flexible Resistor, some bad capacitors a bad tube and an incorrect rectifier tube).

I've got the radio completely recapped but dummy me forgot to order a replacement resistor for the blown out Flexible Resistor, which I would assume a 470 Ohm 1 Watt Flameproof resistor would work in place of the old flexible resistor?

Thanks for your help.
I can't see why a 470 ohm, 1w resistor wouldn't work. It's in the cathode circuit, of the audio output circuit. The rectifier tube can be a 5Y3, 5W4 or another 5Z4.
I have one just like it! It's a strange non-AVC superhet, with the volume control that isn't in the detector circuit.

I can't see why a 470 ohm, 1w resistor wouldn't work. It's in the cathode circuit, of the audio output circuit. The rectifier tube can be a 5Y3, 5W4 or another 5Z4.
I have one just like it! It's a strange non-AVC superhet, with the volume control that isn't in the detector circuit.

Well, this one had a 5U4GB in it in place of the 5Z4 Rectifier tube, and all of the tube substitution books I have show that the 5Y3 and the 5W4 are not substitutes for the 5Z4 tube, and neither is the 5U4.

Is it common for those old flexible resistors to just blow apart? I'm asking because this resistor's outer cloth shell was completely disintigrated and all that was left was the resistor's wire element which then shorted to the chassis and left a burn mark on the chassis where it shorted to the chassis! :thumbsdn: :smoke:

Also as for the replacement resistor I did come across in my parts stash 2 270 Ohm 2 watt flameproof resistors that I tied together in series to make a 540 Ohm 2 watt resistor (the original resistor had no tolerance markings listed so I figured that that would be close enough.

the original 6A8 tube (this radio had all metal cased tubes which were brand new at that time) was completely dead according to my tube testers (I tested it on my Knight Model 600 Tube Tester, my Sencore Mighty Mite VII Tube Tester and on a B & K Model 606/666 Tube Tester and all three of them tested the tube as bad/zero emissions), thankfully I had a NOS 6A8GT tube that I was able to stick in there, hopefully it won't affect the performance of the radio with it not being a metal cased tube like the rest of the tubes.

You said this radio doesn't have AVC or a standard Volume Control configuration, how does this radio perform compared to others in your opinion? I like to use these radios for Night Time DX'ing.

Well, this one had a 5U4GB in it in place of the 5Z4 Rectifier tube, and all of the tube substitution books I have show that the 5Y3 and the 5W4 are not substitutes for the 5Z4 tube, and neither is the 5U4.

Is it common for those old flexible resistors to just blow apart? I'm asking because this resistor's outer cloth shell was completely disintigrated and all that was left was the resistor's wire element which then shorted to the chassis and left a burn mark on the chassis where it shorted to the chassis! :thumbsdn: :smoke:

Also as for the replacement resistor I did come across in my parts stash 2 270 Ohm 2 watt flameproof resistors that I tied together in series to make a 540 Ohm 2 watt resistor (the original resistor had no tolerance markings listed so I figured that that would be close enough.

the original 6A8 tube (this radio had all metal cased tubes which were brand new at that time) was completely dead according to my tube testers (I tested it on my Knight Model 600 Tube Tester, my Sencore Mighty Mite VII Tube Tester and on a B & K Model 606/666 Tube Tester and all three of them tested the tube as bad/zero emissions), thankfully I had a NOS 6A8GT tube that I was able to stick in there, hopefully it won't affect the performance of the radio with it not being a metal cased tube like the rest of the tubes.

You said this radio doesn't have AVC or a standard Volume Control configuration, how does this radio perform compared to others in your opinion? I like to use these radios for Night Time DX'ing.
The 5Z4 is a real odd-ball tube! The first ones looked like a ballast tube, with a perforated metal housing and two sealed capsules in it. They only made it for a short time, as they were failure prone. The newer 5Z4's were like a metal 6F6. As I stated, the 5Y3 has a 5volt 2amp heater and the same pin-out. The 5U4 has a 3amp heater and too much current for the power transformer.
Regarding the flexible resistor, they all crumbled after so many years. I would use two resistors to equal a value closer to 450-470 ohms.
When DXing with a TRF or a non-AVC superhet, you have to have the volume control set to max, to have the sensitivity to seek out distant stations.
If the radio squeals or motorboats, you might have to use a tube shield on the 6A8GT.

The 5Z4 is a real odd-ball tube! The first ones looked like a ballast tube, with a perforated metal housing and two sealed capsules in it. They only made it for a short time, as they were failure prone. The newer 5Z4's were like a metal 6F6. As I stated, the 5Y3 has a 5volt 2amp heater and the same pin-out. The 5U4 has a 3amp heater and too much current for the power transformer.
Regarding the flexible resistor, they all crumbled after so many years. I would use two resistors to equal a value closer to 450-470 ohms.
When DXing with a TRF or a non-AVC superhet, you have to have the volume control set to max, to have the sensitivity to seek out distant stations.
If the radio squeals or motorboats, you might have to use a tube shield on the 6A8GT.

Well it seems that this radio may not work with an unshielded 6A8 tube in the set as the radio just hums/motorboats really badly when fed a signal from my signal generator or any other kind of signal and unfortunately I don't have any tube shields that are large enough in diameter to fit over an octal tube and short enough to go over a 6A8GT tube so that the gridcap can go over it... :sigh:

when I have the original 6A8 metal tube in the radio it doesn't do anything (no audio or anything) but then when I turn off the radio I can hear my signal generator coming through loud and clear and undistorted (no hum/motorboating), which tells me that they wired this radio up so that it could only use metal cased tubes I think... :scratch2:

As for the resistors, I already have the 2 270 ohm 2 watt reistors installed in the radio, and I don't really want to have to go back in and remove it and reinstall new ones again as it was a pain in the butt to install them the first time around, is there any sort of problem with having a resistor that's 70 ohms higher than the original? The original resistor as I said previously didn't have any sort of tolerance listing listed for it in the Rider's Service Data which usually means its at least 20% tolerance or more, and 20% of 470 is 94 ohms which means that 540 Ohms is well within the original specs... :scratch2: :thmbsp:

If your crafty you can make a temporary shield out of aluminum foil to use till you can find an appropriate original...

I was able to jury rig a tall octal tube shield by cutting it down so that it was the appropriate height and it still seems to be having issues with motorboating when a signal is applied to it with my signal generator, it basically just hums like mad when a signal is fed through the radio, either through the grid of the 6A8 tube or through the antenna wires, and the hum goes away when you tune away from the signal, and also the hum gets louder or softer depending on how you adjust the gridcaps on the 6K7 and 6J7 tubes, any ideas as to what might be going on here?

I was able to jury rig a tall octal tube shield by cutting it down so that it was the appropriate height and it still seems to be having issues with motorboating when a signal is applied to it with my signal generator, it basically just hums like mad when a signal is fed through the radio, either through the grid of the 6A8 tube or through the antenna wires, and the hum goes away when you tune away from the signal, and also the hum gets louder or softer depending on how you adjust the gridcaps on the 6K7 and 6J7 tubes, any ideas as to what might be going on here?
Did you ground the tube shield with as short of a wire as possible?
Also, was any component drastically relocated in the convertor or IF circuit?
The servicing instructions state that the set could be unstable under certain conditions.
Maybe you have to wait until you can obtain a metal 6A8. :sigh:

Well it seems that this radio may not work with an unshielded 6A8 tube in the set as the radio just hums/motorboats really badly when fed a signal from my signal generator or any other kind of signal and unfortunately I don't have any tube shields that are large enough in diameter to fit over an octal tube and short enough to go over a 6A8GT tube so that the gridcap can go over it... :sigh:

when I have the original 6A8 metal tube in the radio it doesn't do anything (no audio or anything) but then when I turn off the radio I can hear my signal generator coming through loud and clear and undistorted (no hum/motorboating), which tells me that they wired this radio up so that it could only use metal cased tubes I think... :scratch2:

As for the resistors, I already have the 2 270 ohm 2 watt reistors installed in the radio, and I don't really want to have to go back in and remove it and reinstall new ones again as it was a pain in the butt to install them the first time around, is there any sort of problem with having a resistor that's 70 ohms higher than the original? The original resistor as I said previously didn't have any sort of tolerance listing listed for it in the Rider's Service Data which usually means its at least 20% tolerance or more, and 20% of 470 is 94 ohms which means that 540 Ohms is well within the original specs... :scratch2: :thmbsp:
That statement usually pertains to carbon resistors! Wire wounds are usually pretty close. The flexible ones are wire wound. :scratch2:

Sounds like there might be a 'floating grid' condition with the 6A8. That's when the DC path to the control grid is open (like an open in the RF coil or bandswitch). What resistance do you measure from the grid cap to ground?

(Since there's no AVC bus, the coil ties directly to ground according to the schematic.)

That statement usually pertains to carbon resistors! Wire wounds are usually pretty close. The flexible ones are wire wound. :scratch2:

I have since removed the series 270 Ohm 2 Watt resistors and replaced it with a 270 ohm 2 watt and a 180 ohm 2 watt resistor in series to make a 450 Ohm 2 Watt resistor.

Did you ground the tube shield with as short of a wire as possible?
Also, was any component drastically relocated in the convertor or IF circuit?
The servicing instructions state that the set could be unstable under certain conditions.
Maybe you have to wait until you can obtain a metal 6A8. :sigh:

The only "alterations" I made to the IF and converter circuit was replacing the grid cap wire leads for the 6A8 tube and the 6K7 tube because the wire leads for the wire leads were dry rotted and had exposed wire.

Other than that when I replaced old capacitors and resistors I put them back where they were originally in the circuit (I completely unsoldered each capacitor from their respective tie points and soldered the new capacitors back in where the old ones connected originally).

The only components I relocated were the two 8 MFD electrolytic can caps that were bad (the ones on top of the chassis), I disconnected the components from the old capacitor leads, and then took a terminal strip with a blank mounting tab (mounting tab with no terminal attached) and soldered it to the terminal on the old can cap that way the components and the new capacitor was isolated from the old cap but was mounted in a convenient spot.

I reattached the wires/components and the new capacitors to one of the isolated terminals on the newly attached terminal strip and attached the negative lead of the new capacitor to the chassis just like the old ones were, and I made sure that the leads from the new capacitors were as short as possible.

The only other thing I can think of is that maybe when I installed the new wire leads for the grid caps on the 6A8 and 6K7 tubes I might of made the leads too long, but it was kind of hard to know how much lead to use especially on the 6K8 tube's grid cap lead because I had to go from under the IF can to the top of the 6K8 tube which is about 2 inches, and I think I may have cut about 3 inches of wire lead because I wasn't sure how much I needed for sure and I didn't want to cut myself too short.

Could having too long of grid cap wire leads cause the issues I'm having?

Sounds like there might be a 'floating grid' condition with the 6A8. That's when the DC path to the control grid is open (like an open in the RF coil or bandswitch). What resistance do you measure from the grid cap to ground?

(Since there's no AVC bus, the coil ties directly to ground according to the schematic.)

Its 5.5 Ohms from the 6A8 Grid Cap to chassis ground.

Is that what its supposed to measure, or do I have the aforementioned "floating grid" issue you spoke of?

I have since removed the series 270 Ohm 2 Watt resistors and replaced it with a 270 ohm 2 watt and a 180 ohm 2 watt resistor in series to make a 450 Ohm 2 Watt resistor.
In a self-biased output tube circuit, it's best to be close to the original cathode bias resistor. It'll save a distortion issue, later on!
You seem to get some, not-to-common sets to repair, restore! :scratch2:

Its 5.5 Ohms from the 6A8 Grid Cap to chassis ground.

Is that what its supposed to measure, or do I have the aforementioned "floating grid" issue you spoke of?

It's definitely not floating. A few (or several) ohms sounds right. Floating would be infinite resistance.

Well I figured out what my problem was, my one replacement filter cap that I installed to replace one of the old can caps on top of the chassis didn't have a good solid ground connection to the chassis, so I unsoldered the negative lead from where I had soldered it to the chassis, roughed up the metal chassis in the area where the negative capacitor lead was to go and then resoldered the negative lead to the chassis (that solved the incessant humming noise issue)

and the issue with the extremely distorted audio when being fed a signal from the RF Signal Generator, was because the grid cap for the 6J7 was grounding itself out (the grid cap wire lead had apparently lost enough of its rubber insulation inside the shielding sleeve that the shielding sleeve was causing the grid cap wire to ground out against the shielding sleeve, so I took and replaced the grid cap wire lead and BAM! the radio started working properly!

The only problem I have now is that the volume control seems to have some "dead spots" in it because it will go from completely silent to blow your ears out in a quarter turn and then I think the speaker might have some issues because the audio comes out completely distorted and barely audible at about quarter volume or a little less, and when you turn it up to about half way the sound is so distorted that you can barely hear what is being said on the radio.

Just thought I would give a little update on this radio.

OK So another update:

I DID have this radio working fine last night, but then when I went to install a permanent power cord onto it tonight (instead of the temporary one I had on last night for testing purposes) I went to fire the radio up after installing the new permanent power cord and wouldn't you know it the radio went back to humming like a son of a gun again! :sigh: :thumbsdn:

I checked all of the ground connections and they were fine, I checked all of the electrolytics and they were fine, and I even checked the 6J7 tube's Grid Cap wire shielding and that was fine so I don't know what to say about this thing! :no:

Any ideas as to what to check next? Because I'm starting to run fresh out of ideas on this thing...

Well I figured out what my problem was, my one replacement filter cap that I installed to replace one of the old can caps on top of the chassis didn't have a good solid ground connection to the chassis, so I unsoldered the negative lead from where I had soldered it to the chassis, roughed up the metal chassis in the area where the negative capacitor lead was to go and then resoldered the negative lead to the chassis (that solved the incessant humming noise issue)

and the issue with the extremely distorted audio when being fed a signal from the RF Signal Generator, was because the grid cap for the 6J7 was grounding itself out (the grid cap wire lead had apparently lost enough of its rubber insulation inside the shielding sleeve that the shielding sleeve was causing the grid cap wire to ground out against the shielding sleeve, so I took and replaced the grid cap wire lead and BAM! the radio started working properly!

The only problem I have now is that the volume control seems to have some "dead spots" in it because it will go from completely silent to blow your ears out in a quarter turn and then I think the speaker might have some issues because the audio comes out completely distorted and barely audible at about quarter volume or a little less, and when you turn it up to about half way the sound is so distorted that you can barely hear what is being said on the radio.

Just thought I would give a little update on this radio.

You probably have to remove the volume control and have a look inside!
IDK if the volume control is a log or a linear taper. Also, the schematic shows a 250ohm resistor in series, but the parts list shows that the resistor is part of the control. Some experimenting is needed!
Re: the next entry problem with the hum, maybe the 6J7 or the 6F6 has an H-K short.
Sure is one for the books.

I cannot for the life of me imagine how just changing the power cord would cause a very loud 60-Hz hum as you are describing; after all, the power cord itself should not have any effect whatsoever on the audio output. If the radio had been working up to now, the only thing I can come up with is a heater-cathode short in one of the audio tubes. Given this radio is very old (pre-WWII vintage), that would not surprise me in the least. Vibration from moving the chassis could have caused such a short, especially if the tube were about to develop an H/K short eventually.

I would not operate the radio in its present condition if it does not have an AC line fuse (it is my understanding that most pre-war radios did not have such a fuse, which all too often led to very serious trouble if a tube were to develop an H/K short or a filter cap would short the same way). The house fuse might blow in case of a shorted tube or filter capacitor, but I wouldn't count on it.

You probably have to remove the volume control and have a look inside!
IDK if the volume control is a log or a linear taper. Also, the schematic shows a 250ohm resistor in series, but the parts list shows that the resistor is part of the control. Some experimenting is needed!
Re: the next entry problem with the hum, maybe the 6J7 or the 6F6 has an H-K short.
Sure is one for the books.

Well for sure I did swap out the 6F6 tube and the 6J7 tubes for known good tubes to check the H-K Short theory and of course it still has that nasty hum to it even after swapping in known good tubes.

I ohmed out the volume control pot just to make sure it was still good and it was only measuring 1 ohm all across the pot no matter where the volume control knob was set, which tells me that the volume control pot has failed and is perhaps what is causing my humming problem, because the volume control is grounded to chassis using the left side terminal and goes to the kathode of the 6A8 tube from the middle and right side tap of the volume control pot.

Is there any way to test this theory by somehow taking the volume control pot out of the circuit?

I cannot for the life of me imagine how just changing the power cord would cause a very loud 60-Hz hum as you are describing; after all, the power cord itself should not have any effect whatsoever on the audio output. If the radio had been working up to now, the only thing I can come up with is a heater-cathode short in one of the audio tubes. Given this radio is very old (pre-WWII vintage), that would not surprise me in the least. Vibration from moving the chassis could have caused such a short, especially if the tube were about to develop an H/K short eventually.

I would not operate the radio in its present condition if it does not have an AC line fuse (it is my understanding that most pre-war radios did not have such a fuse, which all too often led to very serious trouble if a tube were to develop an H/K short or a filter cap would short the same way). The house fuse might blow in case of a shorted tube or filter capacitor, but I wouldn't count on it.


I think I figured out what happened, I think the volume control pot is what's causing the radio to hum, because I think the volume control pot (which was already sketchy when I had gotten the radio going) finally went to "pots" (pun intended) when I attempted to clean the volume control pot with contact cleaner to see if I could restore the volume control's functionality again (because as I had mentioned before the volume control pot when it was working before it apparently finally failed would cut in and out depending on where the volume contol was rotated.)

Does any one on here have any known working volume controls with a built in power switch that they could send me?

I think I figured out what happened, I think the volume control pot is what's causing the radio to hum, because I think the volume control pot (which was already sketchy when I had gotten the radio going) finally went to "pots" (pun intended) when I attempted to clean the volume control pot with contact cleaner to see if I could restore the volume control's functionality again (because as I had mentioned before the volume control pot when it was working before it apparently finally failed would cut in and out depending on where the volume contol was rotated.)

Does any one on here have any known working volume controls with a built in power switch that they could send me?
I don't think there's too many volume controls of that value around! :sigh:
Check it with all the leads disconnected and see if it reads the same.
Remove it from the chassis and look inside.
All kinds of strange goings on with that set.

I don't think there's too many volume controls of that value around! :sigh:
Check it with all the leads disconnected and see if it reads the same.
Remove it from the chassis and look inside.
All kinds of strange goings on with that set.

OK Will do.

OK Will do.

I've seen non-AVC superhet radio circuits, but that one is a real gem.
I repaired the one I have or had, but I just replaced the bad caps and never realized that the set was that strange! :thumbsdn:

OK Will do.

I located that chassis in my collection. I'm not sure if I have the cabinet, so I don't want to part it out.
It sure is a strange beast!

I located that chassis in my collection. I'm not sure if I have the cabinet, so I don't want to part it out.
It sure is a strange beast!

how is yours wired up?

how is yours wired up?

I think the same, but I'll look again to look at the connection. :scratch2:

I think the same, but I'll look again to look at the connection. :scratch2:

Here's a picture of the underside of my radio, is there anything that looks out of place here compared to yours?

I had a look at the schematic and the 5000 ohm volume control seems to vary suppressor grid voltage on the 6K7 IF tube.

Here's a picture of the underside of my radio, is there anything that looks out of place here compared to yours?
That volume control pot looks like a replacement and a wire-wound control.
The one in my chassis is smaller, possibly the original.

I had a look at the schematic and the 5000 ohm volume control seems to vary suppressor grid voltage on the 6K7 IF tube.
Looks like it also ties to the cathode and to the 6A8 cathode. So applying varying positive voltage on the cathodes equates to varying neg. voltage on G1s (control grids).

Well I'm not sure about the volume control and whether or not its original or not because its the same exact volume control pot as what's in my Philco 116B which is from 1936 and unfortunately it has developed the same "sticking" power switch issue as the power switch on my Philco 116B has.

The volume control/power switch pot on this radio is a CTS (Central Telephone System) Type T Power Switch/Volume Control Pot, which seems seems to be a trouble proned volume control/power switch pot, because actually come to think of it this humming issue is exactly what my Philco 116B did which I thought it was bad filter caps but now thinking upon it I'm now wondering if it wasn't maybe a bad volume control pot, which I'm now wondering if that's not the case here...

CTS by the way has a plant in Elkhart, Indiana which is not too far from where I live, which is actually where the two aforementioned pots were made.

I had acquired late last year, more or less the sister set to this radio the RCA 5T and that thing when I first acquired, would blow the breaker for the circuit my workshop was on in my house, (and he told me that's all it did for him as well, and that was why he was selling it).

It was because the previous owner of the set a fellow antique radio enthusiast/collector had at one point replaced the original cloth cord with a modern lamp cord but he didn't wire it up right, which was why it was blowing the breaker, and it took me a few months of studying the Rider's Manual and the old RCA Red Book service diagrams for this radio to figure out that the wiring diagrams for the switch on this radio on those manuals (or at least the Rider's anyways) were written incorrectly and had the "dummy terminal" on the Power Switch marked in the wrong spot which is I think why the previous owner had issues with the wiring of the RCA 5T I am currently writting about.

Anyways the RCA 5T I just got going is a great performing set, its super sensitive and selective and the SW band on it picks up stations like its nobody's business (I was picking up the WWVB time stamp signal @ 5 MHz, I was picking up many Religious Stations on the SW band, and I was even picking up Radio Havanna out of Havanna, Cuba on it!

Anyways my point is that some of these old radios are super easy to repair and troubleshoot and some of these radios are a pain to troubleshoot even using the best troubleshooting skills one has to offer.

Actually calling the RCA 5T the "sister radio" to the GE A-53 is kind of inaccurate because the 5T is a vastly superior radio to the GE A-53 in many ways including the fact that the 5T has a great performing AVC circuit, whereas the GE A-53 lacks any sort of proper AVC circuit.

A little update:

I think I may have found a replacement switch/volume control that might work on this radio, someone gave me an old junker Philco Model 60 Cathedral Radio from the same time period as this GE is from (1936) and it also had a CTS Model T power switch/volume control assembly in it, the volume control pot on this switch/volume control is a 500k Ohm (.5 Meg) pot and I was wondering if this might be a viable replacement (even though this radio's original pot was 5k ohms) would the 500k vs. 5k make that much of a difference in how this radio performs?

Any help in this matter would be appreciated.

Thanks.

Well Unfortunately I think the radio's power transformer got fried because when I tried turning it on the pilot light wouldn't light up (the bulb is still good), and the power transformer was really hot to the touch and the Kill-a-watt meter was reading over 100 watts and the rectifier tube was the only tube that was hot to the touch, the rest of the tubes were stone cold.

So I think this radio unfortunately might be toast. :sigh:

A little update:

I think I may have found a replacement switch/volume control that might work on this radio, someone gave me an old junker Philco Model 60 Cathedral Radio from the same time period as this GE is from (1936) and it also had a CTS Model T power switch/volume control assembly in it, the volume control pot on this switch/volume control is a 500k Ohm (.5 Meg) pot and I was wondering if this might be a viable replacement (even though this radio's original pot was 5k ohms) would the 500k vs. 5k make that much of a difference in how this radio performs?

Any help in this matter would be appreciated.

Thanks.
The 500K pot is strictly an audio pot. It won't control the bias on those tubes.

Well Unfortunately I think the radio's power transformer got fried because when I tried turning it on the pilot light wouldn't light up (the bulb is still good), and the power transformer was really hot to the touch and the Kill-a-watt meter was reading over 100 watts and the rectifier tube was the only tube that was hot to the touch, the rest of the tubes were stone cold.

So I think this radio unfortunately might be toast. :sigh:
When testing a radio transformer, always remove the rectifier tube first before applying power, in case the set has a B+ short, electrolytic or other component.
Either the PT is wasted or the short was robbing the 6V heater circuit.
Try it again with the watt-watcher and the 80 tube removed.

...when I tried turning it on the pilot light wouldn't light up (the bulb is still good), and the power transformer was really hot to the touch....
How long was it run in that condition?

When testing a radio transformer, always remove the rectifier tube first before applying power, in case the set has a B+ short, electrolytic or other component.
Either the PT is wasted or the short was robbing the 6V heater circuit.
Try it again with the watt-watcher and the 80 tube removed.

It actually has a 5Z4 rectifier tube in it, but either way, I removed that tube from the radio, plugged it in turned it on, and sure enough I heard a well pronounced sizzling noise coming from the transformer, so yes I definitely think the transformer is bad. :sigh:

I have a power transformer on the Philco 60 that I could check to see if its still good or not, and if it is I might be able to swap that into this radio, because the Philco 60 is a very similar chassis design to this GE (2 band radio, AM and SW, similar tube count as well, and same tube voltages).

The the radio wasn't on that way very long, I turned it off right away as soon as I saw it wasn't working and felt that the transformer was getting hot.

what do you guys think?

It actually has a 5Z4 rectifier tube in it, but either way, I removed that tube from the radio, plugged it in turned it on, and sure enough I heard a well pronounced sizzling noise coming from the transformer, so yes I definitely think the transformer is bad. :sigh:

I have a power transformer on the Philco 60 that I could check to see if its still good or not, and if it is I might be able to swap that into this radio, because the Philco 60 is a very similar chassis design to this GE (2 band radio, AM and SW, similar tube count as well, and same tube voltages).

The the radio wasn't on that way very long, I turned it off right away as soon as I saw it wasn't working and felt that the transformer was getting hot.

what do you guys think?
I got lost in the dialogue!
What transformer is damaged? The one in the GE A83 or the one in the Philco?

I got lost in the dialogue!
What transformer is damaged? The one in the GE A83 or the one in the Philco?

The transformer in the GE is bad, and I want to see if the transformer in the Philco will be a suitable replacement or not.

The transformer in the GE is bad, and I want to see if the transformer in the Philco will be a suitable replacement or not.
I checked the schematic and the power transformer looks close!
The B+ might be a little high!
Tag the leads when disconnecting from the original chassis, as the Philco colors might be different.

I checked the schematic and the power transformer looks close!
The B+ might be a little high!
Tag the leads when disconnecting from the original chassis, as the Philco colors might be different.

I'm also concerned about the fact that the Philco uses the old style tubes vs. the GE using the Octal style tubes, would that make a difference?

I'm also concerned about the fact that the Philco uses the old style tubes vs. the GE using the Octal style tubes, would that make a difference?

The tubes are identical, except the base. Same heater current and voltage.
Philco didn't switch to octal base tubes until the '37 model year. :thumbsdn:

The tubes are identical, except the base. Same heater current and voltage.
Philco didn't switch to octal base tubes until the '37 model year. :thumbsdn:

OK, so then the power transformer should be able to swap out for each other, the only other issue I could see being a problem is the mounting screw hole spacing for the power transformer from the Philco radio vs. the the GE's original Power Transformer.

OK, so then the power transformer should be able to swap out for each other, the only other issue I could see being a problem is the mounting screw hole spacing for the power transformer from the Philco radio vs. the the GE's original Power Transformer.

You might have to drill different holes to match the footprint of the replacement transformer. The original transformer is mounted a little different, with long through bolts, so it sits above the chassis.

You might have to drill different holes to match the footprint of the replacement transformer. The original transformer is mounted a little different, with long through bolts, so it sits above the chassis.

Well a little update, apparently the power transformer wasn't the problem, it was the power switch on the volume control I subbed in, apparently the power switch was bad...? because I put the original volume control and power switch back into the radio last night and the radio popped right on as soon as I powered it on... Weird, I didn't know those power switches could go bad like that.

Unfortunately that persistant and untraceable hum is still there and I still cannot figure out where its coming from.

Well for sure something's not right with this radio because the back of the radio says it's rated for 65 watts at 120 and the radio as it sits with its incessant 60 Hz hum is only 43 Watts so something's not right, either one of my filter caps failed or there's a bad tube or something else odd is going on with this radio.

I've tested all of the tubes in this radio and the 6K7 tube and the 6F6 tube both tested as having a H-K Short in it so I subbed them out with known good tubes and the hum is still there and the radio pulled the same amount of wattage, So I'm not sure what's going on with this mystery of a radio.

I'm about tempted to just salvage the bulb and tubes and capacitors out of the radio and scrap it out.

Well for sure something's not right with this radio because the back of the radio says it's rated for 65 watts at 120 and the radio as it sits with its incessant 60 Hz hum is only 43 Watts so something's not right, either one of my filter caps failed or there's a bad tube or something else odd is going on with this radio.

I've tested all of the tubes in this radio and the 6K7 tube and the 6F6 tube both tested as having a H-K Short in it so I subbed them out with known good tubes and the hum is still there and the radio pulled the same amount of wattage, So I'm not sure what's going on with this mystery of a radio.

I'm about tempted to just salvage the bulb and tubes and capacitors out of the radio and scrap it out.
It depends what condition the cabinet is in! If the cabinet is in good condition, it's worth trouble-shooting a little further!
Remove all the tubes but the 6F6 and the rectifier and see if it still hums, proving it's a power supply issue. If so, bridge the electrolytics and see if it clears the hum. The power supply is a rather simple supply using a grounded B minus.

It depends what condition the cabinet is in! If the cabinet is in good condition, it's worth trouble-shooting a little further!
Remove all the tubes but the 6F6 and the rectifier and see if it still hums, proving it's a power supply issue. If so, bridge the electrolytics and see if it clears the hum. The power supply is a rather simple supply using a grounded B minus.

The Cabinet is actually in pretty decent shape yet, but I did try what you suggested last night before I even saw that you suggested it, and it still has a hum, actually the hum got worse when all but the 6F6 and the 5Z4 were removed from the chassis.

I didn't try bridging the electrolytics yet, but I'm not sure what you mean by that, do you want me to bridge all of the ground connections from the electrolytics?
If so I'm not sure how I would go about doing that seeing as all of them are grounded to the chassis in some way, shape, or form so they should technically already be bridged, seeing as the chassis is the common ground in this case.

Bridging simply means "connect in parallel with", using a pair of clip leads. So bridge (jumper) each individual electrolytic (one at a time) with a single unit of equivalent or higher ratings. Note correct polarity.

The caps in question would be C19 and C20 (main power supply filters). You could jumper each with something like a 20mf 450V unit and see if it affects the hum.

EDIT. Those two caps should be replaced as a matter of course anyway. If they're the original cans they could be left in place for aesthetics, but out of circuit. There's also C26, a low voltage electrolytic across the cathode resistor of the 6F6. It won't cause a hum problem, but will cause reduced volume if it's gone open. It should be replaced anyway.

Bridging simply means "connect in parallel with", using a pair of clip leads. So bridge (jumper) each individual electrolytic (one at a time) with a single unit of equivalent or higher ratings. Note correct polarity.

The caps in question would be C19 and C20 (main power supply filters). You could jumper each with something like a 20mf 450V unit and see if it affects the hum.

EDIT. Those two caps should be replaced as a matter of course anyway. If they're the original cans they could be left in place for aesthetics, but out of circuit. There's also C26, a low voltage electrolytic across the cathode resistor of the 6F6. It won't cause a hum problem, but will cause reduced volume if it's gone open. It should be replaced anyway.

Its already been done, none of the electrolytics in the radio are original to the set, that was the first thing I did when I got this set, was replace the old electrolytics, which I left the old cans in place for aesthetics and wired in some new electrolytics which I installed onto some isolated terminal strips that I soldered ontop of the old electrolytic can's positive terminal (the terminal strip's attachment lug was isolated from the terminals so the original cans are still out of the circuit but are being used as an attachment point for the terminal strip for the new electrolytics without affecting the circuit, its a trick I learned from Mr. Carlson's Lab.)

I checked the capacitors that I installed in the radio and they still test good yet on my ESR Meter, (they mesured about 4-6 ohms ESR and they both are 2 4.7 MFD 450V axial lead electrolytics paralleled together to make 10 MFD at 450V).

And then the low voltage electrolytic is a 10/10 @ 160V Firecracker type electrolytic cap like the original was, and that one tests fine as well.

So unless one of these caps failed in a manner I'm not aware of, or that the ESR meter wasn't able to detect (dead shorted) then I don't think the electrolytics are to blame here.

Its already been done, none of the electrolytics in the radio are original to the set, that was the first thing I did when I got this set, was replace the old electrolytics, which I left the old cans in place for aesthetics and wired in some new electrolytics which I installed onto some isolated terminal strips that I soldered ontop of the old electrolytic can's positive terminal (the terminal strip's attachment lug was isolated from the terminals so the original cans are still out of the circuit but are being used as an attachment point for the terminal strip for the new electrolytics without affecting the circuit, its a trick I learned from Mr. Carlson's Lab.)

I checked the capacitors that I installed in the radio and they still test good yet on my ESR Meter, (they mesured about 4-6 ohms ESR and they both are 2 4.7 MFD 450V axial lead electrolytics paralleled together to make 10 MFD at 450V).

And then the low voltage electrolytic is a 10/10 @ 160V Firecracker type electrolytic cap like the original was, and that one tests fine as well.

So unless one of these caps failed in a manner I'm not aware of, or that the ESR meter wasn't able to detect (dead shorted) then I don't think the electrolytics are to blame here.
Remove the rectifier tube and check the HV windings on pins 4&6. Should be around 600 volts AC or 300 volts from either 4 or 6 to ground. If it seems to be in order, replace the 5Z4 with a 5Y3. Maybe the 5Z4 got damaged!
I would leave the 5Y3 in there! I don't trust the old-time metal rectifiers!

Its already been done, none of the electrolytics in the radio are original to the set, that was the first thing I did when I got this set, was replace the old electrolytics, which I left the old cans in place for aesthetics and wired in some new electrolytics which I installed onto some isolated terminal strips that I soldered ontop of the old electrolytic can's positive terminal (the terminal strip's attachment lug was isolated from the terminals so the original cans are still out of the circuit but are being used as an attachment point for the terminal strip for the new electrolytics without affecting the circuit, its a trick I learned from Mr. Carlson's Lab.)

.

If the negative of the can is grounded you could alternately solder the terminal strip to the chassis so the mount lug of the strip can be used for a negative terminal...you need a powerful iron to do it that way but it can clean things up a bit in some cases.

With an ohmmeter set to RX1, be sure the negative ends of C19 and C20 are securely grounded (zero ohms) to chassis. Any resistance here would definitely produce ripple in the B+.

OK, so a little update with this radio:

I changed out the 5Z4 for a 5Y3G tube and installed a 6V6G tube into the radio and the hum has gone away, but a new issue as arisen, whenever I touch the chassis anywhere including the knobs or ground my signal generator to the chassis, the radio goes completely silent.
But then when I remove my hand or the signal generator ground clip from the chassis or from any of the knobs, the radio comes to life.

Is it because with this radio being made to utilize the metal tubes they had one of the heater pins grounded to the shield pin of those tubes and thus to the chassis?

If so should I go and unground those heater pins to make this radio work with more modern glass tubes?

Well I got it working, unfortunately it has to be turned up full blast in order to hear anything on it, which is what you guys warned me about with this unit because of its lack of AVC circuitry, the hum is still there but its not nearly as bad as it was, in fact when I turn the volume up all the way the hum goes away.

Unfortunately I couldn't tell how good the reception was on it because my housemate (who caught covid from his dad) had his desktop computer running (which is a high end gaming desktop) which has a super noisy power supply which basically renders AM Radio useless in my house, it just sounds like a a bunch of hash noise, across the whole dial with one local station that manages to break through the noise, the weird thing is that the noise seems to be not only on the AC line but also radiated through the air because even my battery radios are affected by the noise...:scratch2::sigh:

PCs with plexiglass view windows tend to radiate RF noise as as do many cheap power supplies. When I built my PC I went with a full metal case and a Bequiet brand power supply which doesn't seem to emit any noise to hamper radio or TV reception in the slightest.

PCs with plexiglass view windows tend to radiate RF noise as as do many cheap power supplies. When I built my PC I went with a full metal case and a Bequiet brand power supply which doesn't seem to emit any noise to hamper radio or TV reception in the slightest.

That's weird because I have a completely metal case on my computer I have now and it has a fairly expensive looking power supply in it and mine is pretty noisy, compared to my old computer which was a see through case and had a medium priced power supply and it hardly radiated any RF Noise, and then my housemate's computer is also an all metal case and I'm pretty sure he had a higher end power supply installed in it, but his computer is noisy RF wise, so I'm not sure what to say about that. :scratch2:

That's weird because I have a completely metal case on my computer I have now and it has a fairly expensive looking power supply in it and mine is pretty noisy, compared to my old computer which was a see through case and had a medium priced power supply and it hardly radiated any RF Noise, and then my housemate's computer is also an all metal case and I'm pretty sure he had a higher end power supply installed in it, but his computer is noisy RF wise, so I'm not sure what to say about that. :scratch2:

Just because you paid a lot for a power supply doesn't mean you're not buying a cheap crappy one with a highway robbery markup... Overpriced crap exists in every market.

Just because you paid a lot for a power supply doesn't mean you're not buying a cheap crappy one with a highway robbery markup... Overpriced crap exists in every market.

I'm going to go to the local computer store and see what they have as far as a computer power supplies go.

OK So I managed to pick up at a local computer store a 700W EVGA Branded power supply for $85 and I Installed it in my computer and its dead silent as far as EMI/RFI noise goes.

Unfortunately my housemate's power supply is still as mean, nasty and noisy as ever.

In fact, I took my recently acquired Sony AM only transistor radio around the house and I figured out (and I should of figured it out sooner) that my Housemate's computer power supply is using the whole house's wiring system as a giant antenna (think of those old capacitive coupled FM Antennas from back in the day that used to use the whole house wiring system as a giant FM Dipole Antenna) and so the EMI/RFI noise being emitted by my housemate's computer power supply is being radiated all throughout the house via the house's old ungrounded romex wiring (yes you heard that right UNGROUNDED romex wiring).

The fact that this house is still utilizing its original 90+ year old ungrounded romex wiring that is being concealed with modern grounded outlets (that are actually ungrounded clear back to the breaker box) that is why the my radios are affected by EMI/RFI noise so easily, including battery sets, because the
el cheapo computer power supplies are acting like a small radio transmitter of sorts and radiating a "radio signal" all through out the house with the ungrounded wiring acting as an "antenna" of sorts.

OK So I managed to pick up at a local computer store a 700W EVGA Branded power supply for $85 and I Installed it in my computer and its dead silent as far as EMI/RFI noise goes.

Unfortunately my housemate's power supply is still as mean, nasty and noisy as ever.

In fact, I took my recently acquired Sony AM only transistor radio around the house and I figured out (and I should of figured it out sooner) that my Housemate's computer power supply is using the whole house's wiring system as a giant antenna (think of those old capacitive coupled FM Antennas from back in the day that used to use the whole house wiring system as a giant FM Dipole Antenna) and so the EMI/RFI noise being emitted by my housemate's computer power supply is being radiated all throughout the house via the house's old ungrounded romex wiring (yes you heard that right UNGROUNDED romex wiring).

The fact that this house is still utilizing its original 90+ year old ungrounded romex wiring that is being concealed with modern grounded outlets (that are actually ungrounded clear back to the breaker box) that is why the my radios are affected by EMI/RFI noise so easily, including battery sets, because the
el cheapo computer power supplies are acting like a small radio transmitter of sorts and radiating a "radio signal" all through out the house with the ungrounded wiring acting as an "antenna" of sorts.
I don't know if Romex was around 90 years ago. The house might be wired in BX cable. BX has been around since the early 20's. It has a flexible steel armor.
Anyway, it's a code violation to install a grounding receptacle to replace a non grounding receptacle, unless it can be effectively grounded.
Some shady electricians tie the neutral conductor to the ground terminal to appear that the receptacle is grounded. :nono:

I don't know if Romex was around 90 years ago. The house might be wired in BX cable. BX has been around since the early 20's. It has a flexible steel armor.
Anyway, it's a code violation to install a grounding receptacle to replace a non grounding receptacle, unless it can be effectively grounded.
Some shady electricians tie the neutral conductor to the ground terminal to appear that the receptacle is grounded. :nono:

I'm sure its Romex, very early Romex, its got a black cloth outer sheathing and then 2 inner rubber insulated solid copper conductors (black and white respectively for hot and neutral), no grounding conductors present whatsoever.

My guess is that the lack of a grounding conductor at the box and going elsewhere in the house is why there's so much RFI/EMI Noise radiating throughout the house from my housemate's computer power supply.

My landlord when he bought this house for his son (my housemate) he had the house completely gutted supposedly and redone, which when they did that, I'm kind of surprised that he didn't have the place wired up to code, but he didn't I think he just more or less just "put lipstick on the pig" so to speak and called it good enough.

In other words he left the old ungrounded wiring in place and put grounded outlets into place to hide the fact that there was no grounded wiring in place and just went from there.

I'm actually surprised this place passed inspection with as many corners as they cut.

I can get a picture of the old wiring for you so you can see what it is that's in my house.

I've only seen 2 conductor Romex in use once. The old family cabin used black plastic 2 wire Romex to connect the outhouse (2 light sockets and an outlet) to the main building....the Romex was strung overhead from tree to tree. This was done sometime in the mid 60s-mid 70's when electricity became available there.

I've only seen 2 conductor Romex in use once. The old family cabin used black plastic 2 wire Romex to connect the outhouse (2 light sockets and an outlet) to the main building....the Romex was strung overhead from tree to tree. This was done sometime in the mid 60s-mid 70's when electricity became available there.

OK I figured out what is in my house, its first generation Non-Metallic Sheathed Wiring, aka Romex like I was stating before, the stuff in my place uses a rubberized cloth outer sheathing and rubber insulated solid copper conductors, from what I was reading that kind of wiring only had a 25 year life expectancy and should be updated, unfortunately whenever I've pointed that out to my landlord he brushes it off.

Anyways the way this house is currently wired up, they have a mixture of original wirirng and modern wiring (where they spliced modern wiring into old wiring to extend or add to a circuit) and they installed modern grounded outlets and switches without any actual ground wires to speak of to hook to the aforementioned grounded outlets and switches, they even have several 10 amp breakers running 2 rooms worth of outlets which makes it difficult to run anything like a vacuum without popping a breaker.

That's just to give you an idea of what i have to work with in my house, wiring wise, unfortunately its not my place, I'm just a renter so I can't do anything about the wiring in the house.

See pictures below.

OK I figured out what is in my house, its first generation Non-Metallic Sheathed Wiring, aka Romex like I was stating before, the stuff in my place uses a rubberized cloth outer sheathing and rubber insulated solid copper conductors, from what I was reading that kind of wiring only had a 25 year life expectancy and should be updated, unfortunately whenever I've pointed that out to my landlord he brushes it off.

Anyways the way this house is currently wired up, they have a mixture of original wirirng and modern wiring (where they spliced modern wiring into old wiring to extend or add to a circuit) and they installed modern grounded outlets and switches without any actual ground wires to speak of to hook to the aforementioned grounded outlets and switches, they even have several 10 amp breakers running 2 rooms worth of outlets which makes it difficult to run anything like a vacuum without popping a breaker.

That's just to give you an idea of what i have to work with in my house, wiring wise, unfortunately its not my place, I'm just a renter so I can't do anything about the wiring in the house.

See pictures below.
Not too much pride in workmanship shown there!
Pex water lines, mixed with rigid plastic lines. :thumbsdn:
If the owner decides to sell this home later, a home inspector is going to cite all the faults.
Are you sure about the breaker rating? 15 amp is the smallest rating for a #14 wire.

Interesting history of wiring practice in the US:

https://wenatcheehomeinspection.com/wp-content/uploads/2019/04/History_of_Residential_Wiring_practices_in_the_USA-1.pdf

From above source:

“Nonmetallic Cable
Although nonmetallic-sheathed cable, or NM for short, was first listed and described in the NEC in 1926, it was actually invented a few years earlier by General Cable at their Rome Wire Division in Rome, NY, and marketed under the trade name “Romex®.” Today many installers still refer generically to NM cable as Romex. Early NM cable had their individual conductors jacket wrapped in a cotton braid that was impregnated with either a varnish or tar-like substance for moisture protection.
Around 1950, synthetic spun rayon was being permitted to replace the cotton thread in the jacket braid. Then in the early 1960’s, thermoplastic began replacing the braided jacket altogether, and by about 1970, most all NM cable had a PVC outer jacket, even though a braid was still permitted until 1984. Also in 1984, NM-B cable was developed and required to have 90°C rated individual conductors, and a 75°C outer jacket (see Fig. 4).
Until the early 1960’s, most NM cable for residential use did not have a grounding conductor. However, changes in the 1962 Code that mandated equipment grounding for all branch circuits popularized the use of NM cable with ground. Earlier versions of NM cable with ground permitted the grounding conductor to be No. 16 AWG for 14 and 12 gauge copper NM, and No. 14 AWG ground for 10 gauge copper NM. In 1969, new requirements no longer permitted an undersized grounding conductor for 14, 12 and 10 gauge NM cable.”

jr

Interesting history of wiring practice in the US:

https://wenatcheehomeinspection.com/wp-content/uploads/2019/04/History_of_Residential_Wiring_practices_in_the_USA-1.pdf

From above source:

“Nonmetallic Cable
Although nonmetallic-sheathed cable, or NM for short, was first listed and described in the NEC in 1926, it was actually invented a few years earlier by General Cable at their Rome Wire Division in Rome, NY, and marketed under the trade name “Romex®.” Today many installers still refer generically to NM cable as Romex. Early NM cable had their individual conductors jacket wrapped in a cotton braid that was impregnated with either a varnish or tar-like substance for moisture protection.
Around 1950, synthetic spun rayon was being permitted to replace the cotton thread in the jacket braid. Then in the early 1960’s, thermoplastic began replacing the braided jacket altogether, and by about 1970, most all NM cable had a PVC outer jacket, even though a braid was still permitted until 1984. Also in 1984, NM-B cable was developed and required to have 90°C rated individual conductors, and a 75°C outer jacket (see Fig. 4).
Until the early 1960’s, most NM cable for residential use did not have a grounding conductor. However, changes in the 1962 Code that mandated equipment grounding for all branch circuits popularized the use of NM cable with ground. Earlier versions of NM cable with ground permitted the grounding conductor to be No. 16 AWG for 14 and 12 gauge copper NM, and No. 14 AWG ground for 10 gauge copper NM. In 1969, new requirements no longer permitted an undersized grounding conductor for 14, 12 and 10 gauge NM cable.”

jr
It's a very informative website!
I not that familiar with Romex wiring after living in Milwaukee, county Wisconsin for 58 years. Romex was not allowed until the mid 70's.
I lived in three different old houses that were wired for electricity many years after they were built. They were wired in the mid 20's and it was all BX cable.
It was my understanding that the Electric Company subsidized the installation.

Not too much pride in workmanship shown there!
Pex water lines, mixed with rigid plastic lines. :thumbsdn:
If the owner decides to sell this home later, a home inspector is going to cite all the faults.
Are you sure about the breaker rating? 15 amp is the smallest rating for a #14 wire.

Yes, I'm sure, I know what I saw.

I was running some space heaters (oil filled radiators) one winter because my side of the house which used to be the garage that the previous owners of the place had converted it into additional living space, and so when they did it, they didn't do it correctly including the HVAC runs and insulation.

So my side of the house even with the heat cranked up wouldn't get above 55 degrees in the winter without the use of a space heater or two.

Unfortunately the breaker blew whenever I had the spaceheater(s) set on high and when I looked at the breaker that controlled the outlets that were in my office and bedroom (one half of my bedroom and one half of my office) I saw that the breaker was only rated for 10 amps.

When I pointed it out to my landlord he had an electrician come over and the electrician said that the 10 amp breaker was all that could be used on that circuit because of the size of wire that was being used (18AWG) which is the size of wire you would normally use to wire up a table lamp or an old radio but not to wire up several sets of outlets... :thumbsdn: :nono:

The odd thing is that the rest of the breakers in the house that are associated with several runs of outlets are 20 amp breakers. :scratch2:

Also another odd thing is that the only place where there's GFCI Outlets are in the bathrooms, they don't have any GFCIs in the Kitchen anywhere, which AFAIK NEC calls for GFCIs wherever you have outlets near a water source (e.g. a sink) that includes the kitchen.

So unfortunately there were lots of corners cut in this house, and part of the reason for that is because my landlord (my housemate's dad) is a cheapskate and always tries to get things done as cheaply as possible even if it means using repair guys that have questionable credentials in order to save a few bucks. :thumbsdn: :nono:

OK so a little update on this Radio, I think I may have figured out where the hum is coming from in this radio... The original speaker is where the hum is coming from, because the guy I bought this radio originally had a second radio just like this that he gave me to use for parts to get the one I bought from him up and running, and when I used the speaker from the parts unit on the radio, there was no hum to be heard, but as soon as I hooked it back up to the speaker, the hum came back! :thumbsdn:

So I'm wondering if the filter choke (L15) which is the coil that is in the back of the speaker assembly (see picture below) is bad?

Would a bad filter choke cause the kind of hum that I've been describing that I've been having issues with on this radio?

It's possible. If you have swapped a second identical speaker and observed normal hum free opperation (which is what I think I read in your post) then you have confirmed something is not right with the first speaker.

What I would be looking at is the HUM BUCKING coil in the problem speaker. A large portion of electrodynamic (field coil type) speakers place a hum bucking coil in series with a lead of the voice coil. The hum bucking coil is typically a few turns on the same coil form as the field coil. The hum bucking coil acts like a secondary winding on a transformer formed by it and the field coil. The hum bucking coil picks up the AC hum in the field coil and feeds it into the voice coil 180 degrees out of phase. Ideally if the hum bucking has correct phase and amplitude it will perfectly cancell out any hum from the field coil so it doesn't produce audible sound.

If the hum bucking coil is connected with reverse phasing (read that polarity) instead of cancelling the hum it will double the hum (double the hum that would be there if you shorted the hum bucking coil or removed it from circuit which it's self would be worse hum than if the coil was working properly).

Also if the hum bucking coil, the voice coil or the audio output transformer secondary short to ground or B+ it could mess with hum bucking coil opperation.

It's possible. If you have swapped a second identical speaker and observed normal hum free opperation (which is what I think I read in your post) then you have confirmed something is not right with the first speaker.

What I would be looking at is the HUM BUCKING coil in the problem speaker. A large portion of electrodynamic (field coil type) speakers place a hum bucking coil in series with a lead of the voice coil. The hum bucking coil is typically a few turns on the same coil form as the field coil. The hum bucking coil acts like a secondary winding on a transformer formed by it and the field coil. The hum bucking coil picks up the AC hum in the field coil and feeds it into the voice coil 180 degrees out of phase. Ideally if the hum bucking has correct phase and amplitude it will perfectly cancell out any hum from the field coil so it doesn't produce audible sound.

If the hum bucking coil is connected with reverse phasing (read that polarity) instead of cancelling the hum it will double the hum (double the hum that would be there if you shorted the hum bucking coil or removed it from circuit which it's self would be worse hum than if the coil was working properly).

Also if the hum bucking coil, the voice coil or the audio output transformer secondary short to ground or B+ it could mess with hum bucking coil opperation.

Could it be possible for the speaker to be hooked up incorrectly?

The reason I ask is that the connection plug on the speaker where the speaker plug from the radio chassis plugs into doesn't really have any keying so the plug can go in any way you want (it's a 5 pin plug but only 4 of the pins are actually used) and there really aren't any markings to show which wires are what, and also the color of the wires are faded so badly that you can't tell which color is which on the wires.

If it uses the same 30s 5-pin socket/base as a type 76 tube (common speaker plug into the octal era) then it is in a way keyed such that it only plugs in one way. There's 4 pins closely clustered and a 5th pin off a ways....pin spacing is not symmetrical in both axes so it will only plug in one way (unless you break it).

If it uses the same 30s 5-pin socket/base as a type 76 tube (common speaker plug into the octal era) then it is in a way keyed such that it only plugs in one way. There's 4 pins closely clustered and a 5th pin off a ways....pin spacing is not symmetrical in both axes so it will only plug in one way (unless you break it).

Well that's the thing the plug coming out of the radio itself is broken, it's broken on one of the sides that has the close together pins.

But I think though that more than likely it's the hum bucking coil, that's bad, like I already suggested, I was just throwing that out there as an alternative idea.

You could try bypassing the bucking coil or reversing the leads and see if hum improves.

You could try bypassing the bucking coil or reversing the leads and see if hum improves.

How would I do that? Which wires go to the hum bucking coil? I'm asking because I don't want to accidentally cut the wrong wires.

I'm guessing the hum bucking coil is the black and white wires coming out of the coil on the back of the speaker shown in the picture below?

OK, so a little update, I removed the original speaker from the cabinet and replaced the original speaker plug with the one from my parts unit, and hooked the original speaker up to the radio with it outside the cabinet and no hum! So was it maybe something weird with the old speaker plug and something weird with the cabinet?

[QUOTE=vortalexfan;3238193]I'm guessing the hum bucking coil is the black and white wires coming out of the coil on the back of the speaker shown in the picture below?[/Q

I'm not familiar with that radio, but I'd guess the black and white wires are L16( the speaker field). The humbucking coil is a separate coil(likely sandwiched to one end of L16), that is wired in series with the voice coil. Reversing the field could have the same result as reversing the hum bucking coil, resulting in more hum. The way to figure that out is to try reversing it. Whichever way produces less hum is correct.

[QUOTE=vortalexfan;3238193]I'm guessing the hum bucking coil is the black and white wires coming out of the coil on the back of the speaker shown in the picture below?[/Q

I'm not familiar with that radio, but I'd guess the black and white wires are L16( the speaker field). The humbucking coil is a separate coil(likely sandwiched to one end of L16), that is wired in series with the voice coil. Reversing the field could have the same result as reversing the hum bucking coil, resulting in more hum. The way to figure that out is to try reversing it. Whichever way produces less hum is correct.

Ok, so I'm not sure what would be different between the speaker being in the cabinet and out of the cabinet but with the speaker out of the cabinet the hum is non-existent, and I'm not sure if this would of affected it or not but I did replace the old broken speaker plug.

Partially because having the speaker on a baffle board allows it to reproduce the 60 hz frequency more efficiently. Without the cabinet the wave coming off the back of the cone partially cancels the wave off the front.

Partially because having the speaker on a baffle board allows it to reproduce the 60 hz frequency more efficiently. Without the cabinet the wave coming off the back of the cone partially cancels the wave off the front.

OK, well I'm going to try putting the speaker back into the cabinet and hook it up to the radio again and see if it still hums.

OK, so a little update, it was definitely the original speaker that was bad (bad humbucking coil) because I installed the speaker from the parts radio like this one, and it for sure was not humming whereas the original speaker that came with this radio did hum, in fact when I looked at the parts radio speaker and the original speaker for this radio, it actually looks like the original speaker was maybe missing its humbucking coil (it only had two wires coming out of the field coil whereas the parts speaker had 4 wires coming out of the field coil.):scratch2:

So now I can officially say that this radio is fixed, unfortunately though the parts radio's speaker was slightly smaller than the original speaker was, so I had to modify it slightly to make it fit in the cabinet. :thmbsp: