On my model 635 Philco I got a squeal and loud shrill whistle on weak stations and when turning the volume control slightly one way or another it usually quit. I recapped and repaired all block capacitors and there was improvement but still some squealing.

You may need to take apart the volume control. Clean it up good, check for any bad or open spots on the disk. That seems to be a common problem.

Hi John

Be sure tube shield are in place. Might try cleaning the volume control. Just spray cleaning without opening might help.

The noise is a high frequency oscillation. If you tried everything and still have the problem add a small cap across the volume control. Try .001 mf. This will reduce some high frequency response.

Does the problem happen with tone control set to reduce high frequency response?

Norm

:On my model 635 Philco I got a squeal and loud shrill whistle on weak stations and when turning the volume control slightly one way or another it usually quit. I recapped and repaired all block capacitors and there was improvement but still some squealing.

:Hi John
:
: Be sure tube shield are in place. Might try cleaning the volume control. Just spray cleaning without opening might help.
:
: The noise is a high frequency oscillation. If you tried everything and still have the problem add a small cap across the volume control. Try .001 mf. This will reduce some high frequency response.

I tried cleaning the volume control and gets some better but I even replaced it completely and still get the squealing at times so don't think that's the answer. All shields are in place. The strange thing about it is it never seems to squeal if I turn the tone control fullyclockwise but this cuts down on the volume significantly. Any other of the two positions of the tone control it will squeal.
:
: Does the problem happen with tone control set to reduce high frequency response?
:
:Norm
:
::On my model 635 Philco I got a squeal and loud shrill whistle on weak stations and when turning the volume control slightly one way or another it usually quit. I recapped and repaired all block capacitors and there was improvement but still some squealing.

::Hi John
::
:: Be sure tube shield are in place. Might try cleaning the volume control. Just spray cleaning without opening might help.
::
:: The noise is a high frequency oscillation. If you tried everything and still have the problem add a small cap across the volume control. Try .001 mf. This will reduce some high frequency response.
:
:I tried cleaning the volume control and gets some better but I even replaced it completely and still get the squealing at times so don't think that's the answer. All shields are in place. The strange thing about it is it never seems to squeal if I turn the tone control fullyclockwise but this cuts down on the volume significantly. Any other of the two positions of the tone control it will squeal.
::
:: Does the problem happen with tone control set to reduce high frequency response?
::
::Norm
::
:::On my model 635 Philco I got a squeal and loud shrill whistle on weak stations and when turning the volume control slightly one way or another it usually quit. I recapped and repaired all block capacitors and there was improvement but still some squealing.

Another strange thing is that the schematic shows one end of the volume control going to ground but the radio was not wired this way. I grounded one end of the control and it doesn't seem to matter but left it grounded. This radio has an antenna clip place and also a ground clip place and I haven't hooked up the ground to anything so wonder if that is the problem.

:::Hi John
:::
::: Be sure tube shield are in place. Might try cleaning the volume control. Just spray cleaning without opening might help.
:::
::: The noise is a high frequency oscillation. If you tried everything and still have the problem add a small cap across the volume control. Try .001 mf. This will reduce some high frequency response.
::
::I tried cleaning the volume control and gets some better but I even replaced it completely and still get the squealing at times so don't think that's the answer. All shields are in place. The strange thing about it is it never seems to squeal if I turn the tone control fullyclockwise but this cuts down on the volume significantly. Any other of the two positions of the tone control it will squeal.
:::
::: Does the problem happen with tone control set to reduce high frequency response?
:::
:::Norm
:::
::::On my model 635 Philco I got a squeal and loud shrill whistle on weak stations and when turning the volume control slightly one way or another it usually quit. I recapped and repaired all block capacitors and there was improvement but still some squealing.
:
:Another strange thing is that the schematic shows one end of the volume control going to ground but the radio was not wired this way. I grounded one end of the control and it doesn't seem to matter but left it grounded. This radio has an antenna clip place and also a ground clip place and I haven't hooked up the ground to anything so wonder if that is the problem.

I tried the .001 across the volume control. Sounded like a really good idea but didn't help. Also, now have tried connecting the ground terminal and that didn't help. Seems to mostly squeel at higher volume levels as even on a strong station when the volume is turned up real loud you can hear it squeel in the background.

::::Hi John
::::
:::: Be sure tube shield are in place. Might try cleaning the volume control. Just spray cleaning without opening might help.
::::
:::: The noise is a high frequency oscillation. If you tried everything and still have the problem add a small cap across the volume control. Try .001 mf. This will reduce some high frequency response.
:::
:::I tried cleaning the volume control and gets some better but I even replaced it completely and still get the squealing at times so don't think that's the answer. All shields are in place. The strange thing about it is it never seems to squeal if I turn the tone control fullyclockwise but this cuts down on the volume significantly. Any other of the two positions of the tone control it will squeal.
::::
:::: Does the problem happen with tone control set to reduce high frequency response?
::::
::::Norm
::::
:::::On my model 635 Philco I got a squeal and loud shrill whistle on weak stations and when turning the volume control slightly one way or another it usually quit. I recapped and repaired all block capacitors and there was improvement but still some squealing.
::
::Another strange thing is that the schematic shows one end of the volume control going to ground but the radio was not wired this way. I grounded one end of the control and it doesn't seem to matter but left it grounded. This radio has an antenna clip place and also a ground clip place and I haven't hooked up the ground to anything so wonder if that is the problem.
:
:I tried the .001 across the volume control. Sounded like a really good idea but didn't help. Also, now have tried connecting the ground terminal and that didn't help. Seems to mostly squeel at higher volume levels as even on a strong station when the volume is turned up real loud you can hear it squeel in the backgrond

On weak stations, huh? I smell an AVC problem, meself. As the RF and IF gain go up, amybe some breaks into oscillation. An O-scope looking at the IF would be a nice check. OK, here's an idea. as you tune the dial slightly across the weak station that is oscillating, does the audio tone change?
Lewis

::Hi John
::
:: Be sure tube shield are in place. Might try cleaning the volume control. Just spray cleaning without opening might help.
::
:: The noise is a high frequency oscillation. If you tried everything and still have the problem add a small cap across the volume control. Try .001 mf. This will reduce some high frequency response.
:
:I tried cleaning the volume control and gets some better but I even replaced it completely and still get the squealing at times so don't think that's the answer. All shields are in place. The strange thing about it is it never seems to squeal if I turn the tone control fullyclockwise but this cuts down on the volume significantly. Any other of the two positions of the tone control it will squeal.
::
:: Does the problem happen with tone control set to reduce high frequency response?
::
::Norm
::
:::On my model 635 Philco I got a squeal and loud shrill whistle on weak stations and when turning the volume control slightly one way or another it usually quit. I recapped and repaired all block capacitors and there was improvement but still some squealing.

John, Check the grid wire to the type 75 tube. I'm not familiar with the model 635, but some of the Philcos required that the grid wire be routed inside the tube shield. Steve

:::Hi John
:::
::: Be sure tube shield are in place. Might try cleaning the volume control. Just spray cleaning without opening might help.
:::
::: The noise is a high frequency oscillation. If you tried everything and still have the problem add a small cap across the volume control. Try .001 mf. This will reduce some high frequency response.
::
::I tried cleaning the volume control and gets some better but I even replaced it completely and still get the squealing at times so don't think that's the answer. All shields are in place. The strange thing about it is it never seems to squeal if I turn the tone control fullyclockwise but this cuts down on the volume significantly. Any other of the two positions of the tone control it will squeal.
:::
::: Does the problem happen with tone control set to reduce high frequency response?
:::
:::Norm
:::
::::On my model 635 Philco I got a squeal and loud shrill whistle on weak stations and when turning the volume control slightly one way or another it usually quit. I recapped and repaired all block capacitors and there was improvement but still some squealing.
:
:John, Check the grid wire to the type 75 tube. I'm not familiar with the model 635, but some of the Philcos required that the grid wire be routed inside the tube shield. Steve

THANKS STEVE I looked and the grid wire of the 75 was outside the shield and near the 42 so when it squealed I moved the wire with a wooden stick and it would stop squealing and when I moved it back close to the 42 again it squealed so I think you have found the solution. Have been fighting this for 2 weeks. don't think I would have thought of this. THANKS, John