after restoring a radiola 28 catacomb, I have significant distortion. Could it be the capacitors? Does anyone happen to know what the values should be or where I might find this info? Many thanks!!

Hi Dan

Not many capacitors in a Radiola 28. Coupling is through transformers. Noticed schematic shows grid of the audio output tube open on the other side of interstage transformer. This will cause distortion. It should be connected to C- which can be - 4 1/2 volts.

http://www.nostalgiaair.org/PagesByModel/324/M0040324.pdf

Norm

:after restoring a radiola 28 catacomb, I have significant distortion. Could it be the capacitors? Does anyone happen to know what the values should be or where I might find this info? Many thanks!!

Hi Norm,
Thank you for getting back to me. The catacomb has 9 capacitors in it and I am concerned that I might have damaged them when I melted the wax to expose the components. The resistance measures high on the capacitors but I can't measure the capacitace with any accuracy. Could distortion come from an open capacitor or only from one that leaks? I forgot to mention before that I am using solid state tubes that work well in other sets and not using C voltage. Would you have an idea of what the "usual" values of these capacitors might be? Thanx again for your help!!

:Hi Dan
:
: Not many capacitors in a Radiola 28. Coupling is through transformers. Noticed schematic shows grid of the audio output tube open on the other side of interstage transformer. This will cause distortion. It should be connected to C- which can be - 4 1/2 volts.
:
:http://www.nostalgiaair.org/PagesByModel/324/M0040324.pdf
:
:Norm
:
::after restoring a radiola 28 catacomb, I have significant distortion. Could it be the capacitors? Does anyone happen to know what the values should be or where I might find this info? Many thanks!!

The cap values will be rather small by today's standards. It maybe that some of the distortion is in the solid state tubes themselves driving oneof the stages to clipping- if you can, check each stage with a scope until you find that area where it is clipping and see if you can reduce the gain of the "tube" preceding it.

Also-have you grounded the "C-" lead by chance? If not try that first. Otherwise try swapping some of the "tubes" around that will swap to see if you can reduce some of the noise. You might even have a situation where you either need to reduce the "B voltage", or put in a "non-gain" tube.

:Hi Norm,
:Thank you for getting back to me. The catacomb has 9 capacitors in it and I am concerned that I might have damaged them when I melted the wax to expose the components. The resistance measures high on the capacitors but I can't measure the capacitace with any accuracy. Could distortion come from an open capacitor or only from one that leaks? I forgot to mention before that I am using solid state tubes that work well in other sets and not using C voltage. Would you have an idea of what the "usual" values of these capacitors might be? Thanx again for your help!!
:
::Hi Dan
::
:: Not many capacitors in a Radiola 28. Coupling is through transformers. Noticed schematic shows grid of the audio output tube open on the other side of interstage transformer. This will cause distortion. It should be connected to C- which can be - 4 1/2 volts.
::
::http://www.nostalgiaair.org/PagesByModel/324/M0040324.pdf
::
::Norm
::
:::after restoring a radiola 28 catacomb, I have significant distortion. Could it be the capacitors? Does anyone happen to know what the values should be or where I might find this info? Many thanks!!