Does anyone have tube data for "GT" series tubes? I am working on a Philco 46-1226 which has a 5Y3GT rectifier, a 6J5GT inverter and 6K6GT audio outputs. The roll charts for my 920 do not show these, and I was nervous about just using the 6J5, 6K6 settings. Any help would be appreciated.

:Does anyone have tube data for "GT" series tubes? I am working on a Philco 46-1226 which has a 5Y3GT rectifier, a 6J5GT inverter and 6K6GT audio outputs. The roll charts for my 920 do not show these, and I was nervous about just using the 6J5, 6K6 settings. Any help would be appreciated.

Steve,

Should work. The 6J5GT and 6K6GT are the glass equivalent of the metal 6J5 and 6K6 respectively.

Radiodoc

::Does anyone have tube data for "GT" series tubes? I am working on a Philco 46-1226 which has a 5Y3GT rectifier, a 6J5GT inverter and 6K6GT audio outputs. The roll charts for my 920 do not show these, and I was nervous about just using the 6J5, 6K6 settings. Any help would be appreciated.
:
:Steve,
:
:Should work. The 6J5GT and 6K6GT are the glass equivalent of the metal 6J5 and 6K6 respectively.
:
:Radiodoc
:

Thanks, Radiodoc. I wasn't sure if they were the same or not. They tested as they should, but tested weak. Now the real question!!!! I have recapped the radio, checked all the IF's, the output xfmr, leads to speaker, speaker, etc, etc, and I can't get even a whisper of sound. Shouldn't I get a little bit of something at least - even if the tubes are weak?

Hi Steve

Measure voltage on pins #3 and #4 of your 6K6 tubes. Both should be positive. These tubes drive your speaker.

Measure voltage on pin #3 of your 6J5. This tube drives the 6K6's. Touch pin #5 on your 6J5. You should hear hum.

Weak tubes won't stop you from hearing hum in this test, unless they are almost dead.

http://www.nostalgiaair.org/PagesByModel/588/M0013588.pdf

Norm

:::Does anyone have tube data for "GT" series tubes? I am working on a Philco 46-1226 which has a 5Y3GT rectifier, a 6J5GT inverter and 6K6GT audio outputs. The roll charts for my 920 do not show these, and I was nervous about just using the 6J5, 6K6 settings. Any help would be appreciated.
::
::Steve,
::
::Should work. The 6J5GT and 6K6GT are the glass equivalent of the metal 6J5 and 6K6 respectively.
::
::Radiodoc
::
:
:Thanks, Radiodoc. I wasn't sure if they were the same or not. They tested as they should, but tested weak. Now the real question!!!! I have recapped the radio, checked all the IF's, the output xfmr, leads to speaker, speaker, etc, etc, and I can't get even a whisper of sound. Shouldn't I get a little bit of something at least - even if the tubes are weak?

Hi Norm,
Thanks for the direction. With positive lead on chassis grnd and negative lead on pins, I read 3 volts each. When touching pin #5 of 6J5 - deafening silence. One note - the schematic here is listed as Code 121. Mine is stamped Code 125 and has a 7AF7 instead of a 7F8.
Steve

:Hi Steve
:
: Measure voltage on pins #3 and #4 of your 6K6 tubes. Both should be positive. These tubes drive your speaker.
:
: Measure voltage on pin #3 of your 6J5. This tube drives the 6K6's. Touch pin #5 on your 6J5. You should hear hum.
:
: Weak tubes won't stop you from hearing hum in this test, unless they are almost dead.
:
:http://www.nostalgiaair.org/PagesByModel/588/M0013588.pdf
:
:Norm
:
:
::::Does anyone have tube data for "GT" series tubes? I am working on a Philco 46-1226 which has a 5Y3GT rectifier, a 6J5GT inverter and 6K6GT audio outputs. The roll charts for my 920 do not show these, and I was nervous about just using the 6J5, 6K6 settings. Any help would be appreciated.
:::
:::Steve,
:::
:::Should work. The 6J5GT and 6K6GT are the glass equivalent of the metal 6J5 and 6K6 respectively.
:::
:::Radiodoc
:::
::
::Thanks, Radiodoc. I wasn't sure if they were the same or not. They tested as they should, but tested weak. Now the real question!!!! I have recapped the radio, checked all the IF's, the output xfmr, leads to speaker, speaker, etc, etc, and I can't get even a whisper of sound. Shouldn't I get a little bit of something at least - even if the tubes are weak?

Hi Steve

Both tubes, 7AF7 and 7F8, are dual triodes. Either one will work but they are not interchangeable due to base wiring.

You are missing B+ voltage. Check pin #8 on your 5Y3. Should be 300 volts or more. From there it goes to a plug and the speaker field. Check resistance of the field. It may be open?

Norm

:Hi Norm,
:Thanks for the direction. With positive lead on chassis grnd and negative lead on pins, I read 3 volts each. When touching pin #5 of 6J5 - deafening silence. One note - the schematic here is listed as Code 121. Mine is stamped Code 125 and has a 7AF7 instead of a 7F8.
:Steve
:
::Hi Steve
::
:: Measure voltage on pins #3 and #4 of your 6K6 tubes. Both should be positive. These tubes drive your speaker.
::
:: Measure voltage on pin #3 of your 6J5. This tube drives the 6K6's. Touch pin #5 on your 6J5. You should hear hum.
::
:: Weak tubes won't stop you from hearing hum in this test, unless they are almost dead.
::
::http://www.nostalgiaair.org/PagesByModel/588/M0013588.pdf
::
::Norm
::
::
:::::Does anyone have tube data for "GT" series tubes? I am working on a Philco 46-1226 which has a 5Y3GT rectifier, a 6J5GT inverter and 6K6GT audio outputs. The roll charts for my 920 do not show these, and I was nervous about just using the 6J5, 6K6 settings. Any help would be appreciated.
::::
::::Steve,
::::
::::Should work. The 6J5GT and 6K6GT are the glass equivalent of the metal 6J5 and 6K6 respectively.
::::
::::Radiodoc
::::
:::
:::Thanks, Radiodoc. I wasn't sure if they were the same or not. They tested as they should, but tested weak. Now the real question!!!! I have recapped the radio, checked all the IF's, the output xfmr, leads to speaker, speaker, etc, etc, and I can't get even a whisper of sound. Shouldn't I get a little bit of something at least - even if the tubes are weak?

:Hi Steve
:
: Both tubes, 7AF7 and 7F8, are dual triodes. Either one will work but they are not interchangeable due to base wiring.
:
: You are missing B+ voltage. Check pin #8 on your 5Y3. Should be 300 volts or more. From there it goes to a plug and the speaker field. Check resistance of the field. It may be open?
:
:Norm

Steve,

The schematic I have for this radio shows a resistor in the high voltage centertap lead to ground. This could be open. I have had resistors in a similar location in other radios bad.

Radiodoc

:
::Hi Norm,
::Thanks for the direction. With positive lead on chassis grnd and negative lead on pins, I read 3 volts each. When touching pin #5 of 6J5 - deafening silence. One note - the schematic here is listed as Code 121. Mine is stamped Code 125 and has a 7AF7 instead of a 7F8.
::Steve
::
:::Hi Steve
:::
::: Measure voltage on pins #3 and #4 of your 6K6 tubes. Both should be positive. These tubes drive your speaker.
:::
::: Measure voltage on pin #3 of your 6J5. This tube drives the 6K6's. Touch pin #5 on your 6J5. You should hear hum.
:::
::: Weak tubes won't stop you from hearing hum in this test, unless they are almost dead.
:::
:::http://www.nostalgiaair.org/PagesByModel/588/M0013588.pdf
:::
:::Norm
:::
:::
::::::Does anyone have tube data for "GT" series tubes? I am working on a Philco 46-1226 which has a 5Y3GT rectifier, a 6J5GT inverter and 6K6GT audio outputs. The roll charts for my 920 do not show these, and I was nervous about just using the 6J5, 6K6 settings. Any help would be appreciated.
:::::
:::::Steve,
:::::
:::::Should work. The 6J5GT and 6K6GT are the glass equivalent of the metal 6J5 and 6K6 respectively.
:::::
:::::Radiodoc
:::::
::::
::::Thanks, Radiodoc. I wasn't sure if they were the same or not. They tested as they should, but tested weak. Now the real question!!!! I have recapped the radio, checked all the IF's, the output xfmr, leads to speaker, speaker, etc, etc, and I can't get even a whisper of sound. Shouldn't I get a little bit of something at least - even if the tubes are weak?

Hi again,
Norm, I have 350 volts at pin 8, but it looks as if you may have called it, Radiodoc. There is a resistor between pin 8 and the orange center tap of the AF Xfmr that is open. I could have sworn I checked that with all the others, but... It appears to be a tubular ceramic type, 1 3/4" long, 7/16" dia marked E33-1336-4. I'm not familiar with these. Any idea of the rating on this?
Steve

::Hi Steve
::
:: Both tubes, 7AF7 and 7F8, are dual triodes. Either one will work but they are not interchangeable due to base wiring.
::
:: You are missing B+ voltage. Check pin #8 on your 5Y3. Should be 300 volts or more. From there it goes to a plug and the speaker field. Check resistance of the field. It may be open?
::
::Norm
:
:Steve,
:
:The schematic I have for this radio shows a resistor in the high voltage centertap lead to ground. This could be open. I have had resistors in a similar location in other radios bad.
:
:Radiodoc
:
::
:::Hi Norm,
:::Thanks for the direction. With positive lead on chassis grnd and negative lead on pins, I read 3 volts each. When touching pin #5 of 6J5 - deafening silence. One note - the schematic here is listed as Code 121. Mine is stamped Code 125 and has a 7AF7 instead of a 7F8.
:::Steve
:::
::::Hi Steve
::::
:::: Measure voltage on pins #3 and #4 of your 6K6 tubes. Both should be positive. These tubes drive your speaker.
::::
:::: Measure voltage on pin #3 of your 6J5. This tube drives the 6K6's. Touch pin #5 on your 6J5. You should hear hum.
::::
:::: Weak tubes won't stop you from hearing hum in this test, unless they are almost dead.
::::
::::http://www.nostalgiaair.org/PagesByModel/588/M0013588.pdf
::::
::::Norm
::::
::::
:::::::Does anyone have tube data for "GT" series tubes? I am working on a Philco 46-1226 which has a 5Y3GT rectifier, a 6J5GT inverter and 6K6GT audio outputs. The roll charts for my 920 do not show these, and I was nervous about just using the 6J5, 6K6 settings. Any help would be appreciated.
::::::
::::::Steve,
::::::
::::::Should work. The 6J5GT and 6K6GT are the glass equivalent of the metal 6J5 and 6K6 respectively.
::::::
::::::Radiodoc
::::::
:::::
:::::Thanks, Radiodoc. I wasn't sure if they were the same or not. They tested as they should, but tested weak. Now the real question!!!! I have recapped the radio, checked all the IF's, the output xfmr, leads to speaker, speaker, etc, etc, and I can't get even a whisper of sound. Shouldn't I get a little bit of something at least - even if the tubes are weak?
:
:

:Hi again,
:Norm, I have 350 volts at pin 8, but it looks as if you may have called it, Radiodoc. There is a resistor between pin 8 and the orange center tap of the AF Xfmr that is open. I could have sworn I checked that with all the others, but... It appears to be a tubular ceramic type, 1 3/4" long, 7/16" dia marked E33-1336-4. I'm not familiar with these. Any idea of the rating on this?
:Steve
:
:
:::Hi Steve
:::
::: Both tubes, 7AF7 and 7F8, are dual triodes. Either one will work but they are not interchangeable due to base wiring.
:::
::: You are missing B+ voltage. Check pin #8 on your 5Y3. Should be 300 volts or more. From there it goes to a plug and the speaker field. Check resistance of the field. It may be open?
:::
:::Norm
::
::Steve,
::
::The schematic I have for this radio shows a resistor in the high voltage centertap lead to ground. This could be open. I have had resistors in a similar location in other radios bad.
::
::Radiodoc
::
:::
::::Hi Norm,
::::Thanks for the direction. With positive lead on chassis grnd and negative lead on pins, I read 3 volts each. When touching pin #5 of 6J5 - deafening silence. One note - the schematic here is listed as Code 121. Mine is stamped Code 125 and has a 7AF7 instead of a 7F8.
::::Steve
::::
:::::Hi Steve
:::::
::::: Measure voltage on pins #3 and #4 of your 6K6 tubes. Both should be positive. These tubes drive your speaker.
:::::
::::: Measure voltage on pin #3 of your 6J5. This tube drives the 6K6's. Touch pin #5 on your 6J5. You should hear hum.
:::::
::::: Weak tubes won't stop you from hearing hum in this test, unless they are almost dead.
:::::
:::::http://www.nostalgiaair.org/PagesByModel/588/M0013588.pdf
:::::
:::::Norm
:::::
:::::
::::::::Does anyone have tube data for "GT" series tubes? I am working on a Philco 46-1226 which has a 5Y3GT rectifier, a 6J5GT inverter and 6K6GT audio outputs. The roll charts for my 920 do not show these, and I was nervous about just using the 6J5, 6K6 settings. Any help would be appreciated.
:::::::
:::::::Steve,
:::::::
:::::::Should work. The 6J5GT and 6K6GT are the glass equivalent of the metal 6J5 and 6K6 respectively.
:::::::
:::::::Radiodoc
:::::::
::::::
::::::Thanks, Radiodoc. I wasn't sure if they were the same or not. They tested as they should, but tested weak. Now the real question!!!! I have recapped the radio, checked all the IF's, the output xfmr, leads to speaker, speaker, etc, etc, and I can't get even a whisper of sound. Shouldn't I get a little bit of something at least - even if the tubes are weak?
::
::
Steve,

The schematic I have shows this resistor to be 165 Ohms. I would probably try a standard value resistor as close to this value as possible rated at 5 watts for good measure.

Radiodoc

Thanks Radiodoc. And thanks again to Norm. I'll let you know what happens when I get a replacement.
Steve

::Hi again,
::Norm, I have 350 volts at pin 8, but it looks as if you may have called it, Radiodoc. There is a resistor between pin 8 and the orange center tap of the AF Xfmr that is open. I could have sworn I checked that with all the others, but... It appears to be a tubular ceramic type, 1 3/4" long, 7/16" dia marked E33-1336-4. I'm not familiar with these. Any idea of the rating on this?
::Steve
::
::
::::Hi Steve
::::
:::: Both tubes, 7AF7 and 7F8, are dual triodes. Either one will work but they are not interchangeable due to base wiring.
::::
:::: You are missing B+ voltage. Check pin #8 on your 5Y3. Should be 300 volts or more. From there it goes to a plug and the speaker field. Check resistance of the field. It may be open?
::::
::::Norm
:::
:::Steve,
:::
:::The schematic I have for this radio shows a resistor in the high voltage centertap lead to ground. This could be open. I have had resistors in a similar location in other radios bad.
:::
:::Radiodoc
:::
::::
:::::Hi Norm,
:::::Thanks for the direction. With positive lead on chassis grnd and negative lead on pins, I read 3 volts each. When touching pin #5 of 6J5 - deafening silence. One note - the schematic here is listed as Code 121. Mine is stamped Code 125 and has a 7AF7 instead of a 7F8.
:::::Steve
:::::
::::::Hi Steve
::::::
:::::: Measure voltage on pins #3 and #4 of your 6K6 tubes. Both should be positive. These tubes drive your speaker.
::::::
:::::: Measure voltage on pin #3 of your 6J5. This tube drives the 6K6's. Touch pin #5 on your 6J5. You should hear hum.
::::::
:::::: Weak tubes won't stop you from hearing hum in this test, unless they are almost dead.
::::::
::::::http://www.nostalgiaair.org/PagesByModel/588/M0013588.pdf
::::::
::::::Norm
::::::
::::::
:::::::::Does anyone have tube data for "GT" series tubes? I am working on a Philco 46-1226 which has a 5Y3GT rectifier, a 6J5GT inverter and 6K6GT audio outputs. The roll charts for my 920 do not show these, and I was nervous about just using the 6J5, 6K6 settings. Any help would be appreciated.
::::::::
::::::::Steve,
::::::::
::::::::Should work. The 6J5GT and 6K6GT are the glass equivalent of the metal 6J5 and 6K6 respectively.
::::::::
::::::::Radiodoc
::::::::
:::::::
:::::::Thanks, Radiodoc. I wasn't sure if they were the same or not. They tested as they should, but tested weak. Now the real question!!!! I have recapped the radio, checked all the IF's, the output xfmr, leads to speaker, speaker, etc, etc, and I can't get even a whisper of sound. Shouldn't I get a little bit of something at least - even if the tubes are weak?
:::
:::
:Steve,
:
:The schematic I have shows this resistor to be 165 Ohms. I would probably try a standard value resistor as close to this value as possible rated at 5 watts for good measure.
:
:Radiodoc
:

Radiodoc,
As I rechecked my schematic, I realized we were talking about two different resistors. The schematic I am using is from this site. It shows a 170 ohm resistor from T6 (green) to grnd. This one is fine. The open resistor on my chassis differs from my schematic in that it goes directly from pin #8 on the rectifier to the orange center tap of AF output T5. From this point it goes to C37+. It also has a 10K for R31 plus a 1200ohm from C37+ to C36/25mf+. C37, by the way, is dual electrolytic, 10mf & 25mf paralleled. The only wires to the speaker are the green and black from T5. Is your schematic closer to this? Any ideas?
Steve

:The schematic I have shows this resistor to be 165 Ohms. I would probably try a standard value resistor as close to this value as possible rated at 5 watts for good measure.
:
:Radiodoc

::Hi again,
::Norm, I have 350 volts at pin 8, but it looks as if you may have called it, Radiodoc. There is a resistor between pin 8 and the orange center tap of the AF Xfmr that is open. I could have sworn I checked that with all the others, but... It appears to be a tubular ceramic type, 1 3/4" long, 7/16" dia marked E33-1336-4. I'm not familiar with these. Any idea of the rating on this?
::Steve
::
::
::::Hi Steve
::::
:::: Both tubes, 7AF7 and 7F8, are dual triodes. Either one will work but they are not interchangeable due to base wiring.
::::
:::: You are missing B+ voltage. Check pin #8 on your 5Y3. Should be 300 volts or more. From there it goes to a plug and the speaker field. Check resistance of the field. It may be open?
::::
::::Norm
:::
:::Steve,
:::
:::The schematic I have for this radio shows a resistor in the high voltage centertap lead to ground. This could be open. I have had resistors in a similar location in other radios bad.
:::
:::Radiodoc
:::
::::
:::::Hi Norm,
:::::Thanks for the direction. With positive lead on chassis grnd and negative lead on pins, I read 3 volts each. When touching pin #5 of 6J5 - deafening silence. One note - the schematic here is listed as Code 121. Mine is stamped Code 125 and has a 7AF7 instead of a 7F8.
:::::Steve
:::::
::::::Hi Steve
::::::
:::::: Measure voltage on pins #3 and #4 of your 6K6 tubes. Both should be positive. These tubes drive your speaker.
::::::
:::::: Measure voltage on pin #3 of your 6J5. This tube drives the 6K6's. Touch pin #5 on your 6J5. You should hear hum.
::::::
:::::: Weak tubes won't stop you from hearing hum in this test, unless they are almost dead.
::::::
::::::http://www.nostalgiaair.org/PagesByModel/588/M0013588.pdf
::::::
::::::Norm
::::::
::::::
:::::::::Does anyone have tube data for "GT" series tubes? I am working on a Philco 46-1226 which has a 5Y3GT rectifier, a 6J5GT inverter and 6K6GT audio outputs. The roll charts for my 920 do not show these, and I was nervous about just using the 6J5, 6K6 settings. Any help would be appreciated.
::::::::
::::::::Steve,
::::::::
::::::::Should work. The 6J5GT and 6K6GT are the glass equivalent of the metal 6J5 and 6K6 respectively.
::::::::
::::::::Radiodoc
::::::::
:::::::
:::::::Thanks, Radiodoc. I wasn't sure if they were the same or not. They tested as they should, but tested weak. Now the real question!!!! I have recapped the radio, checked all the IF's, the output xfmr, leads to speaker, speaker, etc, etc, and I can't get even a whisper of sound. Shouldn't I get a little bit of something at least - even if the tubes are weak?
:::
:::
:Steve,
:

:Radiodoc,
:As I rechecked my schematic, I realized we were talking about two different resistors. The schematic I am using is from this site. It shows a 170 ohm resistor from T6 (green) to grnd. This one is fine. The open resistor on my chassis differs from my schematic in that it goes directly from pin #8 on the rectifier to the orange center tap of AF output T5. From this point it goes to C37+. It also has a 10K for R31 plus a 1200ohm from C37+ to C36/25mf+. C37, by the way, is dual electrolytic, 10mf & 25mf paralleled. The only wires to the speaker are the green and black from T5. Is your schematic closer to this? Any ideas?
:Steve
:

Hi Steve,

Has this radio had the dynamic speaker replaced with a PM (permanent magnet)? If I read your description right about a resistor from the rectifier to the output transformer center tap, then this resistor would be across what is/was the speaker field coil. If the speaker has been replaced with a PM type speaker then this resistor would take the place of of the old speaker field coil. Probably could get by with a 1000 ohm 10 watt resistor.

Radiodoc

::The schematic I have shows this resistor to be 165 Ohms. I would probably try a standard value resistor as close to this value as possible rated at 5 watts for good measure.
::
::Radiodoc
:
:
:
:::Hi again,
:::Norm, I have 350 volts at pin 8, but it looks as if you may have called it, Radiodoc. There is a resistor between pin 8 and the orange center tap of the AF Xfmr that is open. I could have sworn I checked that with all the others, but... It appears to be a tubular ceramic type, 1 3/4" long, 7/16" dia marked E33-1336-4. I'm not familiar with these. Any idea of the rating on this?
:::Steve
:::
:::
:::::Hi Steve
:::::
::::: Both tubes, 7AF7 and 7F8, are dual triodes. Either one will work but they are not interchangeable due to base wiring.
:::::
::::: You are missing B+ voltage. Check pin #8 on your 5Y3. Should be 300 volts or more. From there it goes to a plug and the speaker field. Check resistance of the field. It may be open?
:::::
:::::Norm
::::
::::Steve,
::::
::::The schematic I have for this radio shows a resistor in the high voltage centertap lead to ground. This could be open. I have had resistors in a similar location in other radios bad.
::::
::::Radiodoc
::::
:::::
::::::Hi Norm,
::::::Thanks for the direction. With positive lead on chassis grnd and negative lead on pins, I read 3 volts each. When touching pin #5 of 6J5 - deafening silence. One note - the schematic here is listed as Code 121. Mine is stamped Code 125 and has a 7AF7 instead of a 7F8.
::::::Steve
::::::
:::::::Hi Steve
:::::::
::::::: Measure voltage on pins #3 and #4 of your 6K6 tubes. Both should be positive. These tubes drive your speaker.
:::::::
::::::: Measure voltage on pin #3 of your 6J5. This tube drives the 6K6's. Touch pin #5 on your 6J5. You should hear hum.
:::::::
::::::: Weak tubes won't stop you from hearing hum in this test, unless they are almost dead.
:::::::
:::::::http://www.nostalgiaair.org/PagesByModel/588/M0013588.pdf
:::::::
:::::::Norm
:::::::
:::::::
::::::::::Does anyone have tube data for "GT" series tubes? I am working on a Philco 46-1226 which has a 5Y3GT rectifier, a 6J5GT inverter and 6K6GT audio outputs. The roll charts for my 920 do not show these, and I was nervous about just using the 6J5, 6K6 settings. Any help would be appreciated.
:::::::::
:::::::::Steve,
:::::::::
:::::::::Should work. The 6J5GT and 6K6GT are the glass equivalent of the metal 6J5 and 6K6 respectively.
:::::::::
:::::::::Radiodoc
:::::::::
::::::::
::::::::Thanks, Radiodoc. I wasn't sure if they were the same or not. They tested as they should, but tested weak. Now the real question!!!! I have recapped the radio, checked all the IF's, the output xfmr, leads to speaker, speaker, etc, etc, and I can't get even a whisper of sound. Shouldn't I get a little bit of something at least - even if the tubes are weak?
::::
::::
::Steve,
::
:

Hi again Radiodoc,
Yes, it is a PM speaker. I had known that but my pea brain couldn't put it together (can't tell I'm a novice, can ya.) If you can stand one last question - what may have caused the resistor to blow in the first place and/or what should I be watching for as I power it up again?
Steve

::Radiodoc,
::As I rechecked my schematic, I realized we were talking about two different resistors. The schematic I am using is from this site. It shows a 170 ohm resistor from T6 (green) to grnd. This one is fine. The open resistor on my chassis differs from my schematic in that it goes directly from pin #8 on the rectifier to the orange center tap of AF output T5. From this point it goes to C37+. It also has a 10K for R31 plus a 1200ohm from C37+ to C36/25mf+. C37, by the way, is dual electrolytic, 10mf & 25mf paralleled. The only wires to the speaker are the green and black from T5. Is your schematic closer to this? Any ideas?
::Steve
::
:
:Hi Steve,
:
:Has this radio had the dynamic speaker replaced with a PM (permanent magnet)? If I read your description right about a resistor from the rectifier to the output transformer center tap, then this resistor would be across what is/was the speaker field coil. If the speaker has been replaced with a PM type speaker then this resistor would take the place of of the old speaker field coil. Probably could get by with a 1000 ohm 10 watt resistor.
:
:Radiodoc
:
:
:::The schematic I have shows this resistor to be 165 Ohms. I would probably try a standard value resistor as close to this value as possible rated at 5 watts for good measure.
:::
:::Radiodoc
::
::
::
::::Hi again,
::::Norm, I have 350 volts at pin 8, but it looks as if you may have called it, Radiodoc. There is a resistor between pin 8 and the orange center tap of the AF Xfmr that is open. I could have sworn I checked that with all the others, but... It appears to be a tubular ceramic type, 1 3/4" long, 7/16" dia marked E33-1336-4. I'm not familiar with these. Any idea of the rating on this?
::::Steve
::::
::::
::::::Hi Steve
::::::
:::::: Both tubes, 7AF7 and 7F8, are dual triodes. Either one will work but they are not interchangeable due to base wiring.
::::::
:::::: You are missing B+ voltage. Check pin #8 on your 5Y3. Should be 300 volts or more. From there it goes to a plug and the speaker field. Check resistance of the field. It may be open?
::::::
::::::Norm
:::::
:::::Steve,
:::::
:::::The schematic I have for this radio shows a resistor in the high voltage centertap lead to ground. This could be open. I have had resistors in a similar location in other radios bad.
:::::
:::::Radiodoc
:::::
::::::
:::::::Hi Norm,
:::::::Thanks for the direction. With positive lead on chassis grnd and negative lead on pins, I read 3 volts each. When touching pin #5 of 6J5 - deafening silence. One note - the schematic here is listed as Code 121. Mine is stamped Code 125 and has a 7AF7 instead of a 7F8.
:::::::Steve
:::::::
::::::::Hi Steve
::::::::
:::::::: Measure voltage on pins #3 and #4 of your 6K6 tubes. Both should be positive. These tubes drive your speaker.
::::::::
:::::::: Measure voltage on pin #3 of your 6J5. This tube drives the 6K6's. Touch pin #5 on your 6J5. You should hear hum.
::::::::
:::::::: Weak tubes won't stop you from hearing hum in this test, unless they are almost dead.
::::::::
::::::::http://www.nostalgiaair.org/PagesByModel/588/M0013588.pdf
::::::::
::::::::Norm
::::::::
::::::::
:::::::::::Does anyone have tube data for "GT" series tubes? I am working on a Philco 46-1226 which has a 5Y3GT rectifier, a 6J5GT inverter and 6K6GT audio outputs. The roll charts for my 920 do not show these, and I was nervous about just using the 6J5, 6K6 settings. Any help would be appreciated.
::::::::::
::::::::::Steve,
::::::::::
::::::::::Should work. The 6J5GT and 6K6GT are the glass equivalent of the metal 6J5 and 6K6 respectively.
::::::::::
::::::::::Radiodoc
::::::::::
:::::::::
:::::::::Thanks, Radiodoc. I wasn't sure if they were the same or not. They tested as they should, but tested weak. Now the real question!!!! I have recapped the radio, checked all the IF's, the output xfmr, leads to speaker, speaker, etc, etc, and I can't get even a whisper of sound. Shouldn't I get a little bit of something at least - even if the tubes are weak?
:::::
:::::
:::Steve,
:::
::

:Hi again Radiodoc,
:Yes, it is a PM speaker. I had known that but my pea brain couldn't put it together (can't tell I'm a novice, can ya.) If you can stand one last question - what may have caused the resistor to blow in the first place and/or what should I be watching for as I power it up again?
:Steve
:

Hi Steve,

The resistor could have just failed after a period of years. A leaky cap. The wattage rating may have been too small. If you don't have a variac to slowly bring up the line voltage you can make a limiter using a lamp socket and extension cord. Just cut the hot lead and splice the lamp socket in. I use an incandesent lamp of about 50 or 60 watts in the socket. I plug the radio into the socket on the cord and plug the other end into the wall socket. If there is a serious problem the lamp will burn brightly otherwise it will probably light dimly. We all were novices at one time in one thing or another. I am very pleased that many younger persons have decided to try their hand at preserving the history of radio. Just be careful making measurements of voltages in this high voltage tube equipment. I use the one-hand-behind-my-back making measurements for safety.

Radiodoc

:::Radiodoc,
:::As I rechecked my schematic, I realized we were talking about two different resistors. The schematic I am using is from this site. It shows a 170 ohm resistor from T6 (green) to grnd. This one is fine. The open resistor on my chassis differs from my schematic in that it goes directly from pin #8 on the rectifier to the orange center tap of AF output T5. From this point it goes to C37+. It also has a 10K for R31 plus a 1200ohm from C37+ to C36/25mf+. C37, by the way, is dual electrolytic, 10mf & 25mf paralleled. The only wires to the speaker are the green and black from T5. Is your schematic closer to this? Any ideas?
:::Steve
:::
::
::Hi Steve,
::
::Has this radio had the dynamic speaker replaced with a PM (permanent magnet)? If I read your description right about a resistor from the rectifier to the output transformer center tap, then this resistor would be across what is/was the speaker field coil. If the speaker has been replaced with a PM type speaker then this resistor would take the place of of the old speaker field coil. Probably could get by with a 1000 ohm 10 watt resistor.
::
::Radiodoc
::
::
::::The schematic I have shows this resistor to be 165 Ohms. I would probably try a standard value resistor as close to this value as possible rated at 5 watts for good measure.
::::
::::Radiodoc
:::
:::
:::
:::::Hi again,
:::::Norm, I have 350 volts at pin 8, but it looks as if you may have called it, Radiodoc. There is a resistor between pin 8 and the orange center tap of the AF Xfmr that is open. I could have sworn I checked that with all the others, but... It appears to be a tubular ceramic type, 1 3/4" long, 7/16" dia marked E33-1336-4. I'm not familiar with these. Any idea of the rating on this?
:::::Steve
:::::
:::::
:::::::Hi Steve
:::::::
::::::: Both tubes, 7AF7 and 7F8, are dual triodes. Either one will work but they are not interchangeable due to base wiring.
:::::::
::::::: You are missing B+ voltage. Check pin #8 on your 5Y3. Should be 300 volts or more. From there it goes to a plug and the speaker field. Check resistance of the field. It may be open?
:::::::
:::::::Norm
::::::
::::::Steve,
::::::
::::::The schematic I have for this radio shows a resistor in the high voltage centertap lead to ground. This could be open. I have had resistors in a similar location in other radios bad.
::::::
::::::Radiodoc
::::::
:::::::
::::::::Hi Norm,
::::::::Thanks for the direction. With positive lead on chassis grnd and negative lead on pins, I read 3 volts each. When touching pin #5 of 6J5 - deafening silence. One note - the schematic here is listed as Code 121. Mine is stamped Code 125 and has a 7AF7 instead of a 7F8.
::::::::Steve
::::::::
:::::::::Hi Steve
:::::::::
::::::::: Measure voltage on pins #3 and #4 of your 6K6 tubes. Both should be positive. These tubes drive your speaker.
:::::::::
::::::::: Measure voltage on pin #3 of your 6J5. This tube drives the 6K6's. Touch pin #5 on your 6J5. You should hear hum.
:::::::::
::::::::: Weak tubes won't stop you from hearing hum in this test, unless they are almost dead.
:::::::::
:::::::::http://www.nostalgiaair.org/PagesByModel/588/M0013588.pdf
:::::::::
:::::::::Norm
:::::::::
:::::::::
::::::::::::Does anyone have tube data for "GT" series tubes? I am working on a Philco 46-1226 which has a 5Y3GT rectifier, a 6J5GT inverter and 6K6GT audio outputs. The roll charts for my 920 do not show these, and I was nervous about just using the 6J5, 6K6 settings. Any help would be appreciated.
:::::::::::
:::::::::::Steve,
:::::::::::
:::::::::::Should work. The 6J5GT and 6K6GT are the glass equivalent of the metal 6J5 and 6K6 respectively.
:::::::::::
:::::::::::Radiodoc
:::::::::::
::::::::::
::::::::::Thanks, Radiodoc. I wasn't sure if they were the same or not. They tested as they should, but tested weak. Now the real question!!!! I have recapped the radio, checked all the IF's, the output xfmr, leads to speaker, speaker, etc, etc, and I can't get even a whisper of sound. Shouldn't I get a little bit of something at least - even if the tubes are weak?
::::::
::::::
::::Steve,
::::
:::

Radiodoc,
It's alive!! I replaced the resistor and all works great. No static, no hum, loud and clear. Thanks again for all your help. It's really great having a site like this and folks like you willing to help.
Steve K

::Hi again Radiodoc,
::Yes, it is a PM speaker. I had known that but my pea brain couldn't put it together (can't tell I'm a novice, can ya.) If you can stand one last question - what may have caused the resistor to blow in the first place and/or what should I be watching for as I power it up again?
::Steve
::
:
:Hi Steve,
:
:The resistor could have just failed after a period of years. A leaky cap. The wattage rating may have been too small. If you don't have a variac to slowly bring up the line voltage you can make a limiter using a lamp socket and extension cord. Just cut the hot lead and splice the lamp socket in. I use an incandesent lamp of about 50 or 60 watts in the socket. I plug the radio into the socket on the cord and plug the other end into the wall socket. If there is a serious problem the lamp will burn brightly otherwise it will probably light dimly. We all were novices at one time in one thing or another. I am very pleased that many younger persons have decided to try their hand at preserving the history of radio. Just be careful making measurements of voltages in this high voltage tube equipment. I use the one-hand-behind-my-back making measurements for safety.
:
:Radiodoc
:
:
::::Radiodoc,
::::As I rechecked my schematic, I realized we were talking about two different resistors. The schematic I am using is from this site. It shows a 170 ohm resistor from T6 (green) to grnd. This one is fine. The open resistor on my chassis differs from my schematic in that it goes directly from pin #8 on the rectifier to the orange center tap of AF output T5. From this point it goes to C37+. It also has a 10K for R31 plus a 1200ohm from C37+ to C36/25mf+. C37, by the way, is dual electrolytic, 10mf & 25mf paralleled. The only wires to the speaker are the green and black from T5. Is your schematic closer to this? Any ideas?
::::Steve
::::
:::
:::Hi Steve,
:::
:::Has this radio had the dynamic speaker replaced with a PM (permanent magnet)? If I read your description right about a resistor from the rectifier to the output transformer center tap, then this resistor would be across what is/was the speaker field coil. If the speaker has been replaced with a PM type speaker then this resistor would take the place of of the old speaker field coil. Probably could get by with a 1000 ohm 10 watt resistor.
:::
:::Radiodoc
:::
:::
:::::The schematic I have shows this resistor to be 165 Ohms. I would probably try a standard value resistor as close to this value as possible rated at 5 watts for good measure.
:::::
:::::Radiodoc
::::
::::
::::
::::::Hi again,
::::::Norm, I have 350 volts at pin 8, but it looks as if you may have called it, Radiodoc. There is a resistor between pin 8 and the orange center tap of the AF Xfmr that is open. I could have sworn I checked that with all the others, but... It appears to be a tubular ceramic type, 1 3/4" long, 7/16" dia marked E33-1336-4. I'm not familiar with these. Any idea of the rating on this?
::::::Steve
::::::
::::::
::::::::Hi Steve
::::::::
:::::::: Both tubes, 7AF7 and 7F8, are dual triodes. Either one will work but they are not interchangeable due to base wiring.
::::::::
:::::::: You are missing B+ voltage. Check pin #8 on your 5Y3. Should be 300 volts or more. From there it goes to a plug and the speaker field. Check resistance of the field. It may be open?
::::::::
::::::::Norm
:::::::
:::::::Steve,
:::::::
:::::::The schematic I have for this radio shows a resistor in the high voltage centertap lead to ground. This could be open. I have had resistors in a similar location in other radios bad.
:::::::
:::::::Radiodoc
:::::::
::::::::
:::::::::Hi Norm,
:::::::::Thanks for the direction. With positive lead on chassis grnd and negative lead on pins, I read 3 volts each. When touching pin #5 of 6J5 - deafening silence. One note - the schematic here is listed as Code 121. Mine is stamped Code 125 and has a 7AF7 instead of a 7F8.
:::::::::Steve
:::::::::
::::::::::Hi Steve
::::::::::
:::::::::: Measure voltage on pins #3 and #4 of your 6K6 tubes. Both should be positive. These tubes drive your speaker.
::::::::::
:::::::::: Measure voltage on pin #3 of your 6J5. This tube drives the 6K6's. Touch pin #5 on your 6J5. You should hear hum.
::::::::::
:::::::::: Weak tubes won't stop you from hearing hum in this test, unless they are almost dead.
::::::::::
::::::::::http://www.nostalgiaair.org/PagesByModel/588/M0013588.pdf
::::::::::
::::::::::Norm
::::::::::
::::::::::
:::::::::::::Does anyone have tube data for "GT" series tubes? I am working on a Philco 46-1226 which has a 5Y3GT rectifier, a 6J5GT inverter and 6K6GT audio outputs. The roll charts for my 920 do not show these, and I was nervous about just using the 6J5, 6K6 settings. Any help would be appreciated.
::::::::::::
::::::::::::Steve,
::::::::::::
::::::::::::Should work. The 6J5GT and 6K6GT are the glass equivalent of the metal 6J5 and 6K6 respectively.
::::::::::::
::::::::::::Radiodoc
::::::::::::
:::::::::::
:::::::::::Thanks, Radiodoc. I wasn't sure if they were the same or not. They tested as they should, but tested weak. Now the real question!!!! I have recapped the radio, checked all the IF's, the output xfmr, leads to speaker, speaker, etc, etc, and I can't get even a whisper of sound. Shouldn't I get a little bit of something at least - even if the tubes are weak?
:::::::
:::::::
:::::Steve,
:::::
::::

:Radiodoc,
:It's alive!! I replaced the resistor and all works great. No static, no hum, loud and clear. Thanks again for all your help. It's really great having a site like this and folks like you willing to help.
:Steve K
:
Steve,

That's great. It's a nice feeling to when you get an oldtimer working again. You may be getting the bug. Best wishes and be careful when measuring voltages in these old ones.

Radiodoc

:::Hi again Radiodoc,
:::Yes, it is a PM speaker. I had known that but my pea brain couldn't put it together (can't tell I'm a novice, can ya.) If you can stand one last question - what may have caused the resistor to blow in the first place and/or what should I be watching for as I power it up again?
:::Steve
:::
::
::Hi Steve,
::
::The resistor could have just failed after a period of years. A leaky cap. The wattage rating may have been too small. If you don't have a variac to slowly bring up the line voltage you can make a limiter using a lamp socket and extension cord. Just cut the hot lead and splice the lamp socket in. I use an incandesent lamp of about 50 or 60 watts in the socket. I plug the radio into the socket on the cord and plug the other end into the wall socket. If there is a serious problem the lamp will burn brightly otherwise it will probably light dimly. We all were novices at one time in one thing or another. I am very pleased that many younger persons have decided to try their hand at preserving the history of radio. Just be careful making measurements of voltages in this high voltage tube equipment. I use the one-hand-behind-my-back making measurements for safety.
::
::Radiodoc
::
::
:::::Radiodoc,
:::::As I rechecked my schematic, I realized we were talking about two different resistors. The schematic I am using is from this site. It shows a 170 ohm resistor from T6 (green) to grnd. This one is fine. The open resistor on my chassis differs from my schematic in that it goes directly from pin #8 on the rectifier to the orange center tap of AF output T5. From this point it goes to C37+. It also has a 10K for R31 plus a 1200ohm from C37+ to C36/25mf+. C37, by the way, is dual electrolytic, 10mf & 25mf paralleled. The only wires to the speaker are the green and black from T5. Is your schematic closer to this? Any ideas?
:::::Steve
:::::
::::
::::Hi Steve,
::::
::::Has this radio had the dynamic speaker replaced with a PM (permanent magnet)? If I read your description right about a resistor from the rectifier to the output transformer center tap, then this resistor would be across what is/was the speaker field coil. If the speaker has been replaced with a PM type speaker then this resistor would take the place of of the old speaker field coil. Probably could get by with a 1000 ohm 10 watt resistor.
::::
::::Radiodoc
::::
::::
::::::The schematic I have shows this resistor to be 165 Ohms. I would probably try a standard value resistor as close to this value as possible rated at 5 watts for good measure.
::::::
::::::Radiodoc
:::::
:::::
:::::
:::::::Hi again,
:::::::Norm, I have 350 volts at pin 8, but it looks as if you may have called it, Radiodoc. There is a resistor between pin 8 and the orange center tap of the AF Xfmr that is open. I could have sworn I checked that with all the others, but... It appears to be a tubular ceramic type, 1 3/4" long, 7/16" dia marked E33-1336-4. I'm not familiar with these. Any idea of the rating on this?
:::::::Steve
:::::::
:::::::
:::::::::Hi Steve
:::::::::
::::::::: Both tubes, 7AF7 and 7F8, are dual triodes. Either one will work but they are not interchangeable due to base wiring.
:::::::::
::::::::: You are missing B+ voltage. Check pin #8 on your 5Y3. Should be 300 volts or more. From there it goes to a plug and the speaker field. Check resistance of the field. It may be open?
:::::::::
:::::::::Norm
::::::::
::::::::Steve,
::::::::
::::::::The schematic I have for this radio shows a resistor in the high voltage centertap lead to ground. This could be open. I have had resistors in a similar location in other radios bad.
::::::::
::::::::Radiodoc
::::::::
:::::::::
::::::::::Hi Norm,
::::::::::Thanks for the direction. With positive lead on chassis grnd and negative lead on pins, I read 3 volts each. When touching pin #5 of 6J5 - deafening silence. One note - the schematic here is listed as Code 121. Mine is stamped Code 125 and has a 7AF7 instead of a 7F8.
::::::::::Steve
::::::::::
:::::::::::Hi Steve
:::::::::::
::::::::::: Measure voltage on pins #3 and #4 of your 6K6 tubes. Both should be positive. These tubes drive your speaker.
:::::::::::
::::::::::: Measure voltage on pin #3 of your 6J5. This tube drives the 6K6's. Touch pin #5 on your 6J5. You should hear hum.
:::::::::::
::::::::::: Weak tubes won't stop you from hearing hum in this test, unless they are almost dead.
:::::::::::
:::::::::::http://www.nostalgiaair.org/PagesByModel/588/M0013588.pdf
:::::::::::
:::::::::::Norm
:::::::::::
:::::::::::
::::::::::::::Does anyone have tube data for "GT" series tubes? I am working on a Philco 46-1226 which has a 5Y3GT rectifier, a 6J5GT inverter and 6K6GT audio outputs. The roll charts for my 920 do not show these, and I was nervous about just using the 6J5, 6K6 settings. Any help would be appreciated.
:::::::::::::
:::::::::::::Steve,
:::::::::::::
:::::::::::::Should work. The 6J5GT and 6K6GT are the glass equivalent of the metal 6J5 and 6K6 respectively.
:::::::::::::
:::::::::::::Radiodoc
:::::::::::::
::::::::::::
::::::::::::Thanks, Radiodoc. I wasn't sure if they were the same or not. They tested as they should, but tested weak. Now the real question!!!! I have recapped the radio, checked all the IF's, the output xfmr, leads to speaker, speaker, etc, etc, and I can't get even a whisper of sound. Shouldn't I get a little bit of something at least - even if the tubes are weak?
::::::::
::::::::
::::::Steve,
::::::
:::::

Well hello again,
I have one last question - I hope. Everything seems to be working great here. The only concern I have is that the 1K resistor I installed gets VERY hot. I bumped it up to 25 watts, but it still cooks. It is a ceramic block type. Is there another type that would run cooler, or should I try another value?
Thanks for your help,
Steve

::Radiodoc,
::It's alive!! I replaced the resistor and all works great. No static, no hum, loud and clear. Thanks again for all your help. It's really great having a site like this and folks like you willing to help.
::Steve K
::
:Steve,
:
:That's great. It's a nice feeling to when you get an oldtimer working again. You may be getting the bug. Best wishes and be careful when measuring voltages in these old ones.
:
:Radiodoc
:
::::Hi again Radiodoc,
::::Yes, it is a PM speaker. I had known that but my pea brain couldn't put it together (can't tell I'm a novice, can ya.) If you can stand one last question - what may have caused the resistor to blow in the first place and/or what should I be watching for as I power it up again?
::::Steve
::::
:::
:::Hi Steve,
:::
:::The resistor could have just failed after a period of years. A leaky cap. The wattage rating may have been too small. If you don't have a variac to slowly bring up the line voltage you can make a limiter using a lamp socket and extension cord. Just cut the hot lead and splice the lamp socket in. I use an incandesent lamp of about 50 or 60 watts in the socket. I plug the radio into the socket on the cord and plug the other end into the wall socket. If there is a serious problem the lamp will burn brightly otherwise it will probably light dimly. We all were novices at one time in one thing or another. I am very pleased that many younger persons have decided to try their hand at preserving the history of radio. Just be careful making measurements of voltages in this high voltage tube equipment. I use the one-hand-behind-my-back making measurements for safety.
:::
:::Radiodoc
:::
:::
::::::Radiodoc,
::::::As I rechecked my schematic, I realized we were talking about two different resistors. The schematic I am using is from this site. It shows a 170 ohm resistor from T6 (green) to grnd. This one is fine. The open resistor on my chassis differs from my schematic in that it goes directly from pin #8 on the rectifier to the orange center tap of AF output T5. From this point it goes to C37+. It also has a 10K for R31 plus a 1200ohm from C37+ to C36/25mf+. C37, by the way, is dual electrolytic, 10mf & 25mf paralleled. The only wires to the speaker are the green and black from T5. Is your schematic closer to this? Any ideas?
::::::Steve
::::::
:::::
:::::Hi Steve,
:::::
:::::Has this radio had the dynamic speaker replaced with a PM (permanent magnet)? If I read your description right about a resistor from the rectifier to the output transformer center tap, then this resistor would be across what is/was the speaker field coil. If the speaker has been replaced with a PM type speaker then this resistor would take the place of of the old speaker field coil. Probably could get by with a 1000 ohm 10 watt resistor.
:::::
:::::Radiodoc
:::::
:::::
:::::::The schematic I have shows this resistor to be 165 Ohms. I would probably try a standard value resistor as close to this value as possible rated at 5 watts for good measure.
:::::::
:::::::Radiodoc
::::::
::::::
::::::
::::::::Hi again,
::::::::Norm, I have 350 volts at pin 8, but it looks as if you may have called it, Radiodoc. There is a resistor between pin 8 and the orange center tap of the AF Xfmr that is open. I could have sworn I checked that with all the others, but... It appears to be a tubular ceramic type, 1 3/4" long, 7/16" dia marked E33-1336-4. I'm not familiar with these. Any idea of the rating on this?
::::::::Steve
::::::::
::::::::
::::::::::Hi Steve
::::::::::
:::::::::: Both tubes, 7AF7 and 7F8, are dual triodes. Either one will work but they are not interchangeable due to base wiring.
::::::::::
:::::::::: You are missing B+ voltage. Check pin #8 on your 5Y3. Should be 300 volts or more. From there it goes to a plug and the speaker field. Check resistance of the field. It may be open?
::::::::::
::::::::::Norm
:::::::::
:::::::::Steve,
:::::::::
:::::::::The schematic I have for this radio shows a resistor in the high voltage centertap lead to ground. This could be open. I have had resistors in a similar location in other radios bad.
:::::::::
:::::::::Radiodoc
:::::::::
::::::::::
:::::::::::Hi Norm,
:::::::::::Thanks for the direction. With positive lead on chassis grnd and negative lead on pins, I read 3 volts each. When touching pin #5 of 6J5 - deafening silence. One note - the schematic here is listed as Code 121. Mine is stamped Code 125 and has a 7AF7 instead of a 7F8.
:::::::::::Steve
:::::::::::
::::::::::::Hi Steve
::::::::::::
:::::::::::: Measure voltage on pins #3 and #4 of your 6K6 tubes. Both should be positive. These tubes drive your speaker.
::::::::::::
:::::::::::: Measure voltage on pin #3 of your 6J5. This tube drives the 6K6's. Touch pin #5 on your 6J5. You should hear hum.
::::::::::::
:::::::::::: Weak tubes won't stop you from hearing hum in this test, unless they are almost dead.
::::::::::::
::::::::::::http://www.nostalgiaair.org/PagesByModel/588/M0013588.pdf
::::::::::::
::::::::::::Norm
::::::::::::
::::::::::::
:::::::::::::::Does anyone have tube data for "GT" series tubes? I am working on a Philco 46-1226 which has a 5Y3GT rectifier, a 6J5GT inverter and 6K6GT audio outputs. The roll charts for my 920 do not show these, and I was nervous about just using the 6J5, 6K6 settings. Any help would be appreciated.
::::::::::::::
::::::::::::::Steve,
::::::::::::::
::::::::::::::Should work. The 6J5GT and 6K6GT are the glass equivalent of the metal 6J5 and 6K6 respectively.
::::::::::::::
::::::::::::::Radiodoc
::::::::::::::
:::::::::::::
:::::::::::::Thanks, Radiodoc. I wasn't sure if they were the same or not. They tested as they should, but tested weak. Now the real question!!!! I have recapped the radio, checked all the IF's, the output xfmr, leads to speaker, speaker, etc, etc, and I can't get even a whisper of sound. Shouldn't I get a little bit of something at least - even if the tubes are weak?
:::::::::
:::::::::
:::::::Steve,
:::::::
::::::

:Well hello again,
:I have one last question - I hope. Everything seems to be working great here. The only concern I have is that the 1K resistor I installed gets VERY hot. I bumped it up to 25 watts, but it still cooks. It is a ceramic block type. Is there another type that would run cooler, or should I try another value?
:Thanks for your help,
:Steve
:
Steve,

Generally I would use a resistor somewhere around the value of the field coil resistance is it's resistance is known or shown on the schematic. However, sometimes I experiment with values up or down until I get close to what the plus voltage is according to that on the schematic. May have to trace it around to a plate and/or screen voltage on the output audio tube or tubes. I'll look at the schematic again this weekend and study it again. The resistor will get quite hot as there is a good bit of current through it.

Radiodoc

:
:
:
:
:::Radiodoc,
:::It's alive!! I replaced the resistor and all works great. No static, no hum, loud and clear. Thanks again for all your help. It's really great having a site like this and folks like you willing to help.
:::Steve K
:::
::Steve,
::
::That's great. It's a nice feeling to when you get an oldtimer working again. You may be getting the bug. Best wishes and be careful when measuring voltages in these old ones.
::
::Radiodoc
::
:::::Hi again Radiodoc,
:::::Yes, it is a PM speaker. I had known that but my pea brain couldn't put it together (can't tell I'm a novice, can ya.) If you can stand one last question - what may have caused the resistor to blow in the first place and/or what should I be watching for as I power it up again?
:::::Steve
:::::
::::
::::Hi Steve,
::::
::::The resistor could have just failed after a period of years. A leaky cap. The wattage rating may have been too small. If you don't have a variac to slowly bring up the line voltage you can make a limiter using a lamp socket and extension cord. Just cut the hot lead and splice the lamp socket in. I use an incandesent lamp of about 50 or 60 watts in the socket. I plug the radio into the socket on the cord and plug the other end into the wall socket. If there is a serious problem the lamp will burn brightly otherwise it will probably light dimly. We all were novices at one time in one thing or another. I am very pleased that many younger persons have decided to try their hand at preserving the history of radio. Just be careful making measurements of voltages in this high voltage tube equipment. I use the one-hand-behind-my-back making measurements for safety.
::::
::::Radiodoc
::::
::::
:::::::Radiodoc,
:::::::As I rechecked my schematic, I realized we were talking about two different resistors. The schematic I am using is from this site. It shows a 170 ohm resistor from T6 (green) to grnd. This one is fine. The open resistor on my chassis differs from my schematic in that it goes directly from pin #8 on the rectifier to the orange center tap of AF output T5. From this point it goes to C37+. It also has a 10K for R31 plus a 1200ohm from C37+ to C36/25mf+. C37, by the way, is dual electrolytic, 10mf & 25mf paralleled. The only wires to the speaker are the green and black from T5. Is your schematic closer to this? Any ideas?
:::::::Steve
:::::::
::::::
::::::Hi Steve,
::::::
::::::Has this radio had the dynamic speaker replaced with a PM (permanent magnet)? If I read your description right about a resistor from the rectifier to the output transformer center tap, then this resistor would be across what is/was the speaker field coil. If the speaker has been replaced with a PM type speaker then this resistor would take the place of of the old speaker field coil. Probably could get by with a 1000 ohm 10 watt resistor.
::::::
::::::Radiodoc
::::::
::::::
::::::::The schematic I have shows this resistor to be 165 Ohms. I would probably try a standard value resistor as close to this value as possible rated at 5 watts for good measure.
::::::::
::::::::Radiodoc
:::::::
:::::::
:::::::
:::::::::Hi again,
:::::::::Norm, I have 350 volts at pin 8, but it looks as if you may have called it, Radiodoc. There is a resistor between pin 8 and the orange center tap of the AF Xfmr that is open. I could have sworn I checked that with all the others, but... It appears to be a tubular ceramic type, 1 3/4" long, 7/16" dia marked E33-1336-4. I'm not familiar with these. Any idea of the rating on this?
:::::::::Steve
:::::::::
:::::::::
:::::::::::Hi Steve
:::::::::::
::::::::::: Both tubes, 7AF7 and 7F8, are dual triodes. Either one will work but they are not interchangeable due to base wiring.
:::::::::::
::::::::::: You are missing B+ voltage. Check pin #8 on your 5Y3. Should be 300 volts or more. From there it goes to a plug and the speaker field. Check resistance of the field. It may be open?
:::::::::::
:::::::::::Norm
::::::::::
::::::::::Steve,
::::::::::
::::::::::The schematic I have for this radio shows a resistor in the high voltage centertap lead to ground. This could be open. I have had resistors in a similar location in other radios bad.
::::::::::
::::::::::Radiodoc
::::::::::
:::::::::::
::::::::::::Hi Norm,
::::::::::::Thanks for the direction. With positive lead on chassis grnd and negative lead on pins, I read 3 volts each. When touching pin #5 of 6J5 - deafening silence. One note - the schematic here is listed as Code 121. Mine is stamped Code 125 and has a 7AF7 instead of a 7F8.
::::::::::::Steve
::::::::::::
:::::::::::::Hi Steve
:::::::::::::
::::::::::::: Measure voltage on pins #3 and #4 of your 6K6 tubes. Both should be positive. These tubes drive your speaker.
:::::::::::::
::::::::::::: Measure voltage on pin #3 of your 6J5. This tube drives the 6K6's. Touch pin #5 on your 6J5. You should hear hum.
:::::::::::::
::::::::::::: Weak tubes won't stop you from hearing hum in this test, unless they are almost dead.
:::::::::::::
:::::::::::::http://www.nostalgiaair.org/PagesByModel/588/M0013588.pdf
:::::::::::::
:::::::::::::Norm
:::::::::::::
:::::::::::::
::::::::::::::::Does anyone have tube data for "GT" series tubes? I am working on a Philco 46-1226 which has a 5Y3GT rectifier, a 6J5GT inverter and 6K6GT audio outputs. The roll charts for my 920 do not show these, and I was nervous about just using the 6J5, 6K6 settings. Any help would be appreciated.
:::::::::::::::
:::::::::::::::Steve,
:::::::::::::::
:::::::::::::::Should work. The 6J5GT and 6K6GT are the glass equivalent of the metal 6J5 and 6K6 respectively.
:::::::::::::::
:::::::::::::::Radiodoc
:::::::::::::::
::::::::::::::
::::::::::::::Thanks, Radiodoc. I wasn't sure if they were the same or not. They tested as they should, but tested weak. Now the real question!!!! I have recapped the radio, checked all the IF's, the output xfmr, leads to speaker, speaker, etc, etc, and I can't get even a whisper of sound. Shouldn't I get a little bit of something at least - even if the tubes are weak?
::::::::::
::::::::::
::::::::Steve,
::::::::
:::::::

Radiodoc,
Schematic shows field coil at 650 ohms. I could get a little closer. If the heat is not an issue then I'm not worried about it. Just wanted to make sure.
Steve

::Well hello again,
::I have one last question - I hope. Everything seems to be working great here. The only concern I have is that the 1K resistor I installed gets VERY hot. I bumped it up to 25 watts, but it still cooks. It is a ceramic block type. Is there another type that would run cooler, or should I try another value?
::Thanks for your help,
::Steve
::
:Steve,
:
:Generally I would use a resistor somewhere around the value of the field coil resistance is it's resistance is known or shown on the schematic. However, sometimes I experiment with values up or down until I get close to what the plus voltage is according to that on the schematic. May have to trace it around to a plate and/or screen voltage on the output audio tube or tubes. I'll look at the schematic again this weekend and study it again. The resistor will get quite hot as there is a good bit of current through it.
:
:Radiodoc
:
::
::
::
::
::::Radiodoc,
::::It's alive!! I replaced the resistor and all works great. No static, no hum, loud and clear. Thanks again for all your help. It's really great having a site like this and folks like you willing to help.
::::Steve K
::::
:::Steve,
:::
:::That's great. It's a nice feeling to when you get an oldtimer working again. You may be getting the bug. Best wishes and be careful when measuring voltages in these old ones.
:::
:::Radiodoc
:::
::::::Hi again Radiodoc,
::::::Yes, it is a PM speaker. I had known that but my pea brain couldn't put it together (can't tell I'm a novice, can ya.) If you can stand one last question - what may have caused the resistor to blow in the first place and/or what should I be watching for as I power it up again?
::::::Steve
::::::
:::::
:::::Hi Steve,
:::::
:::::The resistor could have just failed after a period of years. A leaky cap. The wattage rating may have been too small. If you don't have a variac to slowly bring up the line voltage you can make a limiter using a lamp socket and extension cord. Just cut the hot lead and splice the lamp socket in. I use an incandesent lamp of about 50 or 60 watts in the socket. I plug the radio into the socket on the cord and plug the other end into the wall socket. If there is a serious problem the lamp will burn brightly otherwise it will probably light dimly. We all were novices at one time in one thing or another. I am very pleased that many younger persons have decided to try their hand at preserving the history of radio. Just be careful making measurements of voltages in this high voltage tube equipment. I use the one-hand-behind-my-back making measurements for safety.
:::::
:::::Radiodoc
:::::
:::::
::::::::Radiodoc,
::::::::As I rechecked my schematic, I realized we were talking about two different resistors. The schematic I am using is from this site. It shows a 170 ohm resistor from T6 (green) to grnd. This one is fine. The open resistor on my chassis differs from my schematic in that it goes directly from pin #8 on the rectifier to the orange center tap of AF output T5. From this point it goes to C37+. It also has a 10K for R31 plus a 1200ohm from C37+ to C36/25mf+. C37, by the way, is dual electrolytic, 10mf & 25mf paralleled. The only wires to the speaker are the green and black from T5. Is your schematic closer to this? Any ideas?
::::::::Steve
::::::::
:::::::
:::::::Hi Steve,
:::::::
:::::::Has this radio had the dynamic speaker replaced with a PM (permanent magnet)? If I read your description right about a resistor from the rectifier to the output transformer center tap, then this resistor would be across what is/was the speaker field coil. If the speaker has been replaced with a PM type speaker then this resistor would take the place of of the old speaker field coil. Probably could get by with a 1000 ohm 10 watt resistor.
:::::::
:::::::Radiodoc
:::::::
:::::::
:::::::::The schematic I have shows this resistor to be 165 Ohms. I would probably try a standard value resistor as close to this value as possible rated at 5 watts for good measure.
:::::::::
:::::::::Radiodoc
::::::::
::::::::
::::::::
::::::::::Hi again,
::::::::::Norm, I have 350 volts at pin 8, but it looks as if you may have called it, Radiodoc. There is a resistor between pin 8 and the orange center tap of the AF Xfmr that is open. I could have sworn I checked that with all the others, but... It appears to be a tubular ceramic type, 1 3/4" long, 7/16" dia marked E33-1336-4. I'm not familiar with these. Any idea of the rating on this?
::::::::::Steve
::::::::::
::::::::::
::::::::::::Hi Steve
::::::::::::
:::::::::::: Both tubes, 7AF7 and 7F8, are dual triodes. Either one will work but they are not interchangeable due to base wiring.
::::::::::::
:::::::::::: You are missing B+ voltage. Check pin #8 on your 5Y3. Should be 300 volts or more. From there it goes to a plug and the speaker field. Check resistance of the field. It may be open?
::::::::::::
::::::::::::Norm
:::::::::::
:::::::::::Steve,
:::::::::::
:::::::::::The schematic I have for this radio shows a resistor in the high voltage centertap lead to ground. This could be open. I have had resistors in a similar location in other radios bad.
:::::::::::
:::::::::::Radiodoc
:::::::::::
::::::::::::
:::::::::::::Hi Norm,
:::::::::::::Thanks for the direction. With positive lead on chassis grnd and negative lead on pins, I read 3 volts each. When touching pin #5 of 6J5 - deafening silence. One note - the schematic here is listed as Code 121. Mine is stamped Code 125 and has a 7AF7 instead of a 7F8.
:::::::::::::Steve
:::::::::::::
::::::::::::::Hi Steve
::::::::::::::
:::::::::::::: Measure voltage on pins #3 and #4 of your 6K6 tubes. Both should be positive. These tubes drive your speaker.
::::::::::::::
:::::::::::::: Measure voltage on pin #3 of your 6J5. This tube drives the 6K6's. Touch pin #5 on your 6J5. You should hear hum.
::::::::::::::
:::::::::::::: Weak tubes won't stop you from hearing hum in this test, unless they are almost dead.
::::::::::::::
::::::::::::::http://www.nostalgiaair.org/PagesByModel/588/M0013588.pdf
::::::::::::::
::::::::::::::Norm
::::::::::::::
::::::::::::::
:::::::::::::::::Does anyone have tube data for "GT" series tubes? I am working on a Philco 46-1226 which has a 5Y3GT rectifier, a 6J5GT inverter and 6K6GT audio outputs. The roll charts for my 920 do not show these, and I was nervous about just using the 6J5, 6K6 settings. Any help would be appreciated.
::::::::::::::::
::::::::::::::::Steve,
::::::::::::::::
::::::::::::::::Should work. The 6J5GT and 6K6GT are the glass equivalent of the metal 6J5 and 6K6 respectively.
::::::::::::::::
::::::::::::::::Radiodoc
::::::::::::::::
:::::::::::::::
:::::::::::::::Thanks, Radiodoc. I wasn't sure if they were the same or not. They tested as they should, but tested weak. Now the real question!!!! I have recapped the radio, checked all the IF's, the output xfmr, leads to speaker, speaker, etc, etc, and I can't get even a whisper of sound. Shouldn't I get a little bit of something at least - even if the tubes are weak?
:::::::::::
:::::::::::
:::::::::Steve,
:::::::::
::::::::

:Radiodoc,
:Schematic shows field coil at 650 ohms. I could get a little closer. If the heat is not an issue then I'm not worried about it. Just wanted to make sure.
:Steve
:

Hi Steve,

You could parallel a couple of your 1000 Ohm resistors and tag them in there. This should give you approximately 500 Ohms. Check the voltage on the side of this resistor going to the CT of the output transformer and see if it is fairly close to what the schematic says. I believe my schematic shows arount plus 240 volts. Something else to check is to measure the voltage across R30. This is the bias voltage for the 6V6s. My print shows a minus 15 volts or so. Also measure the minus voltage on each pin 5 of the 6V6s and should be around minus 11 volts to minus 15 volts. I guesstimate the total current from the power supply to be around 90 milliamps. I was a little high on the value of the resistor to replace the field coil. Sorry about that. Even so a 500 Ohm resistor will get quite hot so make sure it is not too close to wire insulation and other components.

Radiodoc

:
:::Well hello again,
:::I have one last question - I hope. Everything seems to be working great here. The only concern I have is that the 1K resistor I installed gets VERY hot. I bumped it up to 25 watts, but it still cooks. It is a ceramic block type. Is there another type that would run cooler, or should I try another value?
:::Thanks for your help,
:::Steve
:::
::Steve,
::
::Generally I would use a resistor somewhere around the value of the field coil resistance is it's resistance is known or shown on the schematic. However, sometimes I experiment with values up or down until I get close to what the plus voltage is according to that on the schematic. May have to trace it around to a plate and/or screen voltage on the output audio tube or tubes. I'll look at the schematic again this weekend and study it again. The resistor will get quite hot as there is a good bit of current through it.
::
::Radiodoc
::
:::
:::
:::
:::
:::::Radiodoc,
:::::It's alive!! I replaced the resistor and all works great. No static, no hum, loud and clear. Thanks again for all your help. It's really great having a site like this and folks like you willing to help.
:::::Steve K
:::::
::::Steve,
::::
::::That's great. It's a nice feeling to when you get an oldtimer working again. You may be getting the bug. Best wishes and be careful when measuring voltages in these old ones.
::::
::::Radiodoc
::::
:::::::Hi again Radiodoc,
:::::::Yes, it is a PM speaker. I had known that but my pea brain couldn't put it together (can't tell I'm a novice, can ya.) If you can stand one last question - what may have caused the resistor to blow in the first place and/or what should I be watching for as I power it up again?
:::::::Steve
:::::::
::::::
::::::Hi Steve,
::::::
::::::The resistor could have just failed after a period of years. A leaky cap. The wattage rating may have been too small. If you don't have a variac to slowly bring up the line voltage you can make a limiter using a lamp socket and extension cord. Just cut the hot lead and splice the lamp socket in. I use an incandesent lamp of about 50 or 60 watts in the socket. I plug the radio into the socket on the cord and plug the other end into the wall socket. If there is a serious problem the lamp will burn brightly otherwise it will probably light dimly. We all were novices at one time in one thing or another. I am very pleased that many younger persons have decided to try their hand at preserving the history of radio. Just be careful making measurements of voltages in this high voltage tube equipment. I use the one-hand-behind-my-back making measurements for safety.
::::::
::::::Radiodoc
::::::
::::::
:::::::::Radiodoc,
:::::::::As I rechecked my schematic, I realized we were talking about two different resistors. The schematic I am using is from this site. It shows a 170 ohm resistor from T6 (green) to grnd. This one is fine. The open resistor on my chassis differs from my schematic in that it goes directly from pin #8 on the rectifier to the orange center tap of AF output T5. From this point it goes to C37+. It also has a 10K for R31 plus a 1200ohm from C37+ to C36/25mf+. C37, by the way, is dual electrolytic, 10mf & 25mf paralleled. The only wires to the speaker are the green and black from T5. Is your schematic closer to this? Any ideas?
:::::::::Steve
:::::::::
::::::::
::::::::Hi Steve,
::::::::
::::::::Has this radio had the dynamic speaker replaced with a PM (permanent magnet)? If I read your description right about a resistor from the rectifier to the output transformer center tap, then this resistor would be across what is/was the speaker field coil. If the speaker has been replaced with a PM type speaker then this resistor would take the place of of the old speaker field coil. Probably could get by with a 1000 ohm 10 watt resistor.
::::::::
::::::::Radiodoc
::::::::
::::::::
::::::::::The schematic I have shows this resistor to be 165 Ohms. I would probably try a standard value resistor as close to this value as possible rated at 5 watts for good measure.
::::::::::
::::::::::Radiodoc
:::::::::
:::::::::
:::::::::
:::::::::::Hi again,
:::::::::::Norm, I have 350 volts at pin 8, but it looks as if you may have called it, Radiodoc. There is a resistor between pin 8 and the orange center tap of the AF Xfmr that is open. I could have sworn I checked that with all the others, but... It appears to be a tubular ceramic type, 1 3/4" long, 7/16" dia marked E33-1336-4. I'm not familiar with these. Any idea of the rating on this?
:::::::::::Steve
:::::::::::
:::::::::::
:::::::::::::Hi Steve
:::::::::::::
::::::::::::: Both tubes, 7AF7 and 7F8, are dual triodes. Either one will work but they are not interchangeable due to base wiring.
:::::::::::::
::::::::::::: You are missing B+ voltage. Check pin #8 on your 5Y3. Should be 300 volts or more. From there it goes to a plug and the speaker field. Check resistance of the field. It may be open?
:::::::::::::
:::::::::::::Norm
::::::::::::
::::::::::::Steve,
::::::::::::
::::::::::::The schematic I have for this radio shows a resistor in the high voltage centertap lead to ground. This could be open. I have had resistors in a similar location in other radios bad.
::::::::::::
::::::::::::Radiodoc
::::::::::::
:::::::::::::
::::::::::::::Hi Norm,
::::::::::::::Thanks for the direction. With positive lead on chassis grnd and negative lead on pins, I read 3 volts each. When touching pin #5 of 6J5 - deafening silence. One note - the schematic here is listed as Code 121. Mine is stamped Code 125 and has a 7AF7 instead of a 7F8.
::::::::::::::Steve
::::::::::::::
:::::::::::::::Hi Steve
:::::::::::::::
::::::::::::::: Measure voltage on pins #3 and #4 of your 6K6 tubes. Both should be positive. These tubes drive your speaker.
:::::::::::::::
::::::::::::::: Measure voltage on pin #3 of your 6J5. This tube drives the 6K6's. Touch pin #5 on your 6J5. You should hear hum.
:::::::::::::::
::::::::::::::: Weak tubes won't stop you from hearing hum in this test, unless they are almost dead.
:::::::::::::::
:::::::::::::::http://www.nostalgiaair.org/PagesByModel/588/M0013588.pdf
:::::::::::::::
:::::::::::::::Norm
:::::::::::::::
:::::::::::::::
::::::::::::::::::Does anyone have tube data for "GT" series tubes? I am working on a Philco 46-1226 which has a 5Y3GT rectifier, a 6J5GT inverter and 6K6GT audio outputs. The roll charts for my 920 do not show these, and I was nervous about just using the 6J5, 6K6 settings. Any help would be appreciated.
:::::::::::::::::
:::::::::::::::::Steve,
:::::::::::::::::
:::::::::::::::::Should work. The 6J5GT and 6K6GT are the glass equivalent of the metal 6J5 and 6K6 respectively.
:::::::::::::::::
:::::::::::::::::Radiodoc
:::::::::::::::::
::::::::::::::::
::::::::::::::::Thanks, Radiodoc. I wasn't sure if they were the same or not. They tested as they should, but tested weak. Now the real question!!!! I have recapped the radio, checked all the IF's, the output xfmr, leads to speaker, speaker, etc, etc, and I can't get even a whisper of sound. Shouldn't I get a little bit of something at least - even if the tubes are weak?
::::::::::::
::::::::::::
::::::::::Steve,
::::::::::
:::::::::

Hi radiodoc,
Well, it actually looks pretty close with the 1000 ohm in place. From the resistor/CT connection to chassis grnd I have 231 volts. Across R30 I have 19V, and on pin 5 I have -18V. I experimented with parallel 1000 ohm resistors and got 277V at the CT and -21V at pin 5. I don't believe it makes a difference, but my set uses 6K6's. My schematic shows no voltages. It shows a "Code 121" while my chassis shows "Code 125", and yours appears to be different yet. How many incarnations do think there were of this set?
Steve

::Radiodoc,
::Schematic shows field coil at 650 ohms. I could get a little closer. If the heat is not an issue then I'm not worried about it. Just wanted to make sure.
::Steve
::
:
:Hi Steve,
:
:You could parallel a couple of your 1000 Ohm resistors and tag them in there. This should give you approximately 500 Ohms. Check the voltage on the side of this resistor going to the CT of the output transformer and see if it is fairly close to what the schematic says. I believe my schematic shows arount plus 240 volts. Something else to check is to measure the voltage across R30. This is the bias voltage for the 6V6s. My print shows a minus 15 volts or so. Also measure the minus voltage on each pin 5 of the 6V6s and should be around minus 11 volts to minus 15 volts. I guesstimate the total current from the power supply to be around 90 milliamps. I was a little high on the value of the resistor to replace the field coil. Sorry about that. Even so a 500 Ohm resistor will get quite hot so make sure it is not too close to wire insulation and other components.
:
:Radiodoc
:
::
::::Well hello again,
::::I have one last question - I hope. Everything seems to be working great here. The only concern I have is that the 1K resistor I installed gets VERY hot. I bumped it up to 25 watts, but it still cooks. It is a ceramic block type. Is there another type that would run cooler, or should I try another value?
::::Thanks for your help,
::::Steve
::::
:::Steve,
:::
:::Generally I would use a resistor somewhere around the value of the field coil resistance is it's resistance is known or shown on the schematic. However, sometimes I experiment with values up or down until I get close to what the plus voltage is according to that on the schematic. May have to trace it around to a plate and/or screen voltage on the output audio tube or tubes. I'll look at the schematic again this weekend and study it again. The resistor will get quite hot as there is a good bit of current through it.
:::
:::Radiodoc
:::
::::
::::
::::
::::
::::::Radiodoc,
::::::It's alive!! I replaced the resistor and all works great. No static, no hum, loud and clear. Thanks again for all your help. It's really great having a site like this and folks like you willing to help.
::::::Steve K
::::::
:::::Steve,
:::::
:::::That's great. It's a nice feeling to when you get an oldtimer working again. You may be getting the bug. Best wishes and be careful when measuring voltages in these old ones.
:::::
:::::Radiodoc
:::::
::::::::Hi again Radiodoc,
::::::::Yes, it is a PM speaker. I had known that but my pea brain couldn't put it together (can't tell I'm a novice, can ya.) If you can stand one last question - what may have caused the resistor to blow in the first place and/or what should I be watching for as I power it up again?
::::::::Steve
::::::::
:::::::
:::::::Hi Steve,
:::::::
:::::::The resistor could have just failed after a period of years. A leaky cap. The wattage rating may have been too small. If you don't have a variac to slowly bring up the line voltage you can make a limiter using a lamp socket and extension cord. Just cut the hot lead and splice the lamp socket in. I use an incandesent lamp of about 50 or 60 watts in the socket. I plug the radio into the socket on the cord and plug the other end into the wall socket. If there is a serious problem the lamp will burn brightly otherwise it will probably light dimly. We all were novices at one time in one thing or another. I am very pleased that many younger persons have decided to try their hand at preserving the history of radio. Just be careful making measurements of voltages in this high voltage tube equipment. I use the one-hand-behind-my-back making measurements for safety.
:::::::
:::::::Radiodoc
:::::::
:::::::
::::::::::Radiodoc,
::::::::::As I rechecked my schematic, I realized we were talking about two different resistors. The schematic I am using is from this site. It shows a 170 ohm resistor from T6 (green) to grnd. This one is fine. The open resistor on my chassis differs from my schematic in that it goes directly from pin #8 on the rectifier to the orange center tap of AF output T5. From this point it goes to C37+. It also has a 10K for R31 plus a 1200ohm from C37+ to C36/25mf+. C37, by the way, is dual electrolytic, 10mf & 25mf paralleled. The only wires to the speaker are the green and black from T5. Is your schematic closer to this? Any ideas?
::::::::::Steve
::::::::::
:::::::::
:::::::::Hi Steve,
:::::::::
:::::::::Has this radio had the dynamic speaker replaced with a PM (permanent magnet)? If I read your description right about a resistor from the rectifier to the output transformer center tap, then this resistor would be across what is/was the speaker field coil. If the speaker has been replaced with a PM type speaker then this resistor would take the place of of the old speaker field coil. Probably could get by with a 1000 ohm 10 watt resistor.
:::::::::
:::::::::Radiodoc
:::::::::
:::::::::
:::::::::::The schematic I have shows this resistor to be 165 Ohms. I would probably try a standard value resistor as close to this value as possible rated at 5 watts for good measure.
:::::::::::
:::::::::::Radiodoc
::::::::::
::::::::::
::::::::::
::::::::::::Hi again,
::::::::::::Norm, I have 350 volts at pin 8, but it looks as if you may have called it, Radiodoc. There is a resistor between pin 8 and the orange center tap of the AF Xfmr that is open. I could have sworn I checked that with all the others, but... It appears to be a tubular ceramic type, 1 3/4" long, 7/16" dia marked E33-1336-4. I'm not familiar with these. Any idea of the rating on this?
::::::::::::Steve
::::::::::::
::::::::::::
::::::::::::::Hi Steve
::::::::::::::
:::::::::::::: Both tubes, 7AF7 and 7F8, are dual triodes. Either one will work but they are not interchangeable due to base wiring.
::::::::::::::
:::::::::::::: You are missing B+ voltage. Check pin #8 on your 5Y3. Should be 300 volts or more. From there it goes to a plug and the speaker field. Check resistance of the field. It may be open?
::::::::::::::
::::::::::::::Norm
:::::::::::::
:::::::::::::Steve,
:::::::::::::
:::::::::::::The schematic I have for this radio shows a resistor in the high voltage centertap lead to ground. This could be open. I have had resistors in a similar location in other radios bad.
:::::::::::::
:::::::::::::Radiodoc
:::::::::::::
::::::::::::::
:::::::::::::::Hi Norm,
:::::::::::::::Thanks for the direction. With positive lead on chassis grnd and negative lead on pins, I read 3 volts each. When touching pin #5 of 6J5 - deafening silence. One note - the schematic here is listed as Code 121. Mine is stamped Code 125 and has a 7AF7 instead of a 7F8.
:::::::::::::::Steve
:::::::::::::::
::::::::::::::::Hi Steve
::::::::::::::::
:::::::::::::::: Measure voltage on pins #3 and #4 of your 6K6 tubes. Both should be positive. These tubes drive your speaker.
::::::::::::::::
:::::::::::::::: Measure voltage on pin #3 of your 6J5. This tube drives the 6K6's. Touch pin #5 on your 6J5. You should hear hum.
::::::::::::::::
:::::::::::::::: Weak tubes won't stop you from hearing hum in this test, unless they are almost dead.
::::::::::::::::
::::::::::::::::http://www.nostalgiaair.org/PagesByModel/588/M0013588.pdf
::::::::::::::::
::::::::::::::::Norm
::::::::::::::::
::::::::::::::::
:::::::::::::::::::Does anyone have tube data for "GT" series tubes? I am working on a Philco 46-1226 which has a 5Y3GT rectifier, a 6J5GT inverter and 6K6GT audio outputs. The roll charts for my 920 do not show these, and I was nervous about just using the 6J5, 6K6 settings. Any help would be appreciated.
::::::::::::::::::
::::::::::::::::::Steve,
::::::::::::::::::
::::::::::::::::::Should work. The 6J5GT and 6K6GT are the glass equivalent of the metal 6J5 and 6K6 respectively.
::::::::::::::::::
::::::::::::::::::Radiodoc
::::::::::::::::::
:::::::::::::::::
:::::::::::::::::Thanks, Radiodoc. I wasn't sure if they were the same or not. They tested as they should, but tested weak. Now the real question!!!! I have recapped the radio, checked all the IF's, the output xfmr, leads to speaker, speaker, etc, etc, and I can't get even a whisper of sound. Shouldn't I get a little bit of something at least - even if the tubes are weak?
:::::::::::::
:::::::::::::
:::::::::::Steve,
:::::::::::
::::::::::

:Hi radiodoc,
:Well, it actually looks pretty close with the 1000 ohm in place. From the resistor/CT connection to chassis grnd I have 231 volts. Across R30 I have 19V, and on pin 5 I have -18V. I experimented with parallel 1000 ohm resistors and got 277V at the CT and -21V at pin 5. I don't believe it makes a difference, but my set uses 6K6's. My schematic shows no voltages. It shows a "Code 121" while my chassis shows "Code 125", and yours appears to be different yet. How many incarnations do think there were of this set?
:Steve

Steve,

Hi Steve,

I don't know how many there could have been. I have a feeling I have somewhere some information on what changes Philco would make that would change the code number. I believe your radio will be ok. If the R30 resistor is not getting hot, then everything will probably be ok. When the radio was made the line voltage was around 110 to 117 volts and today the average line voltage is around 121. Higher line voltage will cause higher power supply voltages.

Radiodoc

:
:::Radiodoc,
:::Schematic shows field coil at 650 ohms. I could get a little closer. If the heat is not an issue then I'm not worried about it. Just wanted to make sure.
:::Steve
:::
::
::Hi Steve,
::
::You could parallel a couple of your 1000 Ohm resistors and tag them in there. This should give you approximately 500 Ohms. Check the voltage on the side of this resistor going to the CT of the output transformer and see if it is fairly close to what the schematic says. I believe my schematic shows arount plus 240 volts. Something else to check is to measure the voltage across R30. This is the bias voltage for the 6V6s. My print shows a minus 15 volts or so. Also measure the minus voltage on each pin 5 of the 6V6s and should be around minus 11 volts to minus 15 volts. I guesstimate the total current from the power supply to be around 90 milliamps. I was a little high on the value of the resistor to replace the field coil. Sorry about that. Even so a 500 Ohm resistor will get quite hot so make sure it is not too close to wire insulation and other components.
::
::Radiodoc
::
:::
:::::Well hello again,
:::::I have one last question - I hope. Everything seems to be working great here. The only concern I have is that the 1K resistor I installed gets VERY hot. I bumped it up to 25 watts, but it still cooks. It is a ceramic block type. Is there another type that would run cooler, or should I try another value?
:::::Thanks for your help,
:::::Steve
:::::
::::Steve,
::::
::::Generally I would use a resistor somewhere around the value of the field coil resistance is it's resistance is known or shown on the schematic. However, sometimes I experiment with values up or down until I get close to what the plus voltage is according to that on the schematic. May have to trace it around to a plate and/or screen voltage on the output audio tube or tubes. I'll look at the schematic again this weekend and study it again. The resistor will get quite hot as there is a good bit of current through it.
::::
::::Radiodoc
::::
:::::
:::::
:::::
:::::
:::::::Radiodoc,
:::::::It's alive!! I replaced the resistor and all works great. No static, no hum, loud and clear. Thanks again for all your help. It's really great having a site like this and folks like you willing to help.
:::::::Steve K
:::::::
::::::Steve,
::::::
::::::That's great. It's a nice feeling to when you get an oldtimer working again. You may be getting the bug. Best wishes and be careful when measuring voltages in these old ones.
::::::
::::::Radiodoc
::::::
:::::::::Hi again Radiodoc,
:::::::::Yes, it is a PM speaker. I had known that but my pea brain couldn't put it together (can't tell I'm a novice, can ya.) If you can stand one last question - what may have caused the resistor to blow in the first place and/or what should I be watching for as I power it up again?
:::::::::Steve
:::::::::
::::::::
::::::::Hi Steve,
::::::::
::::::::The resistor could have just failed after a period of years. A leaky cap. The wattage rating may have been too small. If you don't have a variac to slowly bring up the line voltage you can make a limiter using a lamp socket and extension cord. Just cut the hot lead and splice the lamp socket in. I use an incandesent lamp of about 50 or 60 watts in the socket. I plug the radio into the socket on the cord and plug the other end into the wall socket. If there is a serious problem the lamp will burn brightly otherwise it will probably light dimly. We all were novices at one time in one thing or another. I am very pleased that many younger persons have decided to try their hand at preserving the history of radio. Just be careful making measurements of voltages in this high voltage tube equipment. I use the one-hand-behind-my-back making measurements for safety.
::::::::
::::::::Radiodoc
::::::::
::::::::
:::::::::::Radiodoc,
:::::::::::As I rechecked my schematic, I realized we were talking about two different resistors. The schematic I am using is from this site. It shows a 170 ohm resistor from T6 (green) to grnd. This one is fine. The open resistor on my chassis differs from my schematic in that it goes directly from pin #8 on the rectifier to the orange center tap of AF output T5. From this point it goes to C37+. It also has a 10K for R31 plus a 1200ohm from C37+ to C36/25mf+. C37, by the way, is dual electrolytic, 10mf & 25mf paralleled. The only wires to the speaker are the green and black from T5. Is your schematic closer to this? Any ideas?
:::::::::::Steve
:::::::::::
::::::::::
::::::::::Hi Steve,
::::::::::
::::::::::Has this radio had the dynamic speaker replaced with a PM (permanent magnet)? If I read your description right about a resistor from the rectifier to the output transformer center tap, then this resistor would be across what is/was the speaker field coil. If the speaker has been replaced with a PM type speaker then this resistor would take the place of of the old speaker field coil. Probably could get by with a 1000 ohm 10 watt resistor.
::::::::::
::::::::::Radiodoc
::::::::::
::::::::::
::::::::::::The schematic I have shows this resistor to be 165 Ohms. I would probably try a standard value resistor as close to this value as possible rated at 5 watts for good measure.
::::::::::::
::::::::::::Radiodoc
:::::::::::
:::::::::::
:::::::::::
:::::::::::::Hi again,
:::::::::::::Norm, I have 350 volts at pin 8, but it looks as if you may have called it, Radiodoc. There is a resistor between pin 8 and the orange center tap of the AF Xfmr that is open. I could have sworn I checked that with all the others, but... It appears to be a tubular ceramic type, 1 3/4" long, 7/16" dia marked E33-1336-4. I'm not familiar with these. Any idea of the rating on this?
:::::::::::::Steve
:::::::::::::
:::::::::::::
:::::::::::::::Hi Steve
:::::::::::::::
::::::::::::::: Both tubes, 7AF7 and 7F8, are dual triodes. Either one will work but they are not interchangeable due to base wiring.
:::::::::::::::
::::::::::::::: You are missing B+ voltage. Check pin #8 on your 5Y3. Should be 300 volts or more. From there it goes to a plug and the speaker field. Check resistance of the field. It may be open?
:::::::::::::::
:::::::::::::::Norm
::::::::::::::
::::::::::::::Steve,
::::::::::::::
::::::::::::::The schematic I have for this radio shows a resistor in the high voltage centertap lead to ground. This could be open. I have had resistors in a similar location in other radios bad.
::::::::::::::
::::::::::::::Radiodoc
::::::::::::::
:::::::::::::::
::::::::::::::::Hi Norm,
::::::::::::::::Thanks for the direction. With positive lead on chassis grnd and negative lead on pins, I read 3 volts each. When touching pin #5 of 6J5 - deafening silence. One note - the schematic here is listed as Code 121. Mine is stamped Code 125 and has a 7AF7 instead of a 7F8.
::::::::::::::::Steve
::::::::::::::::
:::::::::::::::::Hi Steve
:::::::::::::::::
::::::::::::::::: Measure voltage on pins #3 and #4 of your 6K6 tubes. Both should be positive. These tubes drive your speaker.
:::::::::::::::::
::::::::::::::::: Measure voltage on pin #3 of your 6J5. This tube drives the 6K6's. Touch pin #5 on your 6J5. You should hear hum.
:::::::::::::::::
::::::::::::::::: Weak tubes won't stop you from hearing hum in this test, unless they are almost dead.
:::::::::::::::::
:::::::::::::::::http://www.nostalgiaair.org/PagesByModel/588/M0013588.pdf
:::::::::::::::::
:::::::::::::::::Norm
:::::::::::::::::
:::::::::::::::::
::::::::::::::::::::Does anyone have tube data for "GT" series tubes? I am working on a Philco 46-1226 which has a 5Y3GT rectifier, a 6J5GT inverter and 6K6GT audio outputs. The roll charts for my 920 do not show these, and I was nervous about just using the 6J5, 6K6 settings. Any help would be appreciated.
:::::::::::::::::::
:::::::::::::::::::Steve,
:::::::::::::::::::
:::::::::::::::::::Should work. The 6J5GT and 6K6GT are the glass equivalent of the metal 6J5 and 6K6 respectively.
:::::::::::::::::::
:::::::::::::::::::Radiodoc
:::::::::::::::::::
::::::::::::::::::
::::::::::::::::::Thanks, Radiodoc. I wasn't sure if they were the same or not. They tested as they should, but tested weak. Now the real question!!!! I have recapped the radio, checked all the IF's, the output xfmr, leads to speaker, speaker, etc, etc, and I can't get even a whisper of sound. Shouldn't I get a little bit of something at least - even if the tubes are weak?
::::::::::::::
::::::::::::::
::::::::::::Steve,
::::::::::::
:::::::::::

Radiodoc,
Thanks again for all your help. It is greatly appreciated!
Steve

::Hi radiodoc,
::Well, it actually looks pretty close with the 1000 ohm in place. From the resistor/CT connection to chassis grnd I have 231 volts. Across R30 I have 19V, and on pin 5 I have -18V. I experimented with parallel 1000 ohm resistors and got 277V at the CT and -21V at pin 5. I don't believe it makes a difference, but my set uses 6K6's. My schematic shows no voltages. It shows a "Code 121" while my chassis shows "Code 125", and yours appears to be different yet. How many incarnations do think there were of this set?
::Steve
:
:Steve,
:
:Hi Steve,
:
:I don't know how many there could have been. I have a feeling I have somewhere some information on what changes Philco would make that would change the code number. I believe your radio will be ok. If the R30 resistor is not getting hot, then everything will probably be ok. When the radio was made the line voltage was around 110 to 117 volts and today the average line voltage is around 121. Higher line voltage will cause higher power supply voltages.
:
:Radiodoc
:
::
::::Radiodoc,
::::Schematic shows field coil at 650 ohms. I could get a little closer. If the heat is not an issue then I'm not worried about it. Just wanted to make sure.
::::Steve
::::
:::
:::Hi Steve,
:::
:::You could parallel a couple of your 1000 Ohm resistors and tag them in there. This should give you approximately 500 Ohms. Check the voltage on the side of this resistor going to the CT of the output transformer and see if it is fairly close to what the schematic says. I believe my schematic shows arount plus 240 volts. Something else to check is to measure the voltage across R30. This is the bias voltage for the 6V6s. My print shows a minus 15 volts or so. Also measure the minus voltage on each pin 5 of the 6V6s and should be around minus 11 volts to minus 15 volts. I guesstimate the total current from the power supply to be around 90 milliamps. I was a little high on the value of the resistor to replace the field coil. Sorry about that. Even so a 500 Ohm resistor will get quite hot so make sure it is not too close to wire insulation and other components.
:::
:::Radiodoc
:::
::::
::::::Well hello again,
::::::I have one last question - I hope. Everything seems to be working great here. The only concern I have is that the 1K resistor I installed gets VERY hot. I bumped it up to 25 watts, but it still cooks. It is a ceramic block type. Is there another type that would run cooler, or should I try another value?
::::::Thanks for your help,
::::::Steve
::::::
:::::Steve,
:::::
:::::Generally I would use a resistor somewhere around the value of the field coil resistance is it's resistance is known or shown on the schematic. However, sometimes I experiment with values up or down until I get close to what the plus voltage is according to that on the schematic. May have to trace it around to a plate and/or screen voltage on the output audio tube or tubes. I'll look at the schematic again this weekend and study it again. The resistor will get quite hot as there is a good bit of current through it.
:::::
:::::Radiodoc
:::::
::::::
::::::
::::::
::::::
::::::::Radiodoc,
::::::::It's alive!! I replaced the resistor and all works great. No static, no hum, loud and clear. Thanks again for all your help. It's really great having a site like this and folks like you willing to help.
::::::::Steve K
::::::::
:::::::Steve,
:::::::
:::::::That's great. It's a nice feeling to when you get an oldtimer working again. You may be getting the bug. Best wishes and be careful when measuring voltages in these old ones.
:::::::
:::::::Radiodoc
:::::::
::::::::::Hi again Radiodoc,
::::::::::Yes, it is a PM speaker. I had known that but my pea brain couldn't put it together (can't tell I'm a novice, can ya.) If you can stand one last question - what may have caused the resistor to blow in the first place and/or what should I be watching for as I power it up again?
::::::::::Steve
::::::::::
:::::::::
:::::::::Hi Steve,
:::::::::
:::::::::The resistor could have just failed after a period of years. A leaky cap. The wattage rating may have been too small. If you don't have a variac to slowly bring up the line voltage you can make a limiter using a lamp socket and extension cord. Just cut the hot lead and splice the lamp socket in. I use an incandesent lamp of about 50 or 60 watts in the socket. I plug the radio into the socket on the cord and plug the other end into the wall socket. If there is a serious problem the lamp will burn brightly otherwise it will probably light dimly. We all were novices at one time in one thing or another. I am very pleased that many younger persons have decided to try their hand at preserving the history of radio. Just be careful making measurements of voltages in this high voltage tube equipment. I use the one-hand-behind-my-back making measurements for safety.
:::::::::
:::::::::Radiodoc
:::::::::
:::::::::
::::::::::::Radiodoc,
::::::::::::As I rechecked my schematic, I realized we were talking about two different resistors. The schematic I am using is from this site. It shows a 170 ohm resistor from T6 (green) to grnd. This one is fine. The open resistor on my chassis differs from my schematic in that it goes directly from pin #8 on the rectifier to the orange center tap of AF output T5. From this point it goes to C37+. It also has a 10K for R31 plus a 1200ohm from C37+ to C36/25mf+. C37, by the way, is dual electrolytic, 10mf & 25mf paralleled. The only wires to the speaker are the green and black from T5. Is your schematic closer to this? Any ideas?
::::::::::::Steve
::::::::::::
:::::::::::
:::::::::::Hi Steve,
:::::::::::
:::::::::::Has this radio had the dynamic speaker replaced with a PM (permanent magnet)? If I read your description right about a resistor from the rectifier to the output transformer center tap, then this resistor would be across what is/was the speaker field coil. If the speaker has been replaced with a PM type speaker then this resistor would take the place of of the old speaker field coil. Probably could get by with a 1000 ohm 10 watt resistor.
:::::::::::
:::::::::::Radiodoc
:::::::::::
:::::::::::
:::::::::::::The schematic I have shows this resistor to be 165 Ohms. I would probably try a standard value resistor as close to this value as possible rated at 5 watts for good measure.
:::::::::::::
:::::::::::::Radiodoc
::::::::::::
::::::::::::
::::::::::::
::::::::::::::Hi again,
::::::::::::::Norm, I have 350 volts at pin 8, but it looks as if you may have called it, Radiodoc. There is a resistor between pin 8 and the orange center tap of the AF Xfmr that is open. I could have sworn I checked that with all the others, but... It appears to be a tubular ceramic type, 1 3/4" long, 7/16" dia marked E33-1336-4. I'm not familiar with these. Any idea of the rating on this?
::::::::::::::Steve
::::::::::::::
::::::::::::::
::::::::::::::::Hi Steve
::::::::::::::::
:::::::::::::::: Both tubes, 7AF7 and 7F8, are dual triodes. Either one will work but they are not interchangeable due to base wiring.
::::::::::::::::
:::::::::::::::: You are missing B+ voltage. Check pin #8 on your 5Y3. Should be 300 volts or more. From there it goes to a plug and the speaker field. Check resistance of the field. It may be open?
::::::::::::::::
::::::::::::::::Norm
:::::::::::::::
:::::::::::::::Steve,
:::::::::::::::
:::::::::::::::The schematic I have for this radio shows a resistor in the high voltage centertap lead to ground. This could be open. I have had resistors in a similar location in other radios bad.
:::::::::::::::
:::::::::::::::Radiodoc
:::::::::::::::
::::::::::::::::
:::::::::::::::::Hi Norm,
:::::::::::::::::Thanks for the direction. With positive lead on chassis grnd and negative lead on pins, I read 3 volts each. When touching pin #5 of 6J5 - deafening silence. One note - the schematic here is listed as Code 121. Mine is stamped Code 125 and has a 7AF7 instead of a 7F8.
:::::::::::::::::Steve
:::::::::::::::::
::::::::::::::::::Hi Steve
::::::::::::::::::
:::::::::::::::::: Measure voltage on pins #3 and #4 of your 6K6 tubes. Both should be positive. These tubes drive your speaker.
::::::::::::::::::
:::::::::::::::::: Measure voltage on pin #3 of your 6J5. This tube drives the 6K6's. Touch pin #5 on your 6J5. You should hear hum.
::::::::::::::::::
:::::::::::::::::: Weak tubes won't stop you from hearing hum in this test, unless they are almost dead.
::::::::::::::::::
::::::::::::::::::http://www.nostalgiaair.org/PagesByModel/588/M0013588.pdf
::::::::::::::::::
::::::::::::::::::Norm
::::::::::::::::::
::::::::::::::::::
:::::::::::::::::::::Does anyone have tube data for "GT" series tubes? I am working on a Philco 46-1226 which has a 5Y3GT rectifier, a 6J5GT inverter and 6K6GT audio outputs. The roll charts for my 920 do not show these, and I was nervous about just using the 6J5, 6K6 settings. Any help would be appreciated.
::::::::::::::::::::
::::::::::::::::::::Steve,
::::::::::::::::::::
::::::::::::::::::::Should work. The 6J5GT and 6K6GT are the glass equivalent of the metal 6J5 and 6K6 respectively.
::::::::::::::::::::
::::::::::::::::::::Radiodoc
::::::::::::::::::::
:::::::::::::::::::
:::::::::::::::::::Thanks, Radiodoc. I wasn't sure if they were the same or not. They tested as they should, but tested weak. Now the real question!!!! I have recapped the radio, checked all the IF's, the output xfmr, leads to speaker, speaker, etc, etc, and I can't get even a whisper of sound. Shouldn't I get a little bit of something at least - even if the tubes are weak?
:::::::::::::::
:::::::::::::::
:::::::::::::Steve,
:::::::::::::
::::::::::::