Hello everyone,

I changed all of the capacitors in this radio about two years ago and it worked great. I brought it to the table to listen to it and i cannot get any reception except from my florencent lamp which works great with the volume control, good and noisey.

So, thus far, # 44 and 45 filter capacitors measure 380 and 384 VDC using the center tap of the transformer as my most negative point for ground.

The center tap of the # 47 resistor measures 15 VDC, both resistors are within a good tolerance.

With my RF signal tracer i can tune in a station when connected to the grid of the 6A7, nothing on the grid of the 78 and i do get the HUGH hum from the grid of the 75.

I tested the tubes, the 75 is weak but not shorted or leaking.

Is the 15 volts from the center tap of the # 47 resistor too low?

Some ideas are appreciated.

Thank you,

Mitch

Hi MItch

Your explanation is very good. Mentioning picking up florencent lamp noise shows most of the radio is operating.

Check the oscillator circuit. Continuity of the coil shown just to right of the 6A7 and voltage on this tube. Philco coil's open quite often.

http://www.nostalgiaair.org/PagesByModel/793/M0013793.pdf

Norm

:Hello everyone,
:
:I changed all of the capacitors in this radio about two years ago and it worked great. I brought it to the table to listen to it and i cannot get any reception except from my florencent lamp which works great with the volume control, good and noisey.
:
:So, thus far, # 44 and 45 filter capacitors measure 380 and 384 VDC using the center tap of the transformer as my most negative point for ground.
:
:The center tap of the # 47 resistor measures 15 VDC, both resistors are within a good tolerance.
:
:With my RF signal tracer i can tune in a station when connected to the grid of the 6A7, nothing on the grid of the 78 and i do get the HUGH hum from the grid of the 75.
:
:I tested the tubes, the 75 is weak but not shorted or leaking.
:
:Is the 15 volts from the center tap of the # 47 resistor too low?
:
:Some ideas are appreciated.
:
:Thank you,
:
:Mitch
:

:Hello everyone,
:
:I changed all of the capacitors in this radio about two years ago and it worked great. I brought it to the table to listen to it and i cannot get any reception except from my florencent lamp which works great with the volume control, good and noisey.
:
:So, thus far, # 44 and 45 filter capacitors measure 380 and 384 VDC using the center tap of the transformer as my most negative point for ground.
:
:The center tap of the # 47 resistor measures 15 VDC, both resistors are within a good tolerance.
:
:With my RF signal tracer i can tune in a station when connected to the grid of the 6A7, nothing on the grid of the 78 and i do get the HUGH hum from the grid of the 75.
:
:I tested the tubes, the 75 is weak but not shorted or leaking.
:
:Is the 15 volts from the center tap of the # 47 resistor too low?
:
:Some ideas are appreciated.
:
:Thank you,
:
:Mitch

Mitch:
All the fifteen Volts across the resistor does is bias the grids of the audio tubes, and your HUGH hum would indicate that the audio is OK. I kind of suspect: A. trouble in the antenna coil, or B. local oscillator inop. You can check the local oscillator with another radio tuned 460 kHz above the dial setting of the Philco, should hear a sound as you tuen the Philco. Antenna coil can be rung out with an Ohmmeter.
Lewis
:

Reading back I found another bit of good information. You signal generator connected to 6A7 brings in stations. It's being used as the oscillator which is most likely dead.

The osc circuit uses pins 4, 5 and 6 on 6A7 tube.

Norm

::Hello everyone,
::
::I changed all of the capacitors in this radio about two years ago and it worked great. I brought it to the table to listen to it and i cannot get any reception except from my florencent lamp which works great with the volume control, good and noisey.
::
::So, thus far, # 44 and 45 filter capacitors measure 380 and 384 VDC using the center tap of the transformer as my most negative point for ground.
::
::The center tap of the # 47 resistor measures 15 VDC, both resistors are within a good tolerance.
::
::With my RF signal tracer i can tune in a station when connected to the grid of the 6A7, nothing on the grid of the 78 and i do get the HUGH hum from the grid of the 75.
::
::I tested the tubes, the 75 is weak but not shorted or leaking.
::
::Is the 15 volts from the center tap of the # 47 resistor too low?
::
::Some ideas are appreciated.
::
::Thank you,
::
::Mitch
:
:Mitch:
:All the fifteen Volts across the resistor does is bias the grids of the audio tubes, and your HUGH hum would indicate that the audio is OK. I kind of suspect: A. trouble in the antenna coil, or B. local oscillator inop. You can check the local oscillator with another radio tuned 460 kHz above the dial setting of the Philco, should hear a sound as you tuen the Philco. Antenna coil can be rung out with an Ohmmeter.
:Lewis
::
:
:

I remember the oscillator not working before. Looks like the bug has come back again. Your Description indicates a dead oscillator again. The reply from others are good.

:I remember the oscillator not working before. Looks like the bug has come back again. Your Description indicates a dead oscillator again. The reply from others are good.
:
Ok everyone this should tell the story,

6A7, looks like i do not have any negative bias.
Voltages:
Pin 2 = 300 volts
Pin 3 = 38 volts
Pin 4 = 42 volts
Pin 5 = 27 volts
Pin 6 = 21 volts

Where from here?

Thanks for remembering Warren, it was long ago.

Thank you,
Mitch

::I remember the oscillator not working before. Looks like the bug has come back again. Your Description indicates a dead oscillator again. The reply from others are good.
::
:Ok everyone this should tell the story,
:
:6A7, looks like i do not have any negative bias.
:Voltages:
:Pin 2 = 300 volts
:Pin 3 = 38 volts
:Pin 4 = 42 volts
:Pin 5 = 27 volts
:Pin 6 = 21 volts
:
:Where from here?
:
:Thanks for remembering Warren, it was long ago.
:
:Thank you,
:Mitch
:
Forgot to mention that the grid voltage on the 6A7 is a positive 16 VDC.

I will assume that the OSC coil is open, are there any sites that can assist in rebuilding the coil?

Thank you,

Mitch

Measure the coil with ohm meter as per schematic. make sure band switch is good and clean. sometimes moisture is the coil can be cured with hair dryer.

:Measure the coil with ohm meter as per schematic. make sure band switch is good and clean. sometimes moisture is the coil can be cured with hair dryer.
:
I finally got a blow up of the schematic which is very clear.

I do not think I have a bad OSC coil.

I used capacitor # 13 as my end termination for the coil resistance measurements through the coil windings to the pins on the 6A7 tube. Results are:

Pin #4 to #13 = 4 ohms, small coil.
Pin #5 to #13 = 2.7 ohms, large coil.

The band selector switch checks out good. Resistor # 10 and 14 also check good.

I think the OSC coil is good, ideas welcome.

Should i connect my antenna wire directly to the grid of the 6A7? should i now use my signal generator at the antenna to see if i can pass a 455 Kc signal to the speaker?

Thank you,

Mitch

::Measure the coil with ohm meter as per schematic. make sure band switch is good and clean. sometimes moisture is the coil can be cured with hair dryer.
::
:I finally got a blow up of the schematic which is very clear.
:
:I do not think I have a bad OSC coil.
:
:I used capacitor # 13 as my end termination for the coil resistance measurements through the coil windings to the pins on the 6A7 tube. Results are:
:
:Pin #4 to #13 = 4 ohms, small coil.
:Pin #5 to #13 = 2.7 ohms, large coil.
:
:The band selector switch checks out good. Resistor # 10 and 14 also check good.
:
:I think the OSC coil is good, ideas welcome.
:
:Should i connect my antenna wire directly to the grid of the 6A7? should i now use my signal generator at the antenna to see if i can pass a 455 Kc signal to the speaker?
:
:Thank you,
:
:Mitch
:

So, I connected my signal generator at 455 KC to the antenna and received the modulated hum from the speaker when i tuned into it. The sound was strong and i could control it with the volume control. I could also increase/decrease the modulation with the generator.

I am passing a signal through the radio but do not have any station pick up.

Mitch

With the radio will pass the 455KC all the way though without the oscillator working. Remember the transistor radio trick to see if the oscillator is working?

:With the radio will pass the 455KC all the way though without the oscillator working. Remember the transistor radio trick to see if the oscillator is working?
:

You have one great memory of these things.
I turned on a radio and tuned it to a non station next to this Philco, i did not get any signal change from the Philco, no noise or signal buzz or hum as i moved the tuner of the Philco.

Is this how it should be for a dead OSC coil?

It is no problem for me to pull the coil and check it out out of the circuit.

Your memory would take you back to a Crosley with me that had a bad OSC coil, years ago.

Mitch

Mitch

May not be the coil itself since you read continuity. Check the oscillator circuit, cathode, grid #1 and grid #2 make up the osc. Try another tube if you haven't already.

Norm

::With the radio will pass the 455KC all the way though without the oscillator working. Remember the transistor radio trick to see if the oscillator is working?
::
:
:You have one great memory of these things.
:I turned on a radio and tuned it to a non station next to this Philco, i did not get any signal change from the Philco, no noise or signal buzz or hum as i moved the tuner of the Philco.
:
:Is this how it should be for a dead OSC coil?
:
:It is no problem for me to pull the coil and check it out out of the circuit.
:
:Your memory would take you back to a Crosley with me that had a bad OSC coil, years ago.
:
:Mitch
:

Mitch

One other thing. Voltage on your 6A7 aren't right. Pin #6 should be near ground. Check #9, 200 ohm resistor. It may be open?

Norm

::With the radio will pass the 455KC all the way though without the oscillator working. Remember the transistor radio trick to see if the oscillator is working?
::
:
:You have one great memory of these things.
:I turned on a radio and tuned it to a non station next to this Philco, i did not get any signal change from the Philco, no noise or signal buzz or hum as i moved the tuner of the Philco.
:
:Is this how it should be for a dead OSC coil?
:
:It is no problem for me to pull the coil and check it out out of the circuit.
:
:Your memory would take you back to a Crosley with me that had a bad OSC coil, years ago.
:
:Mitch
:

:Mitch
:
: One other thing. Voltage on your 6A7 aren't right. Pin #6 should be near ground. Check #9, 200 ohm resistor. It may be open?
:
:Norm
:
:::With the radio will pass the 455KC all the way though without the oscillator working. Remember the transistor radio trick to see if the oscillator is working?
:::
::
::You have one great memory of these things.
::I turned on a radio and tuned it to a non station next to this Philco, i did not get any signal change from the Philco, no noise or signal buzz or hum as i moved the tuner of the Philco.
::
::Is this how it should be for a dead OSC coil?
::
::It is no problem for me to pull the coil and check it out out of the circuit.
::
::Your memory would take you back to a Crosley with me that had a bad OSC coil, years ago.
::
::Mitch
::
:
:
I appreciate all of the help so far on this radio.

I did change resistors # 19, 14 and 10 just in case there was leakage. I did try another 6A7 and all in all there was no difference in the status of the radio. Resistor #9 measures 197 ohms and is a wire wound fuse resistor.

By all accounts it seems that the OSC is not working even thought it has ohmic measurements. I can pick up floresent light hum, i get the tick, tick sound and the touching of the 75 grid gives a really great hum. Volume control works as well as tone control for the noise. And i can pass a 455 KC modulated signal from the antenna connection to the speaker and control the amplitude of the modulation and sound.

I plan to remove the OSC from the can tonight for inspection, this will be quit a project.

If anyone has any ideas of testing before i start this project let me know, else i shall post results later.

I do not go out on New Year's eve anymore (for many years now) and wish all of you a Happy New Year.

I am glad to be associated with all of you.

Thank you,

Mitch

Mitch

If pin #6 on 6A7 is still high ground it and see what happens. With a 200 ohm cathode resistor expect around 3 volts on this pin.

Norm

::Mitch
::
:: One other thing. Voltage on your 6A7 aren't right. Pin #6 should be near ground. Check #9, 200 ohm resistor. It may be open?
::
::Norm
::
::::With the radio will pass the 455KC all the way though without the oscillator working. Remember the transistor radio trick to see if the oscillator is working?
::::
:::
:::You have one great memory of these things.
:::I turned on a radio and tuned it to a non station next to this Philco, i did not get any signal change from the Philco, no noise or signal buzz or hum as i moved the tuner of the Philco.
:::
:::Is this how it should be for a dead OSC coil?
:::
:::It is no problem for me to pull the coil and check it out out of the circuit.
:::
:::Your memory would take you back to a Crosley with me that had a bad OSC coil, years ago.
:::
:::Mitch
:::
::
::
:I appreciate all of the help so far on this radio.
:
:I did change resistors # 19, 14 and 10 just in case there was leakage. I did try another 6A7 and all in all there was no difference in the status of the radio. Resistor #9 measures 197 ohms and is a wire wound fuse resistor.
:
:By all accounts it seems that the OSC is not working even thought it has ohmic measurements. I can pick up floresent light hum, i get the tick, tick sound and the touching of the 75 grid gives a really great hum. Volume control works as well as tone control for the noise. And i can pass a 455 KC modulated signal from the antenna connection to the speaker and control the amplitude of the modulation and sound.
:
:I plan to remove the OSC from the can tonight for inspection, this will be quit a project.
:
:If anyone has any ideas of testing before i start this project let me know, else i shall post results later.
:
:I do not go out on New Year's eve anymore (for many years now) and wish all of you a Happy New Year.
:
:I am glad to be associated with all of you.
:
:Thank you,
:
:Mitch
:
:
:

:Mitch
:
: If pin #6 on 6A7 is still high ground it and see what happens. With a 200 ohm cathode resistor expect around 3 volts on this pin.
:
:Norm
:
:::Mitch
:::
::: One other thing. Voltage on your 6A7 aren't right. Pin #6 should be near ground. Check #9, 200 ohm resistor. It may be open?
:::
:::Norm
:::
:::::With the radio will pass the 455KC all the way though without the oscillator working. Remember the transistor radio trick to see if the oscillator is working?
:::::
::::
::::You have one great memory of these things.
::::I turned on a radio and tuned it to a non station next to this Philco, i did not get any signal change from the Philco, no noise or signal buzz or hum as i moved the tuner of the Philco.
::::
::::Is this how it should be for a dead OSC coil?
::::
::::It is no problem for me to pull the coil and check it out out of the circuit.
::::
::::Your memory would take you back to a Crosley with me that had a bad OSC coil, years ago.
::::
::::Mitch
::::
:::
:::
::I appreciate all of the help so far on this radio.
::
::I did change resistors # 19, 14 and 10 just in case there was leakage. I did try another 6A7 and all in all there was no difference in the status of the radio. Resistor #9 measures 197 ohms and is a wire wound fuse resistor.
::
::By all accounts it seems that the OSC is not working even thought it has ohmic measurements. I can pick up floresent light hum, i get the tick, tick sound and the touching of the 75 grid gives a really great hum. Volume control works as well as tone control for the noise. And i can pass a 455 KC modulated signal from the antenna connection to the speaker and control the amplitude of the modulation and sound.
::
::I plan to remove the OSC from the can tonight for inspection, this will be quit a project.
::
::If anyone has any ideas of testing before i start this project let me know, else i shall post results later.
::
::I do not go out on New Year's eve anymore (for many years now) and wish all of you a Happy New Year.
::
::I am glad to be associated with all of you.
::
::Thank you,
::
::Mitch
::
::
::
:
:
Hello everyone,

Some results on the OSC coil. The coil is out of the can and looks brand new, perhaps the radio was stored indoors all of it's life.

I will call the left side of the coil with the band switch taps that connects to pin 5 of the 6A7 the primary, the other the secondary.

Resistance measurements are (#13 removed):

Top of coil to first tap = .7 ohms
Across band switch coil connections 2 ohms
Bottom of band switch to end of coil = .6 ohm

Total resistance for the Primary = Appx 3 ohms.

Secondary coil = 4 ohms.

I think the OSC coil is good? Comments welcome on my results for the coil before i reinstall it.

I also plan to replace the # 13 capacitor with a new 100 pf capacitor (should be 110pf, it's what i have in the box).

Now to really pull your experience. I do rebuild IF transformers using a capacitance meter, RF signal generator and 100 MHZ scope. I am an old bench tech.

Now that i have the OSC coil assembly out of the radio and it appears that there is a primary and secondary winding, how can i test this oscillator with signal injection and see an output with my scope to be sure it is working? What i want to see is some result of oscillation and also be sure there are no shorts in the windings under some load..

All responses are welcome.

If the coil can be tested good i can move on to the repair with confidence in this coil.

Thank you,

Mitch

Wonder if the osc section of the tuning cap may be shorted??

Clifton

::Mitch
::
:: If pin #6 on 6A7 is still high ground it and see what happens. With a 200 ohm cathode resistor expect around 3 volts on this pin.
::
::Norm
::
::::Mitch
::::
:::: One other thing. Voltage on your 6A7 aren't right. Pin #6 should be near ground. Check #9, 200 ohm resistor. It may be open?
::::
::::Norm
::::
::::::With the radio will pass the 455KC all the way though without the oscillator working. Remember the transistor radio trick to see if the oscillator is working?
::::::
:::::
:::::You have one great memory of these things.
:::::I turned on a radio and tuned it to a non station next to this Philco, i did not get any signal change from the Philco, no noise or signal buzz or hum as i moved the tuner of the Philco.
:::::
:::::Is this how it should be for a dead OSC coil?
:::::
:::::It is no problem for me to pull the coil and check it out out of the circuit.
:::::
:::::Your memory would take you back to a Crosley with me that had a bad OSC coil, years ago.
:::::
:::::Mitch
:::::
::::
::::
:::I appreciate all of the help so far on this radio.
:::
:::I did change resistors # 19, 14 and 10 just in case there was leakage. I did try another 6A7 and all in all there was no difference in the status of the radio. Resistor #9 measures 197 ohms and is a wire wound fuse resistor.
:::
:::By all accounts it seems that the OSC is not working even thought it has ohmic measurements. I can pick up floresent light hum, i get the tick, tick sound and the touching of the 75 grid gives a really great hum. Volume control works as well as tone control for the noise. And i can pass a 455 KC modulated signal from the antenna connection to the speaker and control the amplitude of the modulation and sound.
:::
:::I plan to remove the OSC from the can tonight for inspection, this will be quit a project.
:::
:::If anyone has any ideas of testing before i start this project let me know, else i shall post results later.
:::
:::I do not go out on New Year's eve anymore (for many years now) and wish all of you a Happy New Year.
:::
:::I am glad to be associated with all of you.
:::
:::Thank you,
:::
:::Mitch
:::
:::
:::
::
::
:Hello everyone,
:
:Some results on the OSC coil. The coil is out of the can and looks brand new, perhaps the radio was stored indoors all of it's life.
:
:I will call the left side of the coil with the band switch taps that connects to pin 5 of the 6A7 the primary, the other the secondary.
:
:Resistance measurements are (#13 removed):
:
:Top of coil to first tap = .7 ohms
:Across band switch coil connections 2 ohms
:Bottom of band switch to end of coil = .6 ohm
:
:Total resistance for the Primary = Appx 3 ohms.
:
:Secondary coil = 4 ohms.
:
:I think the OSC coil is good? Comments welcome on my results for the coil before i reinstall it.
:
:I also plan to replace the # 13 capacitor with a new 100 pf capacitor (should be 110pf, it's what i have in the box).
:
:Now to really pull your experience. I do rebuild IF transformers using a capacitance meter, RF signal generator and 100 MHZ scope. I am an old bench tech.
:
:Now that i have the OSC coil assembly out of the radio and it appears that there is a primary and secondary winding, how can i test this oscillator with signal injection and see an output with my scope to be sure it is working? What i want to see is some result of oscillation and also be sure there are no shorts in the windings under some load..
:
:All responses are welcome.
:
:If the coil can be tested good i can move on to the repair with confidence in this coil.
:
:Thank you,
:
:Mitch
:

:Wonder if the osc section of the tuning cap may be shorted??
:
:Clifton
:
:
:::Mitch
:::
::: If pin #6 on 6A7 is still high ground it and see what happens. With a 200 ohm cathode resistor expect around 3 volts on this pin.
:::
:::Norm
:::
:::::Mitch
:::::
::::: One other thing. Voltage on your 6A7 aren't right. Pin #6 should be near ground. Check #9, 200 ohm resistor. It may be open?
:::::
:::::Norm
:::::
:::::::With the radio will pass the 455KC all the way though without the oscillator working. Remember the transistor radio trick to see if the oscillator is working?
:::::::
::::::
::::::You have one great memory of these things.
::::::I turned on a radio and tuned it to a non station next to this Philco, i did not get any signal change from the Philco, no noise or signal buzz or hum as i moved the tuner of the Philco.
::::::
::::::Is this how it should be for a dead OSC coil?
::::::
::::::It is no problem for me to pull the coil and check it out out of the circuit.
::::::
::::::Your memory would take you back to a Crosley with me that had a bad OSC coil, years ago.
::::::
::::::Mitch
::::::
:::::
:::::
::::I appreciate all of the help so far on this radio.
::::
::::I did change resistors # 19, 14 and 10 just in case there was leakage. I did try another 6A7 and all in all there was no difference in the status of the radio. Resistor #9 measures 197 ohms and is a wire wound fuse resistor.
::::
::::By all accounts it seems that the OSC is not working even thought it has ohmic measurements. I can pick up floresent light hum, i get the tick, tick sound and the touching of the 75 grid gives a really great hum. Volume control works as well as tone control for the noise. And i can pass a 455 KC modulated signal from the antenna connection to the speaker and control the amplitude of the modulation and sound.
::::
::::I plan to remove the OSC from the can tonight for inspection, this will be quit a project.
::::
::::If anyone has any ideas of testing before i start this project let me know, else i shall post results later.
::::
::::I do not go out on New Year's eve anymore (for many years now) and wish all of you a Happy New Year.
::::
::::I am glad to be associated with all of you.
::::
::::Thank you,
::::
::::Mitch
::::
::::
::::
:::
:::
::Hello everyone,
::
::Some results on the OSC coil. The coil is out of the can and looks brand new, perhaps the radio was stored indoors all of it's life.
::
::I will call the left side of the coil with the band switch taps that connects to pin 5 of the 6A7 the primary, the other the secondary.
::
::Resistance measurements are (#13 removed):
::
::Top of coil to first tap = .7 ohms
::Across band switch coil connections 2 ohms
::Bottom of band switch to end of coil = .6 ohm
::
::Total resistance for the Primary = Appx 3 ohms.
::
::Secondary coil = 4 ohms.
::
::I think the OSC coil is good? Comments welcome on my results for the coil before i reinstall it.
::
::I also plan to replace the # 13 capacitor with a new 100 pf capacitor (should be 110pf, it's what i have in the box).
::
::Now to really pull your experience. I do rebuild IF transformers using a capacitance meter, RF signal generator and 100 MHZ scope. I am an old bench tech.
::
::Now that i have the OSC coil assembly out of the radio and it appears that there is a primary and secondary winding, how can i test this oscillator with signal injection and see an output with my scope to be sure it is working? What i want to see is some result of oscillation and also be sure there are no shorts in the windings under some load..
::
::All responses are welcome.
::
::If the coil can be tested good i can move on to the repair with confidence in this coil.
::
::Thank you,
::
::Mitch
::
:
:
Hello everyone,

I am sure we will get it.

The tuner plates are not shorted.

I replaced the OSC coil after extensive testing with a RF generator and a scope to ensure that a modulated signal with some current did pass through from the primary to the secondary coils of the OSC coil.

The result is the same, no stations, but great noise.

I shorted the #6 pin on the 6A7 and the voltage was 16 VDC, way too much.

The voltages on the 6A7 are way to high, I might start pulling capacitor leads in the circuit to see if a short may be the problem.

I know this is a long post, maybe someone out here has a direction for me to follow to get closer to the solution.

Thank you,

Mitch

::Wonder if the osc section of the tuning cap may be shorted??
::
::Clifton
::
::
::::Mitch
::::
:::: If pin #6 on 6A7 is still high ground it and see what happens. With a 200 ohm cathode resistor expect around 3 volts on this pin.
::::
::::Norm
::::
::::::Mitch
::::::
:::::: One other thing. Voltage on your 6A7 aren't right. Pin #6 should be near ground. Check #9, 200 ohm resistor. It may be open?
::::::
::::::Norm
::::::
::::::::With the radio will pass the 455KC all the way though without the oscillator working. Remember the transistor radio trick to see if the oscillator is working?
::::::::
:::::::
:::::::You have one great memory of these things.
:::::::I turned on a radio and tuned it to a non station next to this Philco, i did not get any signal change from the Philco, no noise or signal buzz or hum as i moved the tuner of the Philco.
:::::::
:::::::Is this how it should be for a dead OSC coil?
:::::::
:::::::It is no problem for me to pull the coil and check it out out of the circuit.
:::::::
:::::::Your memory would take you back to a Crosley with me that had a bad OSC coil, years ago.
:::::::
:::::::Mitch
:::::::
::::::
::::::
:::::I appreciate all of the help so far on this radio.
:::::
:::::I did change resistors # 19, 14 and 10 just in case there was leakage. I did try another 6A7 and all in all there was no difference in the status of the radio. Resistor #9 measures 197 ohms and is a wire wound fuse resistor.
:::::
:::::By all accounts it seems that the OSC is not working even thought it has ohmic measurements. I can pick up floresent light hum, i get the tick, tick sound and the touching of the 75 grid gives a really great hum. Volume control works as well as tone control for the noise. And i can pass a 455 KC modulated signal from the antenna connection to the speaker and control the amplitude of the modulation and sound.
:::::
:::::I plan to remove the OSC from the can tonight for inspection, this will be quit a project.
:::::
:::::If anyone has any ideas of testing before i start this project let me know, else i shall post results later.
:::::
:::::I do not go out on New Year's eve anymore (for many years now) and wish all of you a Happy New Year.
:::::
:::::I am glad to be associated with all of you.
:::::
:::::Thank you,
:::::
:::::Mitch
:::::
:::::
:::::
::::
::::
:::Hello everyone,
:::
:::Some results on the OSC coil. The coil is out of the can and looks brand new, perhaps the radio was stored indoors all of it's life.
:::
:::I will call the left side of the coil with the band switch taps that connects to pin 5 of the 6A7 the primary, the other the secondary.
:::
:::Resistance measurements are (#13 removed):
:::
:::Top of coil to first tap = .7 ohms
:::Across band switch coil connections 2 ohms
:::Bottom of band switch to end of coil = .6 ohm
:::
:::Total resistance for the Primary = Appx 3 ohms.
:::
:::Secondary coil = 4 ohms.
:::
:::I think the OSC coil is good? Comments welcome on my results for the coil before i reinstall it.
:::
:::I also plan to replace the # 13 capacitor with a new 100 pf capacitor (should be 110pf, it's what i have in the box).
:::
:::Now to really pull your experience. I do rebuild IF transformers using a capacitance meter, RF signal generator and 100 MHZ scope. I am an old bench tech.
:::
:::Now that i have the OSC coil assembly out of the radio and it appears that there is a primary and secondary winding, how can i test this oscillator with signal injection and see an output with my scope to be sure it is working? What i want to see is some result of oscillation and also be sure there are no shorts in the windings under some load..
:::
:::All responses are welcome.
:::
:::If the coil can be tested good i can move on to the repair with confidence in this coil.
:::
:::Thank you,
:::
:::Mitch
:::
::
::
:Hello everyone,
:
:I am sure we will get it.
:
:The tuner plates are not shorted.
:
:I replaced the OSC coil after extensive testing with a RF generator and a scope to ensure that a modulated signal with some current did pass through from the primary to the secondary coils of the OSC coil.
:
:The result is the same, no stations, but great noise.
:
:I shorted the #6 pin on the 6A7 and the voltage was 16 VDC, way too much.
:
:The voltages on the 6A7 are way to high, I might start pulling capacitor leads in the circuit to see if a short may be the problem.
:
:I know this is a long post, maybe someone out here has a direction for me to follow to get closer to the solution.
:
:Thank you,
:
:Mitch
:

I have a RF signal tracer connected to the grid of the 6A7, with my wire antenna connected i can dial in several stations and listen to them from the speaker of the RF tracer, nothing from the radio speaker, just good noise.

The OSC coil is not bad, in the operation of the tube what would cause the #6 cathode to be at 21 VDC?

Could it be capacitor # 6,or 12?

Mitch

:::Wonder if the osc section of the tuning cap may be shorted??
:::
:::Clifton
:::
:::
:::::Mitch
:::::
::::: If pin #6 on 6A7 is still high ground it and see what happens. With a 200 ohm cathode resistor expect around 3 volts on this pin.
:::::
:::::Norm
:::::
:::::::Mitch
:::::::
::::::: One other thing. Voltage on your 6A7 aren't right. Pin #6 should be near ground. Check #9, 200 ohm resistor. It may be open?
:::::::
:::::::Norm
:::::::
:::::::::With the radio will pass the 455KC all the way though without the oscillator working. Remember the transistor radio trick to see if the oscillator is working?
:::::::::
::::::::
::::::::You have one great memory of these things.
::::::::I turned on a radio and tuned it to a non station next to this Philco, i did not get any signal change from the Philco, no noise or signal buzz or hum as i moved the tuner of the Philco.
::::::::
::::::::Is this how it should be for a dead OSC coil?
::::::::
::::::::It is no problem for me to pull the coil and check it out out of the circuit.
::::::::
::::::::Your memory would take you back to a Crosley with me that had a bad OSC coil, years ago.
::::::::
::::::::Mitch
::::::::
:::::::
:::::::
::::::I appreciate all of the help so far on this radio.
::::::
::::::I did change resistors # 19, 14 and 10 just in case there was leakage. I did try another 6A7 and all in all there was no difference in the status of the radio. Resistor #9 measures 197 ohms and is a wire wound fuse resistor.
::::::
::::::By all accounts it seems that the OSC is not working even thought it has ohmic measurements. I can pick up floresent light hum, i get the tick, tick sound and the touching of the 75 grid gives a really great hum. Volume control works as well as tone control for the noise. And i can pass a 455 KC modulated signal from the antenna connection to the speaker and control the amplitude of the modulation and sound.
::::::
::::::I plan to remove the OSC from the can tonight for inspection, this will be quit a project.
::::::
::::::If anyone has any ideas of testing before i start this project let me know, else i shall post results later.
::::::
::::::I do not go out on New Year's eve anymore (for many years now) and wish all of you a Happy New Year.
::::::
::::::I am glad to be associated with all of you.
::::::
::::::Thank you,
::::::
::::::Mitch
::::::
::::::
::::::
:::::
:::::
::::Hello everyone,
::::
::::Some results on the OSC coil. The coil is out of the can and looks brand new, perhaps the radio was stored indoors all of it's life.
::::
::::I will call the left side of the coil with the band switch taps that connects to pin 5 of the 6A7 the primary, the other the secondary.
::::
::::Resistance measurements are (#13 removed):
::::
::::Top of coil to first tap = .7 ohms
::::Across band switch coil connections 2 ohms
::::Bottom of band switch to end of coil = .6 ohm
::::
::::Total resistance for the Primary = Appx 3 ohms.
::::
::::Secondary coil = 4 ohms.
::::
::::I think the OSC coil is good? Comments welcome on my results for the coil before i reinstall it.
::::
::::I also plan to replace the # 13 capacitor with a new 100 pf capacitor (should be 110pf, it's what i have in the box).
::::
::::Now to really pull your experience. I do rebuild IF transformers using a capacitance meter, RF signal generator and 100 MHZ scope. I am an old bench tech.
::::
::::Now that i have the OSC coil assembly out of the radio and it appears that there is a primary and secondary winding, how can i test this oscillator with signal injection and see an output with my scope to be sure it is working? What i want to see is some result of oscillation and also be sure there are no shorts in the windings under some load..
::::
::::All responses are welcome.
::::
::::If the coil can be tested good i can move on to the repair with confidence in this coil.
::::
::::Thank you,
::::
::::Mitch
::::
:::
:::
::Hello everyone,
::
::I am sure we will get it.
::
::The tuner plates are not shorted.
::
::I replaced the OSC coil after extensive testing with a RF generator and a scope to ensure that a modulated signal with some current did pass through from the primary to the secondary coils of the OSC coil.
::
::The result is the same, no stations, but great noise.
::
::I shorted the #6 pin on the 6A7 and the voltage was 16 VDC, way too much.
::
::The voltages on the 6A7 are way to high, I might start pulling capacitor leads in the circuit to see if a short may be the problem.
::
::I know this is a long post, maybe someone out here has a direction for me to follow to get closer to the solution.
::
::Thank you,
::
::Mitch
::
:
:I have a RF signal tracer connected to the grid of the 6A7, with my wire antenna connected i can dial in several stations and listen to them from the speaker of the RF tracer, nothing from the radio speaker, just good noise.
:
:The OSC coil is not bad, in the operation of the tube what would cause the #6 cathode to be at 21 VDC?
:
:Could it be capacitor # 6,or 12?
(I 'soitanly wouldn't suspect them . . . . . Edd)
:
:Mitch

Sir Mitch. . . . As per your . . . The OSC coil is not bad, in the operation of the tube what would cause the #6 cathode to be at 21 VDC? If that pin is being the "commode" of the 6A7 . . . . then the "commode" of the 78 is also getting into the act, since they are both sharing that common 200 ohm resistor (is it testing as 200 ohms . . not 2K ? right ? ) That would be indicative of the tube pair pulling a quite hefty current thru the resistor. ANALYTICAL PROCEDURE #1: With that signal tracer being on the top cap of your 6A7, you were merely having yourself a glorified xtal set. Instead, move that signal tracer probe over to the Plate of the 6A7 and then be expecting the IF's resonating L/C pair to then be selecting out the IF signal, and IF there is local oscillator presence, as you now tune from end to end of the dial scale; you should hear separated stations if all is well in that mixer stage. (Loooong wire aerial connected.) ANALYTICAL PROCEDURE #2: Your grid resistor for the osc stage is resistor item 10 So set metering instrumentation to its DC voltage mode and measure across it with your metering negative connection being the left (cathode connected ) end of that resistor. Expect a developed NEGATIVE DC voltage to be developed on the RIGHT side of that resistor (its 1st grid side via the series osc coil inductance) in accordance to how active the oscillator action is and whether you are being at the high end of the BCB or the low end. If using a VTVM . . . . . and I dont know its degree of AC line isolation presented. . . as some use a "static" 1 meg resistor from AC line to instrument ground . . . that's bad. You might pull out your totally isolated battery powered DVM to take measurements with, as their input impedance is also affording a HIGH Zeeeee loading factor. If you are now reading your developed oscillator negative grid voltage, stop ye olde tuning condensateur so that its being half meshed. Then you spittle moisten an index finger and touch at the apex of the stator/ rotor meshing of the OSCILLATOR section of the tuning condenser. That oscillator developed voltage should drop off during that action, but return as soon as you take your finger (RF short / detuning)away. (UNLESS you left a residual spittle spider web bridge between plates.) Thassitt . . . . Whaaaaaassssssssuuuuuup now ?. 73's de Edd WOW . . . . . . . (Timely Tip:) NEVER EVER attempt to fasten your shoe laces while inside a revolving supermarket door.