Hello All, I have been in the process of restoring the chassis of this model. I have replaced all paper and electolytic capacitors. Everything works fine with the exception of the antenna circut. After a few minutes of operation I loose some output. When the antenna is disconnected and re-connected I gain back the output. This keeps happening. Also if I touch the grid of the 78 tube this will restore the output. Does anyone have any suggestions. Thank You

Make sure that your AVC resistors have not drifted, and make sure that the AVC buffer condenser (.05 mfd) that connects from the bottom of the antenna secondary (bottom as shown on diagram) to B- is not leaky at all. Usually if this is leaky, though, the music will be louder. More likely drifted resistors.

Thomas

:Hello All, I have been in the process of restoring the chassis of this model. I have replaced all paper and electolytic capacitors. Everything works fine with the exception of the antenna circut. After a few minutes of operation I loose some output. When the antenna is disconnected and re-connected I gain back the output. This keeps happening. Also if I touch the grid of the 78 tube this will restore the output. Does anyone have any suggestions. Thank You

:Make sure that your AVC resistors have not drifted, and make sure that the AVC buffer condenser (.05 mfd) that connects from the bottom of the antenna secondary (bottom as shown on diagram) to B- is not leaky at all. Usually if this is leaky, though, the music will be louder. More likely drifted resistors.
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:Thomas
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::Hello All, I have been in the process of restoring the chassis of this model. I have replaced all paper and electolytic capacitors. Everything works fine with the exception of the antenna circut. After a few minutes of operation I loose some output. When the antenna is disconnected and re-connected I gain back the output. This keeps happening. Also if I touch the grid of the 78 tube this will restore the output. Does anyone have any suggestions. Thank You

::Make sure that your AVC resistors have not drifted, and make sure that the AVC buffer condenser (.05 mfd) that connects from the bottom of the antenna secondary (bottom as shown on diagram) to B- is not leaky at all. Usually if this is leaky, though, the music will be louder. More likely drifted resistors.
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::Thomas
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Thanks for the help Thomas, I will double check all resistors. I found one resistor in the AVC circut that had increased in value by 80%. By replacing this I eliminated overload distortion. The only resistors and capacitors that I have not checked are inside the 2nd IF can.
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:::Hello All, I have been in the process of restoring the chassis of this model. I have replaced all paper and electolytic capacitors. Everything works fine with the exception of the antenna circut. After a few minutes of operation I loose some output. When the antenna is disconnected and re-connected I gain back the output. This keeps happening. Also if I touch the grid of the 78 tube this will restore the output. Does anyone have any suggestions. Thank You

You're welcome! The resistors and capacitors inside the second IF can don't usually have much affect on anything if they drift, though they can. The capacitors serve to remove some of the very high frequencies to smooth out the audio, and passing the audio through the resistors accomplishes the same.

Occasionally the capacitors can short. If they open up, you may not notice the small amount of additional high audio that they normally cut off. The resistors, as they drift higher, will cause the set to be a little more bassy, and eventually will make it get quieter. Resistors, as they get higher in value, pass bass more easily than treble notes.

Good luck and enjoy,

Thomas
:::Make sure that your AVC resistors have not drifted, and make sure that the AVC buffer condenser (.05 mfd) that connects from the bottom of the antenna secondary (bottom as shown on diagram) to B- is not leaky at all. Usually if this is leaky, though, the music will be louder. More likely drifted resistors.
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:::Thomas
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:Thanks for the help Thomas, I will double check all resistors. I found one resistor in the AVC circut that had increased in value by 80%. By replacing this I eliminated overload distortion. The only resistors and capacitors that I have not checked are inside the 2nd IF can.
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::::Hello All, I have been in the process of restoring the chassis of this model. I have replaced all paper and electolytic capacitors. Everything works fine with the exception of the antenna circut. After a few minutes of operation I loose some output. When the antenna is disconnected and re-connected I gain back the output. This keeps happening. Also if I touch the grid of the 78 tube this will restore the output. Does anyone have any suggestions. Thank You

:Hello All, I have been in the process of restoring the chassis of this model. I have replaced all paper and electolytic capacitors. Everything works fine with the exception of the antenna circut. After a few minutes of operation I loose some output. When the antenna is disconnected and re-connected I gain back the output. This keeps happening. Also if I touch the grid of the 78 tube this will restore the output. Does anyone have any suggestions. Thank You

Dear Uncle Paul:
Have you tried to replace the feeder to the antenna? Also does the circuit AT the antenna get warm or hot?
You might just have a thin wire going from the circuit board to the antenna

You’re Nephew Cory

Where do these weird people come from? Too many kids with too little to do!

T.

:Dear Uncle Paul:
:Have you tried to replace the feeder to the antenna? Also does the circuit AT the antenna get warm or hot?
:You might just have a thin wire going from the circuit board to the antenna
:
:You’re Nephew Cory
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