I have a Philco Model 89 that works good but if I flip a light switch in the room you can hear the click in the speaker like you would om any AM set. The problem is that when you hear the click the raido gets louder and has better tone for a few seconds then it drifts back to the way it was. All the caps have been replaced. Does anyone have any ideas?

Hi

Since your signal gets louder and then fades back down it might be the grid resistor on your 75 tube? Be sure the 10 meg grid resistor hasn't gone higher.

The click from a light switch puts a voltage on the 75 grid. The resistor is supposed to drain the voltage away. If it's very high or open it will take a lot longet to dissipate.

Norm

: I have a Philco Model 89 that works good but if I flip a light switch in the room you can hear the click in the speaker like you would om any AM set. The problem is that when you hear the click the raido gets louder and has better tone for a few seconds then it drifts back to the way it was. All the caps have been replaced. Does anyone have any ideas?

Thanks Norm, I will check that out as soon as I can. If this resistor was to go higher in value, it would drain off the voltage slower, but the radio sounds better (with better tone) and stronger when it has this persumed higher voltage on the grid. So could it be that this resistor value is too low? I'm new to this and I'm trying to learn the logic of trouble shooting. Thank for the help,
Tom

:Hi
:
: Since your signal gets louder and then fades back down it might be the grid resistor on your 75 tube? Be sure the 10 meg grid resistor hasn't gone higher.
:
: The click from a light switch puts a voltage on the 75 grid. The resistor is supposed to drain the voltage away. If it's very high or open it will take a lot longet to dissipate.
:
:Norm
:
:
:
:: I have a Philco Model 89 that works good but if I flip a light switch in the room you can hear the click in the speaker like you would om any AM set. The problem is that when you hear the click the raido gets louder and has better tone for a few seconds then it drifts back to the way it was. All the caps have been replaced. Does anyone have any ideas?

:Hi
:
: Since your signal gets louder and then fades back down it might be the grid resistor on your 75 tube? Be sure the 10 meg grid resistor hasn't gone higher.
:
: The click from a light switch puts a voltage on the 75 grid. The resistor is supposed to drain the voltage away. If it's very high or open it will take a lot longet to dissipate.
:
:Norm
:Norm, The resistor I think you are talking about is 1 meg as listed on the schematic, and it tests very close to that. Any other ideas?
Tom
:
:
:: I have a Philco Model 89 that works good but if I flip a light switch in the room you can hear the click in the speaker like you would om any AM set. The problem is that when you hear the click the raido gets louder and has better tone for a few seconds then it drifts back to the way it was. All the caps have been replaced. Does anyone have any ideas?