05-28-2026, 02:49 PM
Mike,
This one shows -1.7V presently. When I tested it before, it showed -0.4V. This is one of those values marked with an asterisk to say that it can't be accurately measured because of the loading from the meter, but unlike the others, it doesn't show a value for what a meter so connected should read, even if not the true value.
Interestingly, for some reason, right now, without changing any components out, but simply it seems as a result of tuning back and forth and adjusting the volume, the voltage at the R14/15 junction has increased up to approximately 182V. Consequently, my screen grids at 6A8 and 6K7 are now testing at around 90V. Obviously, this gets the screen grids closer, but would this have an adverse impact on C16 or oscillator coil? There's also a connection to the socket of the 6F5, but there's no pin on that position, so I suspect the 6F5 wouldn't care. Not even sure why there's a connection to that pin all by itself.
The rest of the voltages throughout the other tubes seem to be closer to what is specified than they were when tested before, a couple weeks ago, though they weren't very far off to begin with.
I know there is some noise when adjusting the volume, so I'm wondering if some imperfection here might be sabotaging the testing. Even though the 6A8 and 6K7 are in the RF section, the volume and tone controls do have a pretty direct connection to the start (R14) of the voltage dividing resistor - could these be affecting the voltage going into it?
I have some Deoxit D5 and F5 arriving soon. I've seen F5 recommended for volume pots. Maybe trying to clean that up will make a difference.
Best wishes,
Roy
This one shows -1.7V presently. When I tested it before, it showed -0.4V. This is one of those values marked with an asterisk to say that it can't be accurately measured because of the loading from the meter, but unlike the others, it doesn't show a value for what a meter so connected should read, even if not the true value.
Interestingly, for some reason, right now, without changing any components out, but simply it seems as a result of tuning back and forth and adjusting the volume, the voltage at the R14/15 junction has increased up to approximately 182V. Consequently, my screen grids at 6A8 and 6K7 are now testing at around 90V. Obviously, this gets the screen grids closer, but would this have an adverse impact on C16 or oscillator coil? There's also a connection to the socket of the 6F5, but there's no pin on that position, so I suspect the 6F5 wouldn't care. Not even sure why there's a connection to that pin all by itself.
The rest of the voltages throughout the other tubes seem to be closer to what is specified than they were when tested before, a couple weeks ago, though they weren't very far off to begin with.
I know there is some noise when adjusting the volume, so I'm wondering if some imperfection here might be sabotaging the testing. Even though the 6A8 and 6K7 are in the RF section, the volume and tone controls do have a pretty direct connection to the start (R14) of the voltage dividing resistor - could these be affecting the voltage going into it?
I have some Deoxit D5 and F5 arriving soon. I've seen F5 recommended for volume pots. Maybe trying to clean that up will make a difference.
Best wishes,
Roy




