11-30-2011, 04:36 PM
I do have feedback when I touch the top of the 6r7 and I went one step further, the 1 meg resistor in the tube cap circuit that wnet nowhere, well it should go to resistor #111, I did that and my pin #3 voltage on the 6r7 went from 45 volts to 89 volts(spec is 70v) and it did not kill the static like before. Should I be concerned now that the voltage is 10 - 20 volts higher everywhere if the negative bias is pretty much at spec?
I'm not too concerned about that. Keep in mind that the line voltage is a bit higher than it was back in '38. If it bugs you just go down the string of resistors that feed the b+ to the 6R7 till you find the one that has drifted high in resistance and that is going to fix that problem.
If you want to give the audio stages a test you can connect an audio source to the grid cap of the 6R7and chassis ground. At that point there is no volume control so keep your source level down low lest it will blast you out of the room.
Something else to have a look at is there is a muting switch that is triggered when you push in the arm that is next to the tuning knob. Double check that it's isn't muting the audio from the detector.
On the 20 ohm resistor I'd put a new one in at some point mark it down for replacement and order a new one with a high wattage rating.
Terry
You might think I'm smart but not really, I've got a 37-116 that I fixed up back in the '80's. It need a good going over again.
I'm not too concerned about that. Keep in mind that the line voltage is a bit higher than it was back in '38. If it bugs you just go down the string of resistors that feed the b+ to the 6R7 till you find the one that has drifted high in resistance and that is going to fix that problem.
If you want to give the audio stages a test you can connect an audio source to the grid cap of the 6R7and chassis ground. At that point there is no volume control so keep your source level down low lest it will blast you out of the room.
Something else to have a look at is there is a muting switch that is triggered when you push in the arm that is next to the tuning knob. Double check that it's isn't muting the audio from the detector.
On the 20 ohm resistor I'd put a new one in at some point mark it down for replacement and order a new one with a high wattage rating.
Terry
You might think I'm smart but not really, I've got a 37-116 that I fixed up back in the '80's. It need a good going over again.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Terry
