05-14-2021, 07:16 PM
Read where you can replace the volume with one 5k wire wound pot with a couple of 200 ohm 1 watt resistors to replace the dual volume original pot for smoother operation.
PHILCO 70, 7OA. ( same as 20 I assume) Replacing dual
volume control with single, tapered unit,
giving even smoother control. Circuit
is self-explanatory. The 200 ohm fixed
resistors are I watt types.
Basically you bridge the candohm with a 200 ohm resistor, tie the top side to the bottom of the pot, and at that point another 200 ohm resistor to feed the original cathode feed, the wiper of the pot to ground, and the top of the pot attaches the antenna wire feed, and also to the the antenna coil, that's it.
Found it in old Radio Service Shortcuts publication which I managed to find and download. Another member here clued me in on this, have not tried it. Also in that pub, one mentioned using an old number 1 lead pencil to smooth over the contact points on an original volume control, that was interesting as well.
PHILCO 70, 7OA. ( same as 20 I assume) Replacing dual
volume control with single, tapered unit,
giving even smoother control. Circuit
is self-explanatory. The 200 ohm fixed
resistors are I watt types.
Basically you bridge the candohm with a 200 ohm resistor, tie the top side to the bottom of the pot, and at that point another 200 ohm resistor to feed the original cathode feed, the wiper of the pot to ground, and the top of the pot attaches the antenna wire feed, and also to the the antenna coil, that's it.
Found it in old Radio Service Shortcuts publication which I managed to find and download. Another member here clued me in on this, have not tried it. Also in that pub, one mentioned using an old number 1 lead pencil to smooth over the contact points on an original volume control, that was interesting as well.
