[electricroo]

What is the difference between socket 37-9825 and 76-1177. As the schematic states to negate with modulation hum either install a .05uf capacitor across the pilot leads at resistor 4S, or replace the socket with part 76-1177. What is the difference between the two sockets?

Ron S.

[klondike98]

Welcome to the Phorum!


I don't know what the difference is between the two lamp sockets but suspect the new one might have a capacitance incorporated into it. The capacitor would be across pilot lamp leads at resistor 48 (the 8 looks like an S on the schematic seen at https://philcoradio.com/library/download...20Book.pdf ).

I did look in the 1942 parts catalog that we have in the library but did not see those lamp sockets listed.

[DaleHCook]

I did look in the 1942 parts catalog that we have in the library but did not see those lamp sockets listed.

I have previously looked through all of the parts catalogs which we have, and I do not recall seeing lamp sockets in any of them.

[morzh]

It is probably the resistor 48; there is nno such thing as an Alphanumeric designators in the sch.

I looked at the sch of this radio (code 123) and at this point I do not understand how a 0.05uF capacitos across the pilot (it is #49) would do anything to the hum.
Introducing a ripple current that leads the current through the 53 Ohm by 90 degrees (and is lower by 3 OOM)...not sure how effective that would be.
But does not hurt to try....

[RodB]

Mike, that's exactly what the original designer said.

[morzh]

What? The ripple current out of phase?
The cap's impedance is such that it would not affect it that much.

[electricroo]

Well, it doesn't really matter but I was just curious about what the different socket was. My radio had the capacitor across the resistor. I did a total rewire including sockets and had to eliminate the field coil / choke speaker because the speaker was not on any condition to be used. I'm about to go through alignment then I will post a full video on the chassis restoration. In the meantime here's a 30 second clip of it working. Good reception in the basement even though the alignment wasn't done yet.
https://youtu.be/LyrYHvJR8AI?si=9hZFPxJfE40MgTTq