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Interesting problem with Philco 38-62 - Printable Version

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Interesting problem with Philco 38-62 - TheUniversalDave1 - 02-18-2016

Ever since I've owned this radio, (almost a year), it has had come-and-go problems with the RF amp circuit. It needs a really strong antenna to work passably well. What normally works on all my other radios, you have to multiply it by five for it to work on this radio. It stopped working last night, and I immediately turned my attention to the 6A8G. I put my finger on top of the grid cap and the wire that goes to the tuning condensor and it immediately starts blaring my 1410 KHz AM transmitter tunes. I pulled the schematic, and I'm going to see if changing the tube and replacing the wax capacitors in the RF amp circuit help.

Side note, this radio has the broadcast band and 2.3 to 2.5 MC band. I'd like to make use of the band switch, since 2.3 to 2.5 is dead now. I want to turn it into a tone switch, but I bet it isn't as simple as unsoldering the wires and sticking in a capacitor that goes to the audio output across the switch.  

RE: Interesting problem with Philco 38-62 - morzh - 02-18-2016

Have you check the antenna transformer integrity yet? #2?

RE: Interesting problem with Philco 38-62 - John Bartley - 02-18-2016

Yup, I agree. If substituting your body for the antenna coil results in a good signal being produced from the 6A8G, then I would suggest that there is insufficient signal getting thru' the antenna transformer into the 6A8G

RE: Interesting problem with Philco 38-62 - TheUniversalDave1 - 02-19-2016

Oh boy. That looks like a joy to troubleshoot.

RE: Interesting problem with Philco 38-62 - morzh - 02-19-2016

This is not bad at all.

In the coil #2 measure between pins 1-2 (25 Ohm) and 3-4-5 (2.5 ohm from the center to either end). If it checks out and the soldering / wiring is good, then we move elsewhere.

RE: Interesting problem with Philco 38-62 - TheUniversalDave1 - 02-19-2016

Okay, I can probably handle that. But not until March 12th when I get to go back to the Radio Club.

RE: Interesting problem with Philco 38-62 - morzh - 02-19-2016

You don't have a meter at home?

RE: Interesting problem with Philco 38-62 - TheUniversalDave1 - 02-19-2016

I have a Voltohmyst, but it has issues.

RE: Interesting problem with Philco 38-62 - morzh - 02-19-2016

As long as it can reliably show short from open, it is enough.