The PHILCO Phorum
41-300 Phase 2 restoration - Printable Version

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RE: 41-300 Phase 2 restoration - RedRobot - 03-09-2026

Over the weekend I installed the fuse and aux in. Success! The phantom voltage is gone too even for whatever reason. Not like the fuse changes the arrangement of the safety caps or anything. And the aux in audio is much cleaner than AM transmitter.

Remaining oddities: It has a bit of hum even with volume down that it didn't before. Nothing awful but noticable. Also despite doing a DPDT switch to send the radio in to ground, switching it to aux only attenuates a strong station, not silences it. Neither are crippling so I can troubleshoot them later.

I ordered some mica caps and an inductor to jury-rig an antenna coupler, though to make it more permanent I'll have to figure out the right size pins to plug into the connector. Those should arrive this week. After that, next phase will be working on the peeling veneer on the center column of the cabinet. I got some Titebond, syringes, and an iron, but details fit better in the other subforum. 

I also am thinking I need to align the radio eventually since the dial seems off and I get dual peaks on some things, so I was looking into the details. Seems straightforward when you have the equipment, I just don't presently, so it's not an immediate thing so much as once I have the right test equipment.

1. As I understand, signal generator+oscilloscope is the best way to align but signal generator + voltimeter will work? I could look for a cheap oscilloscope, there are other things I could use it for in the vintage PC sphere, but it hasn't been a priority.
2. Would one of those cheap TinySA spectrum analyzers work as a signal generator for IF alignment? It looks like some people have done it, but has anyone here tried that?

Thanks again, everyone that's given advice on this. It's been a ride the last couple of months, and I think I started on hard mode in terms of vintage radio models to work on, but I'm really feeling the results.
2. What

RE: 41-300 Phase 2 restoration - RodB - 03-09-2026

I have been using an rf signal generator and a VTVM for over 10 years. Connect a coil of wire to the generator output, sometimes to a tube signal grid through a 0.05 mfd cap. Monitor the AVC with the VTVM because it's more sensitive to signal variations. You can use a DMM instead but it's harder to see variations. Using a scope and sweep generator is for Hams who need to have precise settings. For our purposes, it's a little overkill. Go ahead and use them to get a better feel for how things function.

RE: 41-300 Phase 2 restoration - morzh - 03-09-2026

I agree, a scope, while nice, is not a necessity, especially when aligning and not troubleshooting.

RE: 41-300 Phase 2 restoration - MrFixr55 - 03-09-2026

Re the hum, check the "lead dress". If the audio wires to the switch are long, use shielded cable. Ground one end of the cable to the chassis. Also, verify the correct wiring of the filter caps.

Re the Phantom voltages, what the others said is correct. The original Philco arrangement was to have the 2 power line bypass caps in series with the center junction connected to chassis. (If you have the chassis grounded to a water pipe (or even to the house wiring), the phantom voltage will be gone. An alternative to the original wiring for these RF Bypass caps is to place one cap across the power line (post power switch) the other cap from the leg without the switch to chassis ground, and to install a polarized plug so that the switch side is Hot and the unswitched side (with the cap to chassis is Neutral. This would eliminate the 60V (low current) on the chassis. However, the noise may either decrease or increase.

RE: 41-300 Phase 2 restoration - RedRobot - 03-12-2026

I think I might get one of those combo multimeter/basic oscilloscopes eventually either way, but good to know it's not a must. So I'll look for a cheap signal generator perhaps once I feel up to doing alignment.

The wires are a bit long since they cross most of the width of the chassis given the switch is in back and the #46 cap is near the front. Shielding couldn't hurt. Should the ground from the audio jack (or where the radio in gets switched to ground) go through a resistor, or straight to chassis? It seems like every discussion I find about adding in an aux jack suggests different resistor values for left and right for the stereo-to-mono conversion, while some suggest resistors on the ground and some do not.

Parts for the antenna coupler arrived too but I have the chassis out so I can glue some veneer and I took the long wire down since ants were coming in along it when the weather turned nice. I'll get to it eventually.

RE: 41-300 Phase 2 restoration - radiorich - 03-12-2026

Hello Red,
Far as combo multimeter/basic oscilloscopes I also thought about getting one.

Veneer work is one task I am not that good at I have few sets that need it to.

Sincerely Richard

RE: 41-300 Phase 2 restoration - morzh - 03-12-2026

Shielding only works when it is connected directly to chassis.
The idea is for it to be at the common/GND potential and to be the drain for the stray/return currents.
Otherwise it will hurt more than it will help.

RE: 41-300 Phase 2 restoration - RedRobot - 03-15-2026

Glued down the peeled veneer,  not super aligned but it's hide glue so i can revisit later maybe.. Old English was magic on the scuffs.  Reassembled and about ready to place in the downstairs hall until I'm ready to tackle alignment . 

   

I still need to test the antenna,  but after that I'm going to work on setting up a more 90s stereo for upstairs.

RE: 41-300 Phase 2 restoration - MrFixr55 - 03-16-2026

Nice job, Red! A rather handsome set!

RE: 41-300 Phase 2 restoration - radiorich - 03-16-2026

Hello Red,
Wow, you’ve really outdone yourself on this one. Nice job!

Sincerely Richard

RE: 41-300 Phase 2 restoration - Paul Philco322 - 03-16-2026

Very fine job, nice. Paul

RE: 41-300 Phase 2 restoration - morzh - 03-16-2026

Very good looking radio.
Matches the piano too!