Philco Model 20 Vacuum Tube TRF Radio Repair - 1930 - 93 Year Old Tube Radio - Part 1 [4K]

[@zorka4098]

Just catching up on this series after watching your switch repair chapter. I really like the step by step approach with the list popping up on the left side periodically. The second radio I ever repaired was a Philco 610, not as old (it was a Superhet), but you lay things out very well in how to approach these restores.

[@PracticallyFixed]

Thanks. Glad you like the list. Thanks for the comment.

[@DERB_Seymour_Indiana]

Off to a good start on this old beauty PF. Always great joy hearing the first significant noise coming out of the speaker. Dodged a bullet on that power transformer. :)

[@PracticallyFixed]

Hi Doug. Always worry a bit about transformers especially when they looked a bit tattered and opened up. Thanks.

[@mikeerstad3705]

Thanks for the video.....I have a Grebe AH-1 with the same type of circuitry "TRF"...very few componets under the chassis...most are hidden inside metal boxes but can still be checked... The Grebe works fairly well.... Mike

[@PracticallyFixed]

Hi Mike, went and checked out your video of the Grebe. What a beautiful radio.

[@user-tp1tn9yy4g]

Great video! I enjoy seeing my uncle’s project coming back to life.

[@PracticallyFixed]

LOL. Well hello there. So glad you are enjoying it. Glad your Aunt and Dad are seeing it as well. More to come.

[@y2klucker]

I have one of these. Mine is barely making any noise. But I haven't really spent a lot of time on it. Maybe just an antenna issue. Hope so. Thanks for the great video.

[@PracticallyFixed]

Cool. Check out Part 2 where we look at improving the performance as well as fixing some issues. Thanks for the comment.

[@mikeinmontana8875]

You're doing a great job on this. Philco 1930~ 👌Well done as you explain too. Especially for me! I know a little.. but not much for sure! Will check back in~ TY! Mike

[@PracticallyFixed]

Thanks for the comment Mike! Glad you are enjoying it. Thanks again.

[@mikeinmontana8875]

🤝@@PracticallyFixed

[@sgath92]

I haven't tried it yet, but I have heard that you can make nearly invisible repairs in wood/veneer cracks by using fiberglass soaked in resin like bondo'ing a rusty car by applying it to both sides of the crack and then sanding it smooth after it cures. I was eager to try it on a tombstone I accidentally impaled the top-of (something slid off a near-by shelf and went right through it) but completely forgot about the fiberglass idea and repaired it with glue, filler, sawdust and patience first.

[@PracticallyFixed]

Your video of the Majestic 307s is amazing. Thanks

[@ohioman3704]

I have a friend who is bringing me one of those to work on and was a little puzzled at first on the filter capacitor and the values as I generally only see sets using regular capacitors. What values did you use and did you use regular 630v ones. The radio he picked up is also missing the speaker as well so not completely sure what measures to take to solve that.

[@PracticallyFixed]

Hi, you have a problem there without the speaker as it is not a simple thing to replace with an aftermarket part. Not totally impossible, but very involved. Perhaps the best solution would be to find it from a parted out Model 20 set. The field coil of the speaker provides a filter choke and a voltage drop for part of the circuit. Also the output transformer after the output tubes will not likely match the impedance of a new speaker so that would need addressing. If you want to get into what all that would entail I suggest you do some research on AntiqueRadios.com forums and see what you can find. On that forum a lot of expertise is already written there. If a radio is missing an electro-dynamic speaker, I almost always pass on getting the unit unless for parts. As you know, schematics and other info are available from the excellent site NostalgiaAir.org. The site PhilcoRadio.com has additional info on the schematic which I used for the capacitance values. Since the values for the power supply filters were relatively low I did not use electrolytics but rather film types which are also non-polarized. I selected Panasonic films in 630V from Mouser just FYI. YMMV philcoradio.com/library/index.php/service-info/early-schematics/

[@brucebuckeye]

Great video! What is a B.C. resistor?

[@PracticallyFixed]

Thanks! The B.C. resistor is a multistage, wire wound resistor. It has several taps on it and is used for pulling off differing voltages for use throughout the set, including for tube bias. Thanks again and glad you like it.

[@brucebuckeye]

Gotchya. Kind of like a Candohm resistor (which was used in the decade following).

[@PracticallyFixed]

Yes, that is right. Thanks

[@sgath92]

@@brucebuckeye One of my curses seems to be whenever I work on a set w/ a multitapped wire wound resistor, at least one section of it will be wide open. I seem to find more bad ones than I do with candohms!