A few months ago I showed photos of this super hot-rodded 37-620 but didn’t have a schematic to go with it; this is the schematic and description. It began as a junker model 37-620 and slowly evolved into what can be seen on the schematic today. Since I'm not a pro at drawing and laying out schematics, you will have to accept the somewhat unusual convention.

There are no major changes in the 6K7 RF amplifier and 6A8 Oscillator/Mixer stages with the exception of a BNC oscillator output connector on the rear skirt; that signal goes to an external freq counter module which gives direct reading of the dial freq (these counter modules are available on Ebay for around $50). There is a high Q tank circuit in series with the antenna input designed to kill the local 1250 KHz station; it is not on the schematic; think of it as being an optional circuit.

Beyond the 6K7 and 6A8 circuits there is very little that remains original. The first IF 6K7 is now a much higher gain 6SG7; the 6Q7 was replaced with a high output low distortion 6J7 detector and is located in the center of the RF deck in the place formerly of an electrolytic cap; the AVC detector is now solid state; the detected audio from the 6J7 is fed to a 6K6 audio pre-amplifier; the pre-amp feeds the 6L6 output stage; and the 6L6 drives a 60 watt broadband 8 ohm PM speaker. Great attention was paid toward audio fidelity and bandwidth at all levels of output, the maximum rated output being 11 watts. Distortion is extremely low; the sound quality is extraordinary. Except for the 5Y3 and 6L6, all tubes are metal; that required tube socket changes.

The power supply uses an 8 Hy choke mounted on the speaker. Tube voltages throughout the radio have been adjusted for improved linearity; all voltages are within the proper tube parameters.

The next time I feel like taking out the RF deck, the 6K7 (and socket) will be replaced with a 6SG7. A variable bandwidth IF is under design using high Q ferrites; this circuit was installed earlier but the Q was too high and I hadn’t thought about making the Q or bandwidth variable. (The Q of a Philco IF is usually around 8-10; the ferrite Q was 280). In all of the re-design, the LED replacement for the shadow meter was left out but will be re-installed during the next round of changes.

Gas tube regulators were integrated in a previous version; they didn’t really serve any necessary function so they were removed.

There is still room for two more tubes; three if I get rid of the 5Y3. The only future limitations are from drawing too much from the power transformer; at that point the new tubes would need to be subminiatures. Maybe I'd better quit on it now- nah!

Pete AI2V

So I got it!
http://www.ebay.com/itm/1935-Philco-Radi...4ab85f719f
Cabs a little rough but nothing a gallon of glue and a couple sheets of veneer wouldn't fix!!!
Terry
What can I tell you I'm a sucker for these beater sets.

I just dragged home yet another project! I found this Zenith 10S669 on Craigslist 6 miles from my home for $30!! It's in pretty good shape overall. Someone had started to refinish the cabinet but luckily didn't mess around with the faux woodgrain areas. Bad news was that the speaker had been removed and lost, but I Bought it anyway. I got home, unloaded it and jumped on Ebay and did a search for Zenith speaker. What do you know! Listed there was the exact speaker I needed for $24.95 It is also now mine!
http://i1160.photobucket.com/albums/q500...o16005.jpg
http://i1160.photobucket.com/albums/q500...o16006.jpg

I've just purchased a Philco 60B, very nice. Pictures posted below. You can understand why I wouldn't want to strip this and do it over -- I'd like to save as much of the original as possible.

My guilt comes from the fact that I asked this question about a week ago, I think it was on this forum, and got a very long, detailed, and wonderful discourse on how I should proceed. Somehow, I didn't print that essay, and I can't find it now.

Would the person who did such a great job please have the forbearance to give me this information again? (Comments from anyone are welcome, of course.) I'd like to make this set as presentable as possible while preserving whatever I can.

Thanks very much, and my apology. It won't happen again!

David Sligar

I know RadioDaze sells these. Can somebody tell me what group of labels would be most like the Model 60 label? Thanks.

I'm restoring a Model 16 and need a good volume control / switch. This Code 125 model has a 2 meg pot with two wipers(!) Apparently one of the wipers goes to the bass compensation resistor / cap, and it appears to be inverse to the main wiper. This is probably a well discussed issue -- anyone have a good solution? Thanks!!!

David Sligar

I know that this phorum is "Electronic Restoration" so I hope my mechanical problems are welcome here.

I'm working on a 48-1263 radio/phono and have the phono working quite well with a new cartridge and all cleaned and freshly oiled. But, I have a couple of mechanical problems that still have me stumped.

The racheting teeth mechanism in the trip function seems to need a spring with incredibly small tension. Any tension at all and it stops the tone arm movement. I've seen reference to this problem, but what have others used there? If I disconnect the spring all works fine except I’ve sacrificed the trip mechanism.

I have 10 inch records to play and the tone arm was dropping in location for 12 inch records. I found that by removing the arm that controls the record drop mechanism the arm dropped in the proper 10 inch position since now the arm controlling the tone arm drop position was able to travel fully to the little adjustable brass cam that fine tunes the drop position. The arm controlling the record drop mechanism has a sliding pin that was holding back the tone arm drop arm from reaching the little brass cam. Whew, I hope that there’s some clarity in that.

I would sure appreciate any wisdom that you could send my way. I got a new cartridge from everythingradio.com, it installed great and the player is working great with fantastic sound quality, except for the two mechanical problems.

Thanks,
Alan

Hi all,

I'm restoring a Philco 48-1263 radio/phono. I had no tone variance coming from the on-off/tone potentiometer and on closer looking found one end of the pot dead ended on a terminal strip. It seems a cap and resistor were flat out missing. I replaced the cap from the pot wire at the terminal strip to the #2 pin, the plate, on the 7C6 AF Amp tube. Now I have bass, but only crammed into a very short end of the tone range. 90% of the tone range is full treble, no variance.

Did I maybe wire this wrong? I have the schematic, but I'm not terribly proficient reading them.

Thanks,
Alan

This radio has been nicely restored and plays well, but does have a few issues that I need to target. The tuning dial is a bit sloppy and the controls such as the volume are very stiff, though no crackle or audible issues at all, so tuner lube these or bad idea? Also, how do you get the lube into the volume control? Appears to be sealed.

Hi anyone help me?

I need a new dial lamp for my model 60MB
Can anyone tell me what type I need and where I can get one from?