Holy Grail of Philco

[Retro Ron]

Hi, I'm new to this forum but not to old radios. I'm no expert on Philco but I have a 71 and a couple 89s I restored myself and they are good radios. I was just wondering of all the different Philco radio models, what would be the most desirable model and why?

Regards,
Ron

[Ron Ramirez]

Hi and welcome.

You have three very good Philco models. While the 89 is sometimes cursed for its oscillator coil problems, it can be an excellent receiver, as you have found.

Most desirable Philco model and why? I would say the 38-690. Tubes, tubes, tubes. 20 of them. Plus a 14 inch woofer, two 6 inch tweeters and four 8 inch passive radiators. High fidelity supreme. It was the pinnacle of Philco engineering; they never made another like it.

That's one man's opinion; that's all. Let's hear yours...

[Fred R]

Hi , I have to add to what Ron has said. The 38-690 is at the top but I think the previous year's 37-690 is right there with it. I have both and can compare them. I also have a 680 with the dial under the lid. I prefer the 37-690 myself. Others don't like the cabinet with doors. I like the triode output (6B4Gs) of the 37-690. The only thing I don't like in the 38-690 is the bass compensation circuit. On the 37-690, they use a 6K7G as the bass amplifier. It is used because the remote cut-off grid is operated off of a DC voltage derived from the 6F6G driver tube. The lower the volume setting, the more the bass gain is increased. Philco used a similar circuit in the 680 using the pentode of a 6F7 but it works the same. The 38-690 varies the bias on the supressor grid (grid 3) of the 6K7 bass amplifier. I don't find it works as well as the two previous models. Curiously, Philco disables the bass amplifier when the band switch is on any shortwave band on all three models.

Sensativity wise, both the 37 and 38 690s perform about equal. Ron's notes on correcting the out of phase tweeters in the 38-690 restored the high end on mine. Even without tweeters, the 680 is no slouch either.

Fred

[Retro Ron]

Now that I know what to look for, I'll have to keep my eyes open. I don't suppose they made a tabletop version? A quick look at the schematic reveals what a beast the 38-690 really is. I thought my 89 was difficult when the osc wouldn't run. I had to rewind the coil and play with the cathode resistor but now it's a solid performer and a daily driver. Perhaps there's something to be said for simplicity.

Thanks,
Ron

[FStephenMasek]

Fred, thank you for your discussion of the bass compensation circuits. It is interesting to learn more about the various approaches used in different radios. I'm fortunate to own a Scott Philharmonic (30 tubes), so have the opportunity to try to understand the approaches used in the many circuits in it as I restore it (it was damaged by the seller).

[radiorich]

Hello FredR,
well that 's some great info you posted .
Sincerely Rich
P.S. I don't have either of those sets but when it comes time I'll know what one not to buy.
the bigest set I have is a Ge s-132 lowby that someone hacked the legs off of I'm going to have buddy turn new ones but far as Philco it's my 20 deluxe but it needs the fret work fixed on the grille thou.
I'm not looking foward doing that I don't mind electricaly restoring it but the finishing work dealing with toners and dyes is what gets me.

[Fred R]

Hi Rich,

If you ever get the chance to buy either, grab 'em. I told the story a long time ago on this forum. A friend I don't get to see much anymore had a few nice radios. He introduced his fiance to me and her first comment was "I hate radios". It didn't take long but he sold me the 38-690 and a Zenith 12-S-370. I sold the Zenith because another friend of mine liked it better than I did but I kept the Philco. You never know where something like this might turn up.

The 680 is a great performer also but is a pain to get the chassis out of the cabinet. The chassis hangs for the top and unless you have strong arms that can hold the chassis while removing the screws or have someone holding the chassis while you remove it, it is difficult. I ended up laying the 680 face down. With my shoes off, I climbed in and was able to remove or remount the chassis in place. Later 680s have the chassis facing forward and are easier to work on.

Fred

[radiorich]

Hello Fred,
nothing like getting to your work
thats sounds like some crazy things I did when replacing picture tubes in console tvs like the 80s Sony 27 in and 30 in tubes they were beasts.
Sincerely Rich
P.S. thanks for the tip