The PHILCO Phorum

Two new (to me) Philco's have taken up residence here. A 38-9K console and a 37-670 tombstone.
They both will need recapping. Electrolytics have been replaced previously in the 37-670, but it must have been a while back from the look of them. This set I was told came from Alan Jesperson a few years back. It is in overall nice condition case wise and currently picks up stations on all bands.







Gene

That 38-670 is an impressive looking set, it looks like the cabinet is at least 14'' deep. What gets me is that with such a large cabinet why did they settle on using the same 8'' pincushion speaker they used in a 38-610-620? It looks like they could have accommodated one of the 10-1/2'' console speakers in that cabinet if not for the shadow meter being in the way, but adding an extra 2'' to the height would have taken care of that. It's odd that many of it's predecessors in the 16B series had a 10-1/2 incher but the 38-670Bs did not.
Regards
Arran

Its been many years since I have seen this chassis with the rectifier
tube atop the transformer. My grandmother had the console version
of this radio on her sun porch in Revere, Mass.

Good question about the small speaker. The last version of the model 116B had the small speaker, I believe that this was carried over to the '37 model year. Agree with Ron that only having one IF amplifier stage was a negative also.

BUT.... I still LOVE my 37-670B, it's a very good receiver and despite the small speaker it has acceptable sound.

ENJOY your 37-670!!

I have have also heard that these sets use a multitude of 6J5 tubes, I remember someone accusing Philco of tube stuffing the set because of that. I suppose they could have accomplished the same result with 8 or 9 tubes by designing the circuit differently, or by using twin triodes, but for some reason Philco went the other way.
Regards
Arran

As Tom pointed out, Philco switched to an 8 inch speaker in the second or late version of the 1936 model 116B, when they also redesigned the cabinet into a plainer rectangular box that is slightly shorter than its predecessor. I am sure it was done to reduce costs. The average Joe would think the 8 inch speaker sounds as good as the 10-1/2 inch speaker.

And so the 8 inch speaker was retained in the 1937 successor to the 116B, the 37-670. But I don't understand why Philco reduced the IF amplifier stages from two to one, and added all of those 6J5Gs. I think they wanted to retain a large 11 tube tabletop in the lineup, but it was no doubt cheaper to make a set with one IF amplifier stage than two.

You can see the beginning of the end of Philco's quality in the 1937 models, and the slide toward cost-cutting and cheaper products overall.

Anyway...

Gene, I see your 37-670 has a conventional 1937 power transformer. Some 37-670, 37-2670 and 38-2670 models have a larger power transformer with the rectifier tube offset (not in the center), and a 110/220 voltage switch on top of the transformer, next to the rectifier socket. My 37-670 has the odd transformer with the voltage change switch.

Yes, quite a few 6J5G tubes. This has become more of an issue with the event of the 6J5G going up in price. IF you use the cheaper 6J5GT or MG tubes you must "modify" the tube shield base. In a cinch, you can use a 6C5G tube to replace the 6J5G, but the 6C5G has a lower mmho rating.

The AF section of the 37-670 employs four 6J5G tubes (1st Audio, Phase Inverter, and PP Drivers) to drive the PP 6F6G output tubes. If you consider the mutual conductance of just the 1st Audio and PP Drivers, you have a very favorable comparison to that of the late-model 116B, which incorporates a 77 tube 1st Audio and 42 tube driver.

This makes me wonder if Philco opted for more in the AF side of the design of the 37-670 vice an additional IF circuit.

Looking at some other schematics from the 37 model year, I noted that the only sets with two IF circuits were the 37-116, 37-675, and 37-690. Philco DID add an extra AF amplifier (6J5G) to the 37-660 set, but interesting to note that the 37-665 (same # tubes as the 660) had one AF amp/driver (6K6G) and added a separate 6J5G oscillator tube and used the 6A8G for a detector only. The 37-660 combined the Oscillator/1st Detector in the 6A8G tube.

Go figure...

Oh yes, make SURE you have an extra 5X4G rectifier. Not an oft used tube in the radio world, and (for now) still very affordable.

Thanks for the heads up TA. I found a lot of 5 on the bay and have them put away for future needs

Gene