[Jayce]

I am wondering why Philco did this in their late 40's AM-FM, transformerless sets. I was looking at a 49-906 today and was surprised that they used one of these tubes and I have two junker AM-FM Philcos, one console and one table model, that use two of these tubes. Usually these were reserved for portable AC-Battery sets and other than an odd Emerson I used to own, it seems Philco was the only one to do this in their regular radios. Anyone know why? Yes, they work fine, just odd. 

[Arran]

Jayce;
  Like many things with Philco there were two things that were factored in when it came to what tubes were chosen: #1 Is cost #2 Availability. Philco was such a large manufacturer that they needed to take both into account, if they could get a deal on a rail car of one type of tube, they used them. There was one Philco tombstone, I think it was a 37/38-670 that used five 6J5G single triodes, whereas the previous 116B used one triode double diode, if you look at their roles it was obvious that they had lots of these on hand, and designed a set around using them. This was especially so in the immediate post war years (1946-48) when there were some parts shortages, Philco was continuously juggling around tube types in some models, like the 46-1201s. The only non portable I have encountered with a 117Z3 in it was a Canadian Stromberg Carlson radio-phono combo from 1950, it had six or seven tubes, other then the rectifier the rest were in series. In most series string sets, and portables after 1948, they opted for a selenium rectifier, it could deliver more current then a 'Z3 without the extra heat.
Regards
Arran

[Brad Winder]

As Arran mentioned, Philco would use a tube (or tubes) that they got a deal on, and design circuits around them. Quite often the tubes were "obsolete" compared to what other manufacturers were using at the time. But I guess you could also look at the tubes they used as being "proven" by being around for several years prior. And their sets were very good performers, so you can't say they cheaped out.

I find their early 40's sets most interesting in this regard; using a mix of Loctal, which was a brand new design, with five and six pin ST tubes, plus still using an 80 rectifier, while other manufacturers had switched to the 5Y4, etc.

[Phlogiston]

Have you seen the assortment of tubes used in the 40-190? I think it is 4, 6 ,octal and loctal. .When you can get a 42 (6F6) or a 41 (6K6) as a 6-pin or octal, they must have been using up old partsm to use the 6-pin tubes and sockets. Makes me wonder about the date codes on the OEM tubes.

[radiorich]

Hello Phlogiston ,
for sure date codes and yes good old Philco !

Sincerely Richard