[37silverstreak]

I just brought home this Fairbanks Morse 9A I found locally on Craigslist for 40 bucks. The seller is the daughter of the original owner. At 76 years, she and the radio are the same age. A very nice lady, she remembers listening to it as a child. She is in the process of moving into an apartment complex and is selling off stuff. she was very glad to see it go to someone who would appreciate it and I for one was very happy to get it!!!!!!! Here are some pics. It is a very neat set and in relatively good condition.
Kevin
[Image: http://i1160.photobucket.com/albums/q500...323d60.jpg]
[Image: http://i1160.photobucket.com/albums/q500...50e8e7.jpg]
[Image: http://i1160.photobucket.com/albums/q500...ad8dec.jpg]
[Image: http://i1160.photobucket.com/albums/q500...c3572a.jpg]

[Electrothaumaturgist]

Pretty nifty looking radio!!! That grill cloth looks to be in good shape also! Nice find! congrats! Love the face, too!

[Skip]

Kevin pm.

[morzh]

She's a magnificent beast!
If you can make the cabinet come back to the former glory, it will be the centerpiece.
My white envies!

[y2kbruce]

Nice find. You are fortunate to still have the turret shield with it. You did not show the speaker but if its like the one I had the speaker is mounted to a 22" wide copper or metal enhancer. Makes the speaker look huge.

[Jayce]

Very nice looking. I tried to find a Fairbanks-Morse radio for a while since I own a few of the old Fairbanks-Morse single cylinder engines and had one of thier scales years ago. Never have seen any in my area.

[Arran]

It's sort of strange that they would build a big nine tube console like that with only a single ended power output stage. There were some Motorolla models that were the same way, and even a Canadian 10 tube RCA set with a single 6L6 for an output that I spotted on craigslist once, not in my immediate area though. I'm not sure why they would do this but they did.
Regards
Arran

[jontz]

OK, super noob question here, but how would most higher tube count radio output sections be set up? As a class A push pull?

[morzh]

Probably as AB pushpull (at least transistor ones are always AB). That means that mostly it is B (conducts for half-periode) but also conducts just a tad beyond that so both halves conduct at the same time when the tubes are almost open. That eliminates that infamous "step" that occurs when both halves do not conduct in B pushpull.

But say my 9-tube Zenith 9S262 has Class A Single-ended amp for the output.

Sounds good enough. The disadvantage of A vs AB is that one tube conducts all the time, hence lives shorter life. Also SE transformer is larger than Pushpull, due to the permanent magnetizing creating saturation, and so it is more expensive, often twice as.

[Arran]

Most tube radios with push pull outputs used class A, though some used class AB, and some used class B (class B in battery radios mostly). None of it is really relevant to restoring a radio, it has more to do with how the tubes are biased and with power consumption. Some would use an audio interstage transformer to drive the output tubes but many later 30s sets used a phase inverter.
Regards
Arran

[Jayce]

I could never figure out why some higher tube count radios have only one output myself. I've fun across numerous RCA and GE consoles like that. 9 to 11 tubes and only a single 6V6 or single 6L6 for an output. Sometimes they have two 6V6 tubes, but only one is the actual output! That's why I was surprised when that GE console I got in the deal with Apple IIe computers actually has push pull 6V6's. On the other end of the spectrum, my Coranado chairside only has six tubes, but still has push pull 6K6's.

[Arran]

If a six tube set has a pair of 6K6s, if it does not have an interstage transformer they may be connected in parallel, or they pulled that screen grid inversion trick like Philco did.
Regards
Arran

[TA Forbes]

WOW!! And it HAS the "turret" over the chassis!! Often this feature was discarded in the past, usually by a "technician" unwilling to re-install it after repairs.

Nice shape too!!

Several manufacturers resorted to a single-tube class A output. For many folks five to seven watts output was plenty for their living room.

In fact, I suspect that the number of watts output a set could develop was considered in the same manner that the number of ponies under a sport car's hood was by a potential buyer. In both cases the full potential of the radio or the car would be rarely if EVER be used.