Four 4-tube Radios
 

After a friend asked me to restore a 1954 GE model 419 - brown plastic with 4 tubes, I realized there were 3 more untested AA4 sets in my collection;
A Westinghouse H648T4, Stewart Warner 9180H and Admiral 4L26
https://farm4.staticflickr.com/3878/...6ac9d4f8_z.jpg

I will restore all four and compare them. I was always curious how sensitive these sets would be when the IF amplifier tube and one IF transformer were omitted. I also wonder if there were distant regions in which these would not work during daylight hours or where AA4s just were not sold at all.

Another omission is AVC, since there is no stage for IF amplification.

What is really odd is that the Stewart Warner has no loop but a long wire antenna and uses a 12BE6 instead of the 12AU6 as the other three do.

The first to be recapped is the Stewart Warner. Four paper caps, two electrolytics and three out-of-tolerance resistors were replaced. Using a signal generator per Sams schematic, I tweaked the one IF trans for 455kC, oscillator coil and both trimmers. The night reception with a 10 ft wire got only one local station, but I first tried it on a 30 foot outside wire, got pretty decent reception of the usual distant stations, for example; WBBM 780, WJR 760, WKBW 1520* and a few Canadian stations. The sound was pretty good as well.

* This radio came from Buffalo, no surprise this was the first station it picked up

I will post pictures as I work on the others.

I still hate that Autodyne convertor with a passion. Even some of the 5 tube GE's used it and some of their AM-FM sets used it also.
I remember GE quit using it in the early '60's in all but their AA4's.
50+ years ago, I had a 4 tube Arvin, using the 12SA7 and with a 100 foot long wire, it was quite a DXing machine. :thmbsp:

I have both a 3 tube & a 2-tube Arvin set, both pre-war... The 2 tube is pretty useless except for the local AM station, the 3 tuber tries hard, but its NOT gonna make me kick one of my R-3XXs to the curb.. They're metal-cased sets, small, meant to be carried by a traveler, I suppose, & were cheap enuff so he/she WOULDN'T cry if he/she forgot to bring them home...

IIRC, the three tube Arvin was a superhet, where the two tube was a TRF.
I have to consult Rider's to be sure. The sets are rather rare, at this time.
Neat sets, to be sure! :thmbsp:

Yeah, you USED to see quite a few of 'em for sale on the E place, but not any more.. I've had 'em for 10, 12 years.. The 2-tuber, it uses at least one really oddball tube. Think it cost $10 or something from Fair. Hey, they're cute as bugs' ears, they work, I luv 'em, they AIN'T goin' anywhere... (grin)

The lack of AVC should make for better diode detector performance, as there isn't any backbias from the AVC cap. Also, less tuned circuits (from a lack of a 2nd IF transformer) should make for wider bandwidth on detected audio from strong local stations. If you have a music radio station that's strong enough, and you'd want to listen to, you could modify one of these sets to become an AM tuner to feed a hifi system (of course you need a power transformer to make it safe). Most AM stations broadcast up to 10KHz of audio, but most receivers cut the top 5KHz of audio. Yes, stations are spaced by 10KHz, but not in the same city.

The Stewart Warner with the 12BE6 sounds great at work (I repaired the speaker and replaced all caps), and when I put an long wire antenna on it across my cube, I pick up the last AM station in mid-PA with music, "country gold" WI00 @ 1mhZ.
https://farm4.staticflickr.com/3881/...459cc17b_z.jpg

During the day, the SW'a reception in my shop was awful, just the two local sports-yak stations boom in loud and clear. Even my outdoor wire was not bringing much else in.
I'll try building in a loop for this little guy.
https://farm4.staticflickr.com/3907/...53e282e0_z.jpg

Tonight I'll work on the GE, which uses the 12AU6 as oscillator-converter.

To my knowledge, RCA, Motorola and Zenith never made a radio, of this type.
I'm talking about the last 65 years, nothing before that.
The JA5's didn't have much of an AVC circuit. Of course, those were the ones that were sold for under $10.00 USD. :scratch2:

The rest of the bunch on the bench
 

Before GE went to Printed Circuit boards, they had dip-solder tube sockets, making for pretty rugged sets.
https://farm4.staticflickr.com/3853/...0037c7c8_z.jpg
It has a strange IF transformer, two coils but not on the same form. The alignment went pretty fast.
https://farm4.staticflickr.com/3926/...5af1d787_z.jpg
This radio does have a fahnestock terminal on the back for an external antenna and it sure helps, especially at night!
Reception during the day is limited to only the strongest stations, while a standard AA5 will get a few more.

Next up was the Westy, somehow there is only one paper cap in this set with the remainder as disc capacitors.
https://farm4.staticflickr.com/3856/...bb82a894_z.jpg

doub;le post

The Westinghouse has a printed circuit board and not easy to solder without lifting traces, even with a 25 watt iron.
The alignment improved the reception, but it was still pretty limited unless an external antenna is connected.
The night reception was close to what the GE was but neither can match the S-W for DX, proving the 12BE6 (oscillator-converter) to be superior versus the 12AU6 (sharp cutoff pentode).


The Admiral was another story altogether. After a recap, it amplified the modulated tone at 455 kC well enough, but dead on everything else from the signal generator including the 30 foot wire antenna outside.
Maybe this oscillator is a manual-Dyne:scratch2:and needs some help.
I checked the oscillator coil and antenna for continuity, OK. All resisitors are within range.
Tuning capacitor and trimmers are not shorted, not much is left in this spartan set except two disc capacitors, which I will need to order.

Thats enough simple stuff for me, time to work on some TV sets.

I had a Zenith AA5 that was all ceramic caps. The only part to fail aside from tubes was the dual section lytic...