What a delightful little find at St. Vincent DePaul thrift store!
I wasn't at the St. Vincent store to BUY anything.... I was there dropping junk off.
But out of the corner of my eye, while the XYL was telling the loaders what to take out
of the SUV, I spotted this little box - 4" x 4" in the front by about 6" long... looked
like a vernier dial on the front - sitting on a pile of junk metal that would soon be picked
up for recycle. So I grabbed it and asked the yard guy for a "buy ticket" (Our St. Vincent
DePaul store has an outside yard - the yard guys price things on the spot and you go inside
and pay - otherwise, most yard stuff goes to recycling or the dump). He hemmed and hawed
for whatever reason and finally said "four bucks"... fine. Sold.
I assumed it was an audio generator or maybe a VFO - only has an RCA jack on the back,
and a power connector - labeled 12v AC or DC for filaments, 200v for B+ - AHA!! It must
have a tube in it! Nice National vernier dial on the front, with 2 POTs, a toggle switch (on/off?),
and a green power bezel. Yep - gotta be 1 or 2 tube signal generator or some such.
My plan had been to be use the vernier for a VFO or regen project... not much more than that.
Tonight I finally got around to opening it up... HOLY CRAP!! It's BEAUTIFUL! SIX TUBES!!!
In a box 4" x 4" by 6"!!! It's so well built that there are no screws to hold the chassis in the
case - it slides in - PRECISELY - not the other way 'round, but the way it was meant... and fits
like a glove. Amazing construction.
Underneath the chassis is as tight construction as you'd see in any professional radio of the
50's/early 60's - amazingly well engineered, considering this is a "one off" made by an Amateur.
So what is it? A VHF receiver covering 105 to 135 MHz - aircraft band. And it's a superhet - with
TWO IF stages... antenna in on the RCA jack on the back, audio out via the 1/8" headphone jack
on the front, top left.
I'm in the middle of a major shop overhaul, but as soon as the bench is cleared off and I work through
some other "fixit priorities" I'll power this little beauty up and see what she does.
Needless to say, I WON'T be converting it to a VFO - it'll just sit in my shack - and if it in fact works,
and is stable, will monitor AM aircraft signals from the Tacoma Narrows and Seatac Airports near me.
Great find, saving it from the skip is also pretty neat. I once found an old farm model ambc set at the goodwill for like $1.88 or so. Powered it up and worked just fine. Never know what you might find in those places.
now with true viterbi decoder!
To me, it looks like an older, tunable, receiver that was mounted in an aircraft which has had the dial replaced, maybe the front panel as well.
No I don't think so... up close you can see the hand cutting evidence in ALL the holes - like the "H-slots" below
Originally Posted by K9STH
the IF transformers - irregular cuts - nicely done but all different - not stamped out. There's a few "mis drills"
for some screw that ended up in the wrong place by mistake - non "mil-spec" parts - LOTS of evidence of
cutting and filing in the aluminum. No, this in my mind is 100% quality homebrew. And of course, the
the 3 IF-style transformers are all "consumer grade" and retail labeled units from Miller Co.
Honestly, I really truly wish it was just a crappy little signal generator or something - I REALLY wanted to
gut it and build a 40-meter VFO for a transmitter I'm building. But the build quality of this little box is
so good (at at the same time, so clearly homebuilt to anyone who knows true homebrew gear) that it
would just kill me to undo it.
So when I get done with my current shack/shop overhaul, it'll just be on display without the outer case just
as an amazing little object for ham friends to pick up and ponder.
Of course, not before I put 200v on the B+ and 12v on the filaments, attach an antenna and earphone,
and TRY IT OUT FIRST!!!! It'll be a while but I'll revive this thread once I've tested it. I have several
airports nearby with lots of air traffic - if the dial markings are correct, and it still works, I should hear signals.
That is really nice looking.
Someone had a ball building that receiver.
You cannot rule an educated population.
I agree, that is a very well done homebrew receiver. Most noice!
You say it looks to be a hand built one off, I would provide the speculation that it is a prototype light aircraft receiver. That would account for the holes and non-spec parts.
I have a single remaining example of an aircraft transmitter ( Aircom TVT-1) from the mid-60's that my father(W5OXL SK) and some other aviation enthusiats developed and got FAA/FCC acceptance done on it. I remember the prototype being fairly crude being built on perf-board.
Another idea is that it is a copy of a commercially available light aircraft receiver from the 1950's or 1960's.