Tv converters - how about this AM radio box! - Videokarma.org TV - Video

Marlin Mackley · #1 10-16-2002, 12:27 PM

Well, I figured we have over 500 posts so it was time to start a converter thread. This strange little two tube guy makes any tv into an AM radio. Just imagine having one of those 40 tube RCA projector tv's and running ALL those filaments just for AM radio!!! Well, maybe in the Winter.

Check it out:

#2 10-25-2002, 12:03 PM

I've never seen one of these! How does it work? Does it require a hard wired audio connection, say, to the TV's phono input jack, or is it an RF connection? I've seen car FM converters that output an ampllitude modulated signal to the antenna input jack of an AM car radio, but nothing that would convert an AM signal to FM!

***Eric H*** · #3 10-25-2002, 01:04 PM

Ahh, back when Electricity was too cheap to worry about

Marlin Mackley · #4 10-25-2002, 01:51 PM

wvsaz, This thing hooks up to the TV antenna, having presumably converted the freq to a low end tv channel. Talk about a waste of effort! I have not tested it.
Marlin

#5 10-25-2002, 04:50 PM

Hard to imagine how they could do it with only two tubes. It would need a frequency modulated oscillator to work with the TV, in addition to the converter, IF amp and detector for AM. Does it use compactrons?

Marlin Mackley · #6 10-26-2002, 09:51 AM

Just a 6BE6 and a 6BA6. It has a standard looking dual tuning cap, a couple of IF transformers and a tuning coil. Two grommeted holes (one empty) are for leads out, plus power. The one lead surviving is coax so maybe I was premature in assuming it was for the antenna. Might be line level audio out. I will have to open it up when I have time to see what is going on and what wiring would have come out of the other hole. Too busy right now catching up with work - been sick.
Marlin

#7 10-26-2002, 10:08 AM

I think you are correct about the line level output. Sounds like just a simple AM tuner, with the 6BE6 for the oscillator/mixer and 6BA6 IF amp. I'll bet it has a germanium diode detector. Will be interesting to see if it has a power supply, or is designed to steal B+ and 6.3V from the connected device. Should be rare and worth holding on to.

jshorva65 · #8 10-26-2002, 12:30 PM

My guess is that it likely contains one of those tiny Stancor (or equiv) power transformers. Barely the size of a 2W SE audio output unit, they provided 125-0-125VAC @ 10mA and 6.3VAC @ 600mA from a 115VAC primary. A single selenium rectifier and filter cap under the chassis would provide half-wave rectified +300V or about 160VDC with a pair of rectifiers in a full-wave circuit.

#9 10-26-2002, 07:17 PM

160 VDC is all it would need; that is typically what is used in the "All American Five' circuit using 12BE6 & 12BA6.