NewYorkDave wrote:
I have obtained several of these. They were being used as line
amplifiers at my job, but are now being replaced. I've contacted the
present owner of the Dynair name in search of a schematic, but
apparently they can't help me. I thought I'd post this request on
usenet before I have to take the trouble to trace out the circuit and
draw my own schematic.

If these are what I think they are, they are modular things that can use
a similar frame for video and audio cards.

I know I have docs on the video and video sync cards, but I don't think I
have any of the audio cards.

These are transformer-coupled (UTC 0-11 input, A-22 output) and use
four Motorola 2N697 TO-5 transistors. They mount in a 2RU frame along
with a power supply (model PS-3015B or PS-3015C). I'd love to find
schematics for the power supplies, too.

The power supplies are brute-force linear supplies with series regulation.
Nothing fancy, just dual regulated supplies with a zener and a junk pass
transistor; you can find an identical design in the ARRL Handbook.

The germanium transistor amps are sort of doubtful, but whatever you do,
replace the coupling capacitors. As I recall, they do use real bias
resistors instead of relying on leakage like some more sleazy designs of
that era.

I was originally planning to harvest the transformers and throw away
the rest, but I might keep them intact since they're apparently pretty
rare (at least I've never seen one before) and just might sound cool.

Try it. Those things were very common in the video industry, and you know
how video guys feel about sound...
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."