James Nelson wrote:
> Transmitters and such do not like elevated temps.
> around them. So I put a fan to blow on the hot ends of the units and put
> a 2" x 4" vent on the top of the panel over the radio stack to let out
> the hot air.
Please excuse some technical commentary here re transmitters, but
elevated temps are moot re the final transmit stages. I fear the
impression we may need to cool a comm box to make it work right.
Whether or not the A200 in the overall can take elevated ambient temps
is one thing, but in xmit function alone forget about it. I've seen it
numerous times on the test bench on various comms.
Aircraft comms are designed for very brief transmissions and low duty
cycle, but in tweaking them for much longer periods, all that happens is
the temps around the final, heat-sinked transistor output stage rises,
like a lot, but not one whit decrease in power output, or even distorted
detected-audio output on the "scope" for that matter. There's a
technical explanation for all this, but to put out 7-8 watts into 50
ohms swinging a fraction 14V (or even less) supply voltage, well there's
ways to do that and get away with it, but ambient temp sensitivity ain't
one of the issues.
Regards,
Fred F.
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