>All prior wattages
> measured with bird wattmeter. Higher drive power just gives higher grid
> current with no additional power out. Grid current looks "normal" and
> driving power is about 35 watts, plate current is about 700 ma at 500
watts,
> 350 at 250 watts with plate voltage on ssb position or about 1.6 to 1.8KV.
>
> Another curious observation was the forward and reflected meter readings
> were identical - it looked like all the forward power was identical to the
> reflected meter amounts, but the amplifier was feeding a heath cantenna
and
> the bird wattmeter indicated no reflected power and all forward power as
> noted above. Wonder if some vhf or other currents are circulating in tank
> circuit and messing up the metering and/or causing the low output on
higher
> frequencies.
It might not be that complicated. I'd check the path between the point where
the internal meter samples the output and the UHF output connector on the
back panel. A loose connection, bad coax or bad connector would show a high
fwd/ref ratio to the internal wattmeter that would not be seen by the
external Bird. I don't know the 76A, but if the output relay is after the
internal wattmeter directional coupler, the relay contacts may be dirty or
pitted. Alpha's web site says the 76A uses an open-frame relay, so it should
be easy to check.
73, Dick, WC1M
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