My friend and I fixed my 76PAC (the P must mean 3 tubes, and the C indicates
a hypersil xfmer) on the meter circuit but we can't remember what
we did... Nevertheless, into a dummy load, at 1500 out,
the plate meter pins. The grid current is kept
safely below 1/3 scale on the other meter.
Personally, I like the meter pinning because
it gives me another db or so into the contact's
receiver..... just like the added db u get by putting
up an antenna while it is snowing.
It is not a bug, it is a feature! 73,
Charles Harpole
k4vud@hotmail.com
> From: w7ry@arrl.net
> To: amps@contesting.com
> Date: Thu, 30 Jul 2009 20:03:02 -0700
> Subject: [Amps] Alpha 76PA Plate Current
>
> I have acquired an Alpha 76PA with 3 8874 tubes. I get 1500 watts output with
> 75 watts drive but the plate idling current in the SSB position is almost
> 400 mA. At 1500 watts out, the meter is against the pin! Grid current is
> around 75 mA.
>
>
> Doing some searching on Google, I see the solution to the plate current meter
> indicating high plate current is to put a plate current doubler on the meter.
>
> Why not just fix the circuit? Why does the meter read so high? Bad design?
> Bad component? I really dislike fixing the symptom.. I would rather fix the
> problem.
>
> I have run a spot check on the metering resistors and they seem to measure
> ok. Has anyone actually fixed the plate current metering circuit?
>
>
> Thanks
> 73
> Jim W7RY
>
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