[Amps] Alpha 76PA Plate Current

[Charles Harpole]

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 at hotmail.com   





> From: w7ry at arrl.net
> To: amps at 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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