[Amps] lk550 plate efficency

W2RU - Bud Hippisley W2RU at frontiernet.net
Fri Jan 6 07:21:14 EST 2006


Dxhogg at aol.com wrote:
> I have a lk550 that I would like to see a little more plate  efficiency on 
> 160m at the bottom of the plate choke is a 1000pf bypass if I  increase that to 
> 8000pf will I see more output on 160m without drastically  affecting the 
> higher bands
I have LK-550 S/N 001.  Given its serial number, I'd hesitate to call my 
amplifier "stock" <G>, and it may be nothing like yours, but I found it 
necessary to add some capacitance in the output pi-network on 160 to get 
the amplifier to load properly on that band with loads close to 50 
ohms.   Regardless of the other merits of increasing the plate choke 
bypass cap, I'd guess that the output pi-network components would have a 
greater effect on apparent efficiency.

BTW, with three fairly old 3-500Zs in my amp, it takes almost exactly 
100 watts of drive to get 1500 watts out on 160.  I have to go through 
the internal tuner in my Kenwood transceiver because the input SWR of 
the amp on 160 is a little higher than the Kenwood likes to see, so I'm 
probably delivering only 80 watts or so to the amp.

Bud, W2RU


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