[Moon-net] W6PO amp input mismatch issue resolved !

[David Smith]

Hi Hugh,

Sorry to hear of your challenges with the W6PO input circuit, and a pity 
I didn't notice your original posting at the time.

I also use an FT847 to drive a K1AGB-design 8877 amp on 2m.  The K1AGB 
design uses striplines for the anode side, but borrows the W6PO input 
circuit.  I also could not find the variable inductor, nor any details, 
so I just wound a coil of "N" turns  and prepared to experiment.

http://home.exetel.com.au/dwsmith/amps/8877_2m_Input.jpg

However, I must have struck it lucky.  My PA tuned up first time, and 
provides a near perfect match for the 847 - no need for an external 
tuner or anything.

A bit late now, but for future reference, my guesstimate from the photo 
is that it's 6 turns, #14 5/8" long, 3/8" ID.

BTW, with 4kV on the anode, the 8877 really steams.  Pity we can only 
run 400W in this country :-(  Still, I'll be ready if ever I move to the 
country and get one of the rare "high-power" permits.

Regards,
Dave
VK3HZ