Friends,
The three responses received within a few hours after my posting are
greatly appreciated. I have decided to scrap the idea of "no input tuning" and
immediately pursue using a switched-in tapped, tuned circuit for each band. I
figure on initially setting the tap at the 60 percent point from the bottom end
of each coil (in the parallel LC circuit). I will adjust Q by adjusting the
LC ratio so that it will work OK over each band. I was especially interested
in the amps reflector response number 9 which even included a suitable
rule-of-thumb input resistor of 90 ohms for realistic 4-1000 tests without
applying any of the tube's voltages. I'm sorry that I do not have time to
supply any further information to you guys, as I've already put my name in with
about 90 others who expect to be working the SSCW contest this weekend.
I can say that I originally built this amplifier in the days when all
transceivers were of the tube type. That is, all had output tuning and loading
controls that allowed amplifier's SWR of 2 to 4 to be matched OK. There was no
consideration ever given to impedance matching within the amplifier.
While I will eventually install tuned circuits for all six HF bands, I may
omit 160m and 10m for this weekend's activity. Go PVRC!
Thanks my buddies,
John, W8OHT
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