I would invite you to join the Yahoo rfamplifiers group and ask the
question over there.

http://groups.yahoo.com/group/rfamplifiers

cheers,
s.

: Richard wrote:
: I need some information on an appropriate input circuit for a small RF power
: amplifier using a 2E26 operating in the HF region. Output would be about 27
: watts. Drive input power about 0.12 watts.

: I want the input circuit of the PA to present a 50 or 75 Ohm load to the
: driver (the exciter - probably a CW QRP rig - will supply about 0.12
: watts). Perhaps (I muse) it would be good, (certainly it would be
: convenient) if the input circuit was NOT a tuned input circuit, but see
: below.

: Questions (that incidentally show my thinking):

: Can anyone point me to a website that gives the design data for an
: appropriate circuit given the things I have mentioned?

: Is it okay to have an untuned grid circuit? I muse no problem if the
: exciter has a pi-network output circuit. I just wonder that if the exciter
: uses a pi network, if that would represent both the exciter anode/collector
: tank circuit, and the grid tank circuit. (So, really there would be a tuned
: input circuit - the output pi-network of the exciter). (Just shows I know
: nothin', I'm not even certain whether solid stage rigs use Pi-networks to
: match with the load).

: Any thoughts on biasing arrangement - fixed bias, drive bias, or cathode
: bias? (Perhaps fixed bias is best - no need for a clamp valve). Grid bias
: needs to be about - 45 volts. Muse that a simple RF choke supplying the bias
: to grid would suffice.

: So, basically, I want to be able to plug a QRP rig into the PA, tune up the
: QRP rig and the plate circuit of PA, and that's it.