[Amps] Alpha 87a

[Harold Mandel]

If you gentlemen recall, there was a thread some time ago on 
amplifier input cable length as regarding tuning of
input circuitry, etc.

Someone had his Alpha auto-tuning amp go into alarm
because of squirrelly RF from the transceiver.

Two remedies were proposed: That of a longer input 
coax cable and that of putting a line choke like the RF Works
types.

My smaller amplifier, a manual-tune affair, had some input
difficulty and this was because there was RF on the shield
on a short cable. By using two 6-foot lengths, one on each
side of a line choke I was able to achieve a better input match
and reduce the RF feedback that was folding back the FT-1000.

Without having the means to detect harmonic energy and display
the emissions graphically (e.g. a Spec-An), all I could do was to
work towards the cleanest setup, as the amp should just work on
whatever signal is presented, yes?

Hal
W4HBM 



[snip]
However, depending on the class of operation of the amplifier, there will a
greater or lesser degree of harmonic energy in the cathode current pulses: a
low Q network can reduce these, but the effects on measured SWR will be
there.
[snip]