----- Original Message -----
From: "R.Measures" <r@somis.org>
> Some mornings, 20db more Tx suds produced 20db more Rx signal and on
> other mornings, 20db more Tx would make c. 23db more Rx signal. There
> appeared to be no way of controlling anything. It was: what you see is
> what you got, and you can't change it a jot.
>
So what you are saying is that at one instant with the
8171 off the signal was S-xx and then in the next instant
(e.g. in the span of a few seconds) the operator turned
on the 8171, and the Rx signal went up by 23dB even
though the increase in tx power in that same instant
was only 20dB? That would imply that the ionospheric
plasma heating due to the 8171 output was almost
instantaneous. If that were true, I would expect that the
thermal conditioning of the plasma could follow the
syllabic envelope thereby causing distortion. And
if 16KW PEP to a dipole would cause 3dB distortion,
the just imagine how bad a foreign broadcast station
would sound running AM with 500 KW to a curtain
array. If the thermal conditioning were a bit too slow to
follow the syllabic envelope, then you would be able to
see some droop on the RX audio output (w/agc off) if you
pulse modulated the 8171 exciter between say 1 watts
and 100 watts with a 50% duty cycle square wave.
Anyway, I don't have a stiff enough service drop to
run an 8171, so I guess I don't need to worry about all
this :)
73 de Mike, W4EF...........................
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