[TenTec] Orion 1 & 2 "Talk Power" problem (Ron Castro)

[M. K. Hess]

Being one of the folks who contacted Ron about this issue, I took the
opportunity last week to
analyze the schems for the O-II. Without getting into lots of detail, the
ALC function is BOTH
analog and digital. If you look at the ALC (section 5) schems. you see the
fwd power coming in
from a diode on the IF board, being compared to a voltage through pot R179
and the "Analog ALC"
control signal heading off to the ADC, to the processor and DSP, and then a
DAC converts the
processed signal back to a control voltage going to the IF board (I'm
quoting from memory w/out
digging out the schems. again). So the BL is that while the actual ALC
control signal is derived
by a fairly typical ALC Op-Amp circuit, and the ALC activity threshold can
be internally adjusted
by varying the RC, the DSP is adding further "coloration" to the signal.
That's what brought me to
the comment I made earlier in the week, suggesting a nice O-II enhancement
may be a menu item that
allowed the operator to modify the parameters of the digital part of the ALC
"coloration".

Regards, Mike Hess, N3EAQ