[TenTec] Omni VI and non TT Amp

[Paul Christensen]

> "Cuz an Omni VI doesn't have ALC jack.  Where you going to pug it in?
73 de K1ESE
John"

There's nothing wrong with the concept of ALC between the transceiver and an
amp, but more often than not, the real-world implementation is nothing more
than a "feel good" exercise that leaves the operator with a false sense of
security.

>From what I've seen, the better ALC systems are employed within a product
line under one manufacturer where the designer can calculate the ALC voltage
"meet me" point with some semblance of precision.  For this reason, ALC
within the transmitter section of the transceiver is much easier to manage.
Even when some form of ALC voltage adjustment is used between an amp and
transceiver of different manufacturers, the ALC transient dynamics may not
be optimized.  Simply connecting an ALC cable between a transceiver and amp
is no guarantee of good linearity and amp protection.

For this reason, I have always shunned the use of ALC and try to pay
attention to proper amp drive level and loading to ensure maximum linearity.
A better means of proper amp operations includes the use of a scope in
trapezoid X-Y mode between the input and output of the amp.  

Until the advent of DSP, an even better method consisted of applying mic
audio to one set of scope plates while applying final RF to the opposite
set.  The benefit is that the entire system from mic to amp antenna port is
used to measure total system linearity.  However, since transmit DSP
introduces latency, even if slight, I've found that method no longer gives
an accurate display of linearity.

Paul, W9AC