On 2019-03-09 12:59 PM, KENT TRIMBLE wrote:
Some brands require a one-time ALC calibration procedure prior to
use. Once properly configured, they are usually free of the
distortion Don rightfully talks about.
Regardless of "calibration" most non-Elecraft transceivers have
significant ALC related distortion whether one is using an amp
or not. Quite simply, most non-Elecraft transceivers develop
their ALC based on *excess drive* to the final amplifier (a carry-
over from tube based amplifiers where ALC was developed when the
tubes started to draw grid current as they moved from class AB1
to AB2) and run excess drive in order to do so.
The excess drive plus overdrive sensing creates a situation in which
some combination of IF amp, driver and final amplifier are operating
in the compression region *AND* the ALC time constant allows an initial
"overshoot" (or power "spike").
73,
... Joe, W4TV
On 2019-03-09 12:59 PM, KENT TRIMBLE wrote:
Along with this, it should be noted (especially for new Amateurs) that .
. .
Don is correct (always is) concerning the non-employment of ALC with
respect to Elecraft transceivers which produce power differently from
other brands. On this reflector, the recommendation not to use ALC
pertains solely to Elecraft products.
However, many Elecraft owners own and operate other brands of
transceivers and amplifiers. When using those other brands, the
instructions provided in the transceiver manual AND the instructions
provided in the amplifier manual about using ALC should be followed,
especially with solid state amplifiers. Those instructions often differ
from those recommended by Elecraft. Some brands require a one-time ALC
calibration procedure prior to use. Once properly configured, they are
usually free of the distortion Don rightfully talks about.
As a friend of mine puts it, the ALC controversy borders on being a
religious issue.
73,
Kent K9ZTV
On 3/9/2019 11:01 AM, Don Wilhelm wrote:
Bob,
It is important to understand that ALC does not control the amplifier,
it is an attempt by the amplifier to control the transceiver.
ALC is sent FROM the amplifier in an attempt to control the power of
the transceiver.
Used indiscriminately, that will cause distortion in the driving
transciver.
Elecraft does not recommend the use of ALC for power control because
of that. Set the power output of the transceiver to drive the
amplifier properly and adjust the amplifier ALC to produce no ALC at
that point. If the amplifier has fault detection, then ALC can be used
to drop input power if a fault occurs - that is the only legitimate
use of ALC.
So in many cases, an ALC connection is not needed.
73,
Don W3FPR
On 3/8/2019 9:11 PM, Bob KD7YZ wrote:
Wondering how to do this.
I see a cable on https://www.arraysolutions.com/k3alc
A K3 ALC cable ...
or any other ideas ?
I have a W6PQL 2m SSPA with an ALC input on the back
many thanks.
--
73
Bob KD7YZ
AMSAT LM #901
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