FYI, the new Flex 6000 series radios have standard hardware ALC. I
don't know for sure, but I THINK Flex was the only major manufacturer
not providing it in their radios until now.
Jerry W4UK
At 09:32 PM 8/27/2012, Jim Barber wrote:
Then I stand corrected. Some of the newer solid-state amplifiers
will indeed work in
the manner you describe.
If there's a choice, I still believe ALC is a bad means by which to
achieve a good thing.
If you happen to have their wattmeter, then this might work without
the radio connection:
http://www.arraysolutions.com/Products/alc_alarm.htm
I don't want this is to turn into yet another thread about the
pluses and minuses of ALC.
I agree that some kind of fault signal should exist between a modern
amplifier (or wattmeter)
and the exciter to shut down drive gracefully on a load fault
condition. I won't concede that
ALC is a *good* means by which to do that, although it may be the
only means in most
circumstances.
How about a compromise? Instead of herding cats by proposing a standard for
amateur amplifier/transceiver ALC operation, why not just finish the
subversion already
started and make the ALC line operate as a comparator at the
transceiver? In other words,
if the negative-going ALC ramp goes past [some negative number] then
the rig interprets that
as a VSWR fault, and gracefully shuts down the drive and rings bells?
Thanks,
Jim N7CXI
On 8/27/2012 4:51 PM, Jerry Flanders wrote:
At 04:38 PM 8/27/2012, N7CXI wrote:
IF amplifiers fed back some kind of ALC ramp to the exciter on
VSWR fault, then that would indeed be a valid use of ALC for those
purposes, assuming it was set up correctly.
With the help of GOOGLE, I found a few references:
" As soon as a anomalous conditions is met (e.g. the reflectometer
reports a load mistmach), the controller develops a positive ALC
voltage to reduce the drive to a safe level." (
http://www.astrosurf.com/luxorion/qsl-amplifier-solidstate2.htm )
Note - most amps use negative now.
"The purpose of the ALC circuit is ..." "... to reduce drive when
the amplifier's protective subsystem detects an out-of-limits condition."
( http://www.ab4oj.com/quadra/sshfamp.html )
"Should the amp be loaded into a high SWR, the ALC will reduce the
drive level to a safer level." ( http://www.kk5dr.com/Tuneup.htm )
"most of the new series of solid state amplifiers hitting the
market these days, require the ALC to be connected as it is an
integral part of their built in self-protection scheme" (
http://www.eham.net/articles/10183 )
OTOH, many modern amps have built-in protection circuitry that may
not need the ALC connected.
Anybody can test their own amp by disconnecting the antenna
connector while driving it to full output ;-) . That is essentially
how I found out about how useful ALC can be I when I blew up my amp
when a flaky antenna connection went south while operating RTTY at
a full 1500 watts output years ago
Jerry W4UK
On 8/27/2012 12:11 PM, Jerry Flanders wrote:
Many amps rely on that ALC connection to allow them to cut back
on drive in the event of a malfunction such as an intermittent
flaky antenna feedline. A momentarily open/shorted antenna
could be very bad news for some amps under normal drive.
Some argue that you don't really need ALC. I suspect those guys
never had an antenna disaster.
Good luck
Jerry W4UK
At 02:52 PM 8/27/2012, ROGER SCHMITT wrote:
Have a small amp that I want to use on the 1500 but do not see
any ALC output to connect to the Amp, however since the
oiutput is only 5 watts, is this a problem? I intend to
connect the PTT circuit to the amp for on/off control.
Thanks for your help.
KY4RS
rogschm...@yahoo.com
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