[Elecraft] KPA-1500 wish list

[Doug Turnbull]

Dear OMs and YLs,
     Why not just run 1400 Watts.    The difference in power will never be
noticed by anyone you are working.    It should reduce stress on the KPA1500
components.   Though feedback which is after all what we are talking about
can not only reduce distortion but in some instances introduce distortion;
ALC being just one example.   If your SWR forces the return power to over
200 Watts then it seems to me there is the more important problem to
address.

     I am sorry if I have stepped on any toes.   This is not my intent.    I
too run a KPA 1500 which is a delight.

                   73 Doug EI2CN

-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Rick Tavan
Sent: 18 November 2019 17:45
To: N4ZR; Elecraft Reflector
Subject: Re: [Elecraft] KPA-1500 wish list

I'd love to have something like this, Pete!  It's not only frequency
excursions that cause output fluctuations but also warm-up. The gain of the
power transistors is temperature-sensitive. I'd like to be able to set a
target output power (typically 1500w but maybe less on bands with
mismatched antennas or in countries with lower power limits), have
*something* monitor it, and send drive adjustment commands to the K3 via
sharing the serial port. (The commands exist - PC and PO.) It's not the
same as AGC which is analog and real-time and can cause distortion. I've
called it "Slow AGC" because it would only operate every second or so,
perhaps taking multiple cycles to recover a desired output power and
causing no measurable distortion. It would essentially duplicate what we do
manually - keep a sharp eye on the power and tweak the K3 PWR control
appropriately. That's not only a significant drain on brain and muscle
cycles over the course of a long operating session as in contesting but
also useful in less extended situations like the excitement of a DX pileup.
It would require software in the KPA1500 and maybe also an external box or
computer where port sharing would take place. (It could also be done
entirely external to the KPA1500 by replicating its power sensing
circuitry, a bit of a waste.) It's not trivial but I'm convinced it's
possible.

73,

/Rick N6XI

On Mon, Nov 18, 2019 at 8:31 AM N4ZR <n4zr at comcast.net> wrote:

> Here's one that I kept running into.  My K3/KPA-1500 when operating at
> one end of the band on 40 and 80, would work fine, but when I went to
> the other end  I found that often I would be running over 1500 watts,
> and sometimes, the result would be reflected power exceeding 200 watts,
> causing a fault.  For those of us who have the Aux port cable connected,
> wouldn't it be pretty simple for the KPA-1500 to turn down the K3's
> power to limit output to 1500 watts?
>
> --
>
> 73, Pete N4ZR
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>
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-- 
--

Rick Tavan
Truckee and Saratoga, CA
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