Based on personal experience and observations with another ham radio
brand and company, it is most often the case that power overshoot is
likely to occur when the transceiver is operated at reduced power.
Namely to drive a power amplifier. In general, tube amplifiers are
more tolerant than solid state amplifiers. Tube amplifiers in general
have a soft power ceiling. The overshoot occurs on the first CW
element or SSB spoken word. It takes a fast and triggered scope to
observe this. In these radios the ALC us used to control output
power. Until the internal ALC, based on its time constants of attack
and release gets its control routine established and is allowed to do
its job, the power can soar to near maximum output.
Yes, the radio that Jim mentioned has been observed by me to have a
notorious amount of CW clicks and SSB splatter. Otherwise, great
receiver, lousy transmitter.
73
Bob, K4TAX
Message: 14
Date: Sat, 18 Sep 2021 19:15:51 -0700
From: Jim Brown<[email protected]>
To:[email protected]
Subject: Re: [Elecraft] KPA1500 Power Level
Message-ID:
<[email protected]>
Content-Type: text/plain; charset=utf-8; format=flowed
For a long time, W8JI, who has designed ham power amps, has observed
that some JA rigs have this problem. And for a long time, the mfrs have
failed to fix them. Just like they have taken decades to fix clicks, and
at least one (Yaesu) has been building rigs with lots of splatter on SSB.
73, Jim K9YC
On 9/18/2021 6:46 PM, Jerry Kirshenbaum wrote:
re: it'd pay to review the SPE
In May 2021 I bought a SPE 1.5K-FA 2nd generator new from the distributor in
Texas. I?ve been using a SunSDR2 DX 100W transceiver while I wait to receive my
K4D. The 1st time the finals blew may have been operator error. Subsequently, I
discovered that the software allows one to limit the power on each band. So I
set the SPE to mid power (it has low, mid, high settings) and determined the
correct output for 700-800W. That left at least 20% head room. Despite this
seem lying failsafe procedure, the finals blew again. The distributor would not
cover this under warranty on the grounds that my radio has spurious spikes
which blew the finals. In fact, if you run the ?wrong? radio with this amp, you
don?t have any warranty because the radio is indicted as the cause of failure
sight unseen.
The amp when it works is wonderful. One case, 24 lbs, very quiet. I had
everything linked together with my SteppIR DB18E through DxLab.
Two times back to the distributor for repair in 3 months was enough. I sold it
and now have a KPA1500 which is working great.
BTW, the distributor also says the IC-7300 (my backup) has spurious spikes as
well and presumably is another transceiver not covered under their warranty.
73, Jerry / K0ES
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