[Elecraft] KPA1500 Power Level

[Bob McGraw]

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<jim at audiosystemsgroup.com>
To:elecraft at mailman.qth.net
Subject: Re: [Elecraft] KPA1500 Power Level
Message-ID:
	<43ba24ec-6da1-8c44-e0fc-ed878090a225 at audiosystemsgroup.com>
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
>