[Elecraft] QRO - KPA500 Failure

[Conrad PA5Y]

Hello Ed, I don't think that you are in class AB with 80% efficiency, in fact you cannot be.  Class B can theoretically achieve 78.5% but this is seldom achieved in practice, especially on VHF. Most likely there is a problem with instrumentation.

________________________________
From: elecraft-bounces at mailman.qth.net <elecraft-bounces at mailman.qth.net> on behalf of K9MA <k9ma at sdellington.us>
Sent: 11 February 2020 17:11
To: elecraft at mailman.qth.net <elecraft at mailman.qth.net>
Subject: Re: [Elecraft] QRO - KPA500 Failure

That's very high efficiency for a solid-state amplifier. Are they
operating in class C? Are there any IMD specs at those output levels?

73,
Scott K9MA



On 2/11/2020 03:18, Edward R Cole wrote:
> I checked the operating specs on two of my QRO amps.  Not a KPA500.
>
> 2m-1500w PA using a MRF1K50 in class AB:
> 945w  1398w dc  67% eff  453w disp
> 1511w  1888w dc 80% eff 377w disp
>
> 2m-1200w PA using a MRFE6VP61K25H in class AB:
> 566w  1200w dc 47% eff 634w disp
> 1133w 1542w dc 73% eff 409w disp
>
> less heat dissipated when running full power RF ouput.
> Both are W6PQL amps.
>
> 73, Ed - KL7UW
>   http://www.kl7uw.com
> Dubus-NA Business mail:
>   dubususa at gmail.com
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--
Scott  K9MA

k9ma at sdellington.us

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