On Sat, Jul 10, 2021 at 10:36 AM jim.thom jim.thom@telus.net <
jim.thom@telus.net> wrote:
> Date: Thu, 8 Jul 2021 14:50:40 -0400
> From: <john@kk9a.com>
> To: <amps@contesting.com>
> Subject: Re: [Amps] FT8 power with the KPA1500
>
>
> <From an amplifier heating standpoint it probably makes very little
> <difference what power level you use with an Elecraft KPA1500. See the
> <Elecraft post on efficiency in the link below. I am not an amp guru but I
> <believe SPE Expert amps have different PA voltages which increases their
> <lower power efficiency.
>
> <http://mailman.qth.net/pipermail/elecraft/2018-August/259502.html
>
> <73,
> <John KK9A
>
> ### Per the link above, the KPA-1500 only makes 51.9% eff at 1.5 kw
> output. The german B26 amp is 70% eff at 1.5 kw.
The 51.9% efficiency appears to be worst case at 1500W output.
The efficiency of the KPA1500 (Pout / Pin) varies from amplifier to
amplifier and from band to band.
The same may be true of the RF-Kit B26, but I have no way to measure one.
If someone on this list does have one, please post numbers.
I just measured the efficiency of two KPA1500s at 1500W out on the six main
contest bands, and here is the result.
*Band* *KPA1500 A* *KPA1500 B*
160m 52% 59%
80m 60 60
40m 50 54
20m 60 62
15m 61 51
10m 66 67
73,
Bob, N6TV
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