I've said this for years, even with tube type amplifiers. One
exception, to which I'm aware, is the Johnson Thunderbolt which uses a
variable L along with variable C for the input components to the Pi L
network. Otherwise, the Pi network input circuit is using a fixed
value of L and a variable C for the frequency. Thus it is designed to
match the output device Z only at rated power.
I've performed power measurements on my KPA500 on all bands at 100
watts, 200, watts, 300 watts, 400 watts, and 500 watts output.
Measuring input power and output power and calculating efficiency,
dissipation, and gain on all bands, 160M - 6M.
73
Bob, K4TAX
Message: 5
Date: Thu, 16 Sep 2021 20:26:44 -0400
From: Steve Hall<[email protected]>
To:[email protected]
Subject: [Elecraft] Subject: KPA1500 Power Level
Message-ID:
<calduqnpgsbb7iplrzl8goye7fxc1hqwak-jekipkkzu1zrn...@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"
I looked at the link given in part of this discussion regarding efficiency
and dissipated power data at various output levels. Very revealing.
During a recent virtual hamfest I spoke to the Elecraft designer of the
KPA1500 and he confirmed that the heat dissipated remains nearly unchanged
whether you are running 500 out or 1500 Watts out. If owners of the
KPA1500 reduce power output to "go easy" on their amp by reducing power,
they are not.
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