All good valid points that you make here Kevin.
There is also an equal fascination / obsession in some ham radio quarters
with IM3 and levels! We are talking here of HF amateur / ham band
transmitters NOT professional transmitters where spectral cleanliness is
more important.
It's the higher order IM stuff / crud that has to be curtailed...
The modern trend towards Adaptive pre-distortion techniques works well to
clean up mediocre PA transistors and sort of turn a sow's ear into a silk
purse.
Leigh
VK5KLT
-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Kevin Stover
Sent: Friday, 22 May 2015 10:28 PM
To: amps@contesting.com
Subject: Re: [Amps] SPE 2K RTTY Duty Cycle
There are NO 12V final amateur transceivers that make -40dB IM3, none. Never
have been, never will be. The best are at -33 to -35.
Those transceivers capable of 200 Watts are all usinng 28 or 50V finals and
can reach -40 depending on the low pass filter used behind the PA.It's time
for the manu's to get rid of this fascination with running everything off a
battery.
The most expensive part of any SS amp is NOT the finals themselves it's the
LPF that will take 1500 watts and keep harmonics legal (-43db HF, -60dB 6m).
That's not IM3. Name the amp that hits an IM3 of -40. The 8877 will come
close, the Russian triodes won't, none of the tetrodes will do it.
--
R. Kevin Stover
AC0H
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