All,
IMHO the problem with today's 100W radios is that they are designed for
12V finals. Comparing a "modern" solid state radio designed to run on
12V finals to a Collins 32S-3 is borderline ridiculous. There is a price
to be paid for "no tune" and using 12V finals makes it worse.
If I was designing a final section for one of these rigs it would be a
pair of 50V MRF-150's derated to 150W max out. They're plentyful,
comparatively cheap, probably close to a matched pair of 6146B/W's for
TS-520.
Of course there are going to be people who are unhappy not being able to
run the rig "all knobs to the right", to the max of a pair of
MRF-150's...300W, but too bad. Buy someone else's rig.
I'd bet a final section built and run like that would hit -40 IMD
running full tilt boogey. Add a little pre-distortion and we'd hit -50dB.
The days of the 12V SSPA in rigs are numbered, or should be.
So... that leaves me with a rig that will do -45 to -50 IMD and an amp
(AL-1500, Ameritron's number) that'll do -38. Hmmmm.
Let the anecdotes fly.
On 5/10/2017 11:17 AM, Manfred Mornhinweg wrote:
Jim,
## The 100w K3 driver section is junk, both the driver and the
main 100 watt pa need a serious re-design.
What exactly would you improve in that design?
I just had a look at those schematics. The driver section looks pretty
OK to me, while the 100W amp suffers from a typical design flaw that
also affects most other 100W radios from the last 20 years or so. But
it's really not easy to avoid that flaw!
I would be interested in seeing your suggestions for improvement, to see
whether or not they agree with my own.
Calling that design "junk" seems a bit over the top. It's no worse than
many others. In fact better than some...
Can you point me to some 100W broadband amplifier stage that you would
consider good? And some 10W driver that you would endorse, and why it's
better than the Elecraft "junk"?
Manfred
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R. Kevin Stover AC0H
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