Date: Fri, 19 Aug 2011 19:05:55 -0400
From: "Roger (sub1)" <sub1@rogerhalstead.com>
Subject: Re: [Amps] Any new tube research?
On 8/16/2011 2:01 PM, John Lyles wrote:<snip>
> As a designer of power amplifiers using both tubes and transistors, I
> see a good trend in solid state, with 1200 watts or more per device. But
> I don't expect to see a megawatt in a device, something that I can and
> do see with new tubes. Ham radio will eventually quit using tubes except
> for nostalgia reasons;
I really don't see wide adoption of SS legal limit amps until the
devices can be made more rugged, can be cooled more easily, and become
available at much lower prices. Prices are based on tooling set up
costs, number of units produced per batch, amount of silicon in the die
compared to the base wafer size, and yield efficiency. At present they
are just too fragile and the protective circuitry (which is more
complicated than the amp) really pushes the prices far too high for wide
spread adoption.
Except for quite expensive and complex amps (or medium power) I really
don't see solid state amps becoming wide spread. 800 to 1000 watts
seems to be the current limit or dividing line between the high priced
spread and the rest of the pack.
## I looked at a buddy's 1kw CCS commercial marine SS amp... and it was
the most complex thing I have laid eyes on [2-30 mhz]. 4 x RF modules, with
4 x mating power supply's. Then the usual mess of combiners, then complex
control
and protection circuits. My FT-1000D is easier to work on, and figure out.
## My problem with these SS amps is the eff on all of them sucks. 50% isn't
good, and that's only when they are run at full bore. Reduce the power output
a bit, and presto, ur now down to 36% eff. Heat generated stays the same!
TX imd is nothing to write home about either.
## another buddy had am Icom SS amp, VERY expensive. It had just gone out of
warranty, when
he had a spike come in on the 240 vac line....which took out EVERY transistor
in the amp. The repair
bill was gawd awful. By using groth type, or similar turns counters for both
my vac tune + load caps,
I can switch bands.. like from 16-15m, in 45 secs flat. Just set the turns
counters to the logged
pre-sets. One setting will easily cover 14.100 to 14.300 on both a
3CX-3000A7 and a 3CX-6000A7,
plus most other bands. None of us will ever be able to afford a SS 5-12 kw
pep output cw/ssb amp in our
lifetime's.
### Almost forgot something. These SS wonderbars also require the mating 2-10
kw, full automatic ant
tuner's...so they don't blow up in your face. Most of em don't appear to enjoy
operating into a 2:1 swr.
## I can see a place for SS amps up to maybe 500 w out...and with mating
switching type supply's and also
the requisite mating auto tuner, and clean IMD. [which usually implies sky
high idle current, low eff, loads of heat, etc]
Later... Jim VE7RF
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