[Amps] Any new tube research?

[Jim Thomson]

Date: Fri, 19 Aug 2011 19:05:55 -0400
From: "Roger (sub1)" <sub1 at 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