[AMPS] 811s, small amps, cheap amps, etc

Doug Person Doug Person" <w4dxv@ibm.net
Thu, 29 Oct 1998 09:57:51 -0500

Whew.... What a pileup.  At least on this reflector you can count on
receiving a few opinions.  First, lets get a few things straight. I've been
in Ham Radio since 1961.  So I've been around the block a few times.  I
write articles and build many, many experimental antennas.  This, I'm good
at.  I wasn't advocating putting 572b's into an 811 amp and driving it hard.
I was simply asking whether their was any benefit to be gained.

Building amps, as much as I'd like to give it a whirl, seems filled with
numerious technical complexities. Many of which   are part of the on-going
debate on this reflector.  Actually, I've bought and read several books,
many that were recommended by folks here. I'm still not sure its something
worth investing time and money into, as much as I would dearly love to build
the amp I'm thinking of.

A lot of you guys are involved in electronics or have spent many years
learning the skills to do this sort of thing.  I experience a deep sense of
awe when someone discusses their 1.5KW+ 4CX1000 amp. I am sincerely
impressed.  I continue to read this reflector because it is one of the few
(along with rec.radio.amateur.antennas) that consist of people who really
know what they are talking about.  Even the heated debates are interesting.

My experience with Ameritron amps covers a few models that I bought and
traded for used.  I have always been able to resell them for little or now
loss of capital from the ROF account. (Radio Operating Fund).  What I
disliked most about them, other than their modest quality, is they always
seem fussy to tune, making band changing an annoying sequence of dial
twisting to get the amp tuned right.  Maybe this is just how tube amps are.

One of the better amps I've owned was a Clipperton-L.  Didn't seem so fussy
and cranked out 800-1000 watts without complaint.  But, I wanted a 3-500
amp. I got the AL-80B.  It seemed to run hot enough to warp the cabinet.  I
had arcing problems so I learned to live with 700 out and tune carefully.
It wasn't a satisfying experience.

My first and oldest amp is the Clipperton GLA-1000B.  Still the original
tubes.  Tunes up in a flash and gives me a one 'S' unit boost when I need
it.  Plan to upgrade it to Svetlana EL-509s in the near future.  It's a
concept that I find intriguing.  Small, inexpensive and effective.  At least
in its day.  500-600 watt amps are entry-level and generally inexpensive.
And this power range also can make a big difference in operating
effectiveness: 100 to 600 is a 1 to 1.5 'S' unit increase in signal
strength? Enough to make or break many, many contacts.

So my thoughts are: what would an optimized, small, reliable, easy to use
and relatively inexpensive amp be?  I was thinking of a Svetlana 4CX400A.
Should be capable of 600+ watts.  It's small.  Could the whole amp and power
supply be built into a modest-sized cabinet?  Could such an amp be designed
such that people like myself of modest technical skill and knowledge could
complete it and receive the fine sense of accomplishment,etc of the project?

Doug -- W4DXV

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