Doug et al,
For a 700 watt output class amp I would go with a pair of 572Bs or a single
3-500Z. Both run close in cost. A new pair of Svetlana 572Bs will run around
$125.00, a new 3-500Z is close.
There are a ton of circuits available. I usually copy an already proven
circuit to some extent, eg, my HB quad 572B deck is a hybrid copy of the
AL-572 and Cliperton-L. I used many AL-572B parts, esp. the tuned input
cirucit parts. I found this much easier to do than waste time trying to
build my input pi network from scratch.
Given one choice I would go with a single 3-500Z with an Ep of 3200 to 3600
volts. Figure out what tube you desire OR what power supply component and RF
deck parts you already have and go from there.
This amp stuff is supposed to be fun. I enjoy the heated discussions. I
enjoy talking with Carl, Rich, and others. I especially enjoy Rich's web
page. He has truly done us a service and I admire all the hours he has put
in to put that data on the internet. What an assett (sp?).
I have not tackled a tetrode other than a 4-1000 deck I helped build with an
older ham friend here in SD four years ago. I do not like running 6000 volts
on a tube in order to get it to play.
See ya'
Lane Zeitler
KM3G
San Diego
John 3:3 <><
The Padres going to the world series was a fluke.
>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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>
>
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