[AMPS] 811s, small amps, cheap amps, etc
km1h@juno.com
km1h@juno.com
Fri, 30 Oct 1998 03:38:16 -0500
On Thu, 29 Oct 1998 19:57:39 -0800 zeitler@ibm.net writes:
>
>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.
Lane, Doug, et al.
These 12-14 hour days are a real pain...but it is the end of the month
and the Prez wants to see RF out the door and not on the bench. Sorry if
my responses are somewhat less than timely! Right now it is 3:41 AM.
Doug, the Svetlana 4CX400A is a very nice tube and widely popular from HF
to UHF.
A BIG problem is that you still have to use the Eimac/Johnson style
sockets at RF since the Svetlana socket is just about useless except for
a modulator.
Good sockets cost big bucks when purchased new so a commercial version
would probably not be economically wise. Flea market sockets are dirt
cheap and the 4CX400 wold be a nice home brew project....just keep the
drive down to below 10W unless you run a big pad in-line.
For a few bucks more the Svetlana 4CX800A and its good RF rated socket
would be a better choice. Easy to get a KW plus from a single tube.
Tetrode caveats still apply!
The relatively low Ep does make some tetrodes very attractive when
considering the tank circuit component cost AND availability.
Please...check out the G3SEK web page for a great screen regulator
circuit....beats all the others by a wide margin.
73 Carl KM1H
>
>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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>>Problems: owner-amps@contesting.com
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>>
>>
>
>
>--
>FAQ on WWW: http://www.contesting.com/ampfaq.html
>Submissions: amps@contesting.com
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>Problems: owner-amps@contesting.com
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>
>
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