[Amps] The cost of amplifiers, radios
Paul Baldock
paul at paulbaldock.com
Tue Dec 6 00:31:54 EST 2016
My main amp is an ACOM2000A. But when I need instant on for a QUICK
qso I use my backup amp the L4-B. I run 3400V on the plates in the
L4-B and comfortably get 1500W on SSB and CW. I have the original
cooling fan, so I do not use it for RTTY.
I have no interest in cheating and running more than the legal limit.
By the way for those that don't know, our legal limit on 30M is 200W PEP.
- Paul KW7Y
At 09:04 PM 12/5/2016, Jim Thomson wrote:
>Date: Sun, 4 Dec 2016 16:27:18 -0500
>From: "Mark Bitterlich" <markbitterlich at embarqmail.com>
>To: "Bill Turner" <dezrat at outlook.com>, "Amps group"
><amps at contesting.com>
>Subject: Re: [Amps] The cost of amplifiers, radios
>
>
>Bill,
>
>The Henry 8K does 160, and all WARC bands. Of course it is also pretty
>expensive and out of production. Also very heavy, but you can remote the
>power supply and RF Deck from the operating position by quite a distance.
>And yes, it has a loud fan. Just my own personal opinion, but I believe the
>tube it uses (3CX3000A7) is actually one of the best on the market .....
>cheap for the power it develops.
>
>You are correct, the majority of the other models do not do 160, and use
>individually switched Pi Input "modules" that make operation on some of the
>WARC bands less than a "plug and play" operation, not to mention the tapped
>coil(s). Still, they are pretty amazing amplifiers. Just saw a Henry 5K
>Classic for sale for $3000. Two 3CX1200A7's (sadly, now a pricey tube), but
>it will also put out serious power.
>
>I really like the idea of cheaper amps with one pre-set for each band,
>(common parts, etc.) but logistically hooking them all up to one exciter
>would tend to be a PITA.
>
>Obviously I own an 8K and enjoy it very much. I have tuned it into a 4.5:1
>VSWR on 160, with 1500 watts out on CW to work Navassa (an 80 meter OCF, was
>all I had at the time!). Worked perfectly. No computer controllers
>protecting it, so if you get REALLY stupid, you let the smoke out.
>
>Mark
>WA3JPY
>
>## The 3CX-3000A7 tube used in the 8K and other amps is a superb tube.
>IMD3 is -59db pep...at 5 kw pep out..and more and lower power levels.
>Instant on, rebuildable tube. 50 ohm input. 225 w CCS
>grid dissipation, and even more when in GG mode, with grid bonded to chassis.
>You can use the grid as a dummy load for a FT-1000 D. With 5 kw
>out, the grid
>only dissipates aprx 80-90 watts. Nobody ever blew the grid out of
>a 3x3 tube,
>even 11m ops.
>
>The henry 3K ultra is also a 160-10m amplifier.
>
>## typ 3CX-3000A7 in GG with 4800-5000 under load runs as follows.
>50w in = 1.5 kw out.
>100w = 2.5 kw
>150w = 3.5 kw
>200w = 5.2 kw
>
>## the 3CX-3000A7 is still used in a lot of FM broadcast TX, like
>energy onxix..and others.
>
>## using several small amps, each tuned on a different band is
>simple in most cases. I string
>all 4 of my L4B amps in series, nose to tail. Then either tune each
>amp on a different band, or
>cw + ssb on the same band, or cw and 2 x ssb segments, like for
>80m, or any possible combo
>you can imagine. Low bands at night, high bands during the daytime etc.
>
>## That works, provided the amp in question will handle full power
>on BYPASS mode.
>
>## I use a simple rotary switch, to switch the key lines to each
>amp. IE: keyline from xcvr to
>input of rotary switch. Then 1 output to each amps key line, so 4
>in all on the output of the
>small rotary switch. Then only one amp can ever be keyed at any
>time. Dead simple,
>and effective. If one amp ever blew up, I still have 3
>spares. Modifying a drake L4B to
>include 160m ( in addition to 80-10m) is not an issue either,
>fairly Simple really. The oem
>156 uh plate choke is ample for 160m, as is the oem Bifilar fil choke.
>
>Jim VE7RF
>
>
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