[CQ-Contest] Contest amps under $1000
David A. Pruett
k8cc at comcast.net
Sat Aug 21 00:22:04 EDT 2004
At 10:16 AM 8/20/04 -0400, you wrote:
>What amps are out there on the used market fur under $1000 that are
>sufficient for contest service (i.e. occational high swr due to tx into
>wrong antenna at 3am, easy to tune etc.)
Reasonably reliable in contest service up to 1200W output or so (which is
roughly equal to the orignal 2000W PEP input). An extra muffin fan or two
to suck hot air out of the amp is a good idea. 120 VDC antenna relay is a
issue with modern radios.
>Similar to SB-220 except cost is higher - worth the extra 300-400$?
Agreed. The extra $$$ buys you 160M and little more.
No tuned input so SWR to radio poor on 15M/10M. As noted, tubes very
precious. Not well suited to surviving the "occational high swr due to tx
into wrong antenna at 3am". I own one of these, solely because it's a
great DXpedition/contestpedition amp (44 pounds).
I don't know whether you'll find the bandpass tuning all that useful,
unless you only operate where your antennas are matched very well. See my
comments later on 3CX400/800 tubes in general.
This is a 600W output amp in contest duty, period. Decent compact box for
DXpedition or mult chasing.
I have had problems using most of the 3CX400 (8874 and variants), 3CX800
and even the 3CX1500/8877 amps in contest duty here. They work great once
you're tuned up on a frequency - the problem comes when you QSY. Or, if
like me you have several antennas on a band. You tune up on one antenna
and everything is fine, then you switch another and BAM! the grid meter is
on the pin. If you have only one antenna on a band, it's not a big deal.
IMHO, the best value in contest amps right now are the Ameritron AL-1200
and AL-82 series. Both of these (plus the AL-1500) have the same case, HV
power supply, plate tank, etc. I owned an AL-1200 for five years before
selling it to my buddy W8MJ, and it never made less than legal limit with
100W drive, even with some loss from a bandpass filter. They have an AL-82
down at WP2Z which has seen a lot of abuse and damage, but when it's
running it puts out legal power with no fuss. Of course, these are
slightly above your target price.
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