Its those little things that bite you on the a**.
Been there done that and is why I bought a 3000 W CCS RCA load, built by
Bird, with a tapered snout and rated to 1000 mc at a hamfest almost 30 years
ago.
It included a seperate 5" wattmeter in a cabinet, and a set of 250 and
1500W slugs for the 400-1200mc range, total of 4 elements. It works fine at
1296 with barely a tickle of VSWR and is still useable at 2304.
All for $125 since others passed on it as they werent intelligent enough to
realize it works fine at VHF and below also (-; This was even before no
coders and make believe Extras !!
The resistor is still within 2% of 50 Ohms and based upon the mc ratings it
has to built before the pointy heads forced that EU crap on us. I do turn on
a pair of larger size muffin fans when pushing or exceeding the 3KW.
Carl
KM1H
----- Original Message -----
From: "Vic K2VCO" <k2vco.vic@gmail.com>
To: "Amps reflector" <amps@contesting.com>
Sent: Saturday, November 09, 2013 11:19 AM
Subject: [Amps] Screen current problem solved!
Yesterday I reported that the screen current of my 4CX1000A was dropping
when the key was down for more than 10 seconds or so. Several of you
suggested that some component in the tank circuit or screen supply was
heating up.
Well, I found it. The dummy load! Sometimes you don't see the nose in
front
of your face. I have a dummy load which is a Drake '1000-watt' unit that
I
added several muffin fans to. I guess the fans weren't cooling it fast
enough -- the actual resistor element is rated at 500 watts -- so it was
heating up, changing in value, and therefore changing the loading.
--
Vic, K2VCO
Fresno CA
[1]http://www.qsl.net/k2vco/
References
1. http://www.qsl.net/k2vco/
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