Those resitors from Latronics look really interesting! I never thought of
making a water cooled dummy load. Would that be considered an alternative heat
source then??? hi hi... I wonder what the costs on those would be...???
The ohmite resistor look nice too but I see that it says they are a
wirewound-type and they don't give them away. I would almost be better off
finding a box of 5 watt resistors and having a soldering party.
The Palstar are nice dummy loads and I've considered getting the 5k unit, but
bring your check book unless I could find one used somewhere...
Dave
kb8nnu
________________________________
From: Jim Thomson <Jim.thom@telus.net>
To: amps@contesting.com
Sent: Fri, February 19, 2010 7:56:51 AM
Subject: [Amps] kw dummy load resistors.
Date: Thu, 18 Feb 2010 23:08:44 -0700
From: John Lyles <jtml@losalamos.com>
Subject: [Amps] kW dummy load resistors
Two sources of non-inductive high power tubular resistors:
Cesiwid, Kanthal-Globar or whatever they are called now (used to be
Carborundum Co). They make resistors that are about 300 watts rating,
that can be series or paralleled for 50 ohms and are made from bulk
carbon-like material.
Altronics Research, in Arkansas. They make very high power deposited
film resistors on ceramic cores. Bird uses them in their loads.
If you want to make a good load, these are some of the best. Bring money
though.
73
John
K5PRO
### Globar has type SP... up to 1000 W CCS, convection cooled.
2" diam x 24" long. The applications engineer lady at globar tells me
that if immersed in oil, CCS diss can be increased by 2-5 X. Normally
2 X is ok, with just a lot of oil... and for more diss, the oil has to be
circulated through an external air cooled radiator.
## SP types are glass bodied, inside and outside, and suitable for
oil immersion.
## I opted for 4 x 1" x 12" long, 275W [200 ohm] globars in parallel.
Each resistor sits inside a 12" long x 2.875 OD", sched 40, AL pipe.
[ all 4 x pipes are heliarc welded.] Entire mess sits inside 7 x US gals of
oil, non-circulated... with a 7-16 Din connector. So far, so good.
## the resistors the other fellow's mentioned on the Mouser site are
INDUCTIVE, and may well not work on HF !
## BTW, I have several old globar TYPE CX 200 ohm/275w resistors
that are in air cooled loads. They can NOT immersed in oil. They are NOT
glass bodied types. Globar tells me the old CX types were made back in the
60's. Air cooling only, on those things. If in oil, they will absorb oil, and
resistance will RISE. Yes, bring money, lots of money. The palstar
load is good. Each resistor is 12" long x 2" diam. Dunno if their resistor's
can be immersed in oil or not. Globar does NOT make a 12" x 2" diam
resistor, too bad, only 24" x 2".. and also 18" x 2" .
http://www.globar.com/ec/bulk-ceramic-resistors/tubular-resistors.html
Later........ Jim VE7RF
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