This all good stuff, I elaborate below:
about:
### 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
========================
K2LB adds, that I used the globar 50 oohm resistor, but cooled it with
tap water in a big bucket. Vswr too far from 50 ohm, so measured about
30 ohm with simpson meter. I removed the resistor, and found the
reading then high, but 75 ohm or so. I added 1 teaspoon sault, and it
was close to 50 ohm, at least enough for me to see the 10 KW, of a
commercial transmitter. We used this for a mounth before could buy the
"real" load. This type of load was useful several times, but I found
that if it is a 5 gallon tank, and about a foot of #10 wire probe that
the salt-water would boil around the wire with the bubbles making a
jumping load. This was at 10 kw, but I can't think of anything cheaper
aned usable for a KW!!!
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