Date: Fri, 15 Jun 2012 22:20:11 -0400
From: "Carl" <km1h@jeremy.mv.com>
Subject: Re: [Amps] Dummy Load Blues
Some of those BCB DL's can barely make it to 160...such as the ones in the
Gates BC-1n series.
## A fellow across town collects broadcast stuff. All his dummy loads used for
AM 550-1600 khz use... are all the same. They look like the heater ele found
in
a cloths dryer. NICHROME ! Its in an open frame thingy. It comes with a
huge
variable cap + fixed parallel cap padders. The variable cap is used to tune
out the
XL of the dummy load..leaving just 50 ohms and zero reactance. You gotta
tune
em for flat swr on a given freq. AM TX is no big deal... they are stuck on
one freq.
and never qsy. Ur right, they barely make it up to 160m. They also barely
maake it down
to 550 khz too. padders have to be added-removed, so the variable cap is in
its sweet spot.
I said no thanks..and just built my own..using 4 x 200 ohm globars in parallel.
each type
SP globar is 1 inch diam x 12 inch long. I used 4 x 12 inch long aluminum
tubes.. sched
40..and 3 inch diam..and had em heliarc welded together. One resistor down
inside each al tube.
Then the entire mess goes into 7 gals of xfmr oil...with a 7-16 din
connector. its just a
heath cantenna on steroids ! each of the 4 x resistors is rated for 275 w
ccs in air. Sits
on a dolly..that rolls around the basement. I gave up on water cooled loads
for now.
hb salt water loads will also work good.
Jim VE7RF
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