Homebrew 1KW Wet Dummy Load - HomeBrew Forum at eHam.net

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eHam.net Forum : HomeBrew : Homebrew 1KW Wet Dummy Load

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RE: Homebrew 1KW Wet Dummy Load	Reply
by NO6L on September 6, 2008	Mail this to a friend!
I know this thread is very old, but MFJ now sells "Globars" in a few values with one 50 ohm one at 200W. They are not expensive, either. You should also install it inside a 2" metal tube vertically to aid in heat transfer and oil circulation. You can use mineral oil from drug stores or if you want to build a couple of these use Texaco turbine oil. It's the same stuff with corrosion and rust inhibiting additives and is cheaper in larger quantities. If you really want to increase the power handling, stack two one gallon cans, submerge the resistor half way down a longer tube and feed it with coax

RE: Homebrew 1KW Wet Dummy Load	Reply
by KC7NOA on October 23, 2009	Mail this to a friend!
I have a Para Dynamics PDC-DL50, ITs a 100W dry dummy load. I have used these before in oil and now that i have need for a 1KW load again ill submerge the last one of these that i have in oil... KC7NOA

RE: Homebrew 1KW Wet Dummy Load	Reply
by KG4RUL on October 23, 2009	Mail this to a friend!
$70.00 for an MFJ oil filled dummy load.

RE: Homebrew 1KW Wet Dummy Load	Reply
by W6RMK on October 25, 2009	Mail this to a friend!
A previous post mentioned "real carbon Globar resistors." Those aren't carbon, they're Carborundum (a trade name for silicon carbide), made in electric arc furnaces by, oddly enough, the Carborundum corporation, with electricity coming from Niagara Falls (one of the first industries to use hydro power). It's really hard (Mohs 9) so it's used as a commercial abrasive. SiC has a very high temperature limit, so it's used for thermal elements. It's also used for dummy loads and absorber (as for anechoic chambers) in vacuum chambers, because it doesn't outgas. They also make ceramic non-inductive resistors with a thin film of SiC. The core is a ceramic tube, with a thin layer of the resistive material, often with silver plated ends. These are used as dummy loads for RF, in pulse discharge apparatus, etc. The names have changed over the years, Carborundum became Cesewid, then Sandvik, now a division of Saint Gobain abrasives.

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