Improvised power resistor

Nah..It's just a test load.. If it decomposes,I just buy another.. I use tap water here..It's low enough in ions that it's no where near the resistor conduction.. A little electrolysis is tolerable if it takes a long time to erode the metals.

D from BC

On a sunny day (27 May 2007 19:32:59 -0700) it happened Winfield wrote in :

If you place it in a diode bridge it should sort of work for AC too. (if voltage is high enough).

I once saw a construction project for an RF dummy load using a pile of 1/2W or so carbon resistors and stiff wire. The end result was about the size of a cantenna element, and of course the guy ran it in oil.

The resistors were in groups that were arranged radially around the center conductor, and there were wires along the length for the outer conductor.

Cheers! Rich

It's a bit of a mission, but I know somebody who took a nice straight stick, wrapped it in foil and left it in a fire for a while. The stick became carbonised and ended up like the old "body-end-dot" carbon resistors. I recall it being a bit hit and miss to get the correct value.

Barry

In air, those large hollow ceramic tubular resistors (with zig-zagged "flat" wire) are good to where they glow orange, just before the ceramic glaze melts...

On May 28, 12:08 pm, Rich Grise wrote: [....]

I've seen the same sort of thing except the center conductor was also a string of resistors. The ground was a cage of soldered #14ish wire. It looked a little like a steel tower design. I suspect that the design of the outer was more for mechanical reasons than anything electrical.

Actually, in the article I read - in QST or something, IIRC - the outer shape actually was electrical - and the inner conductor also had cones or frusta end-to-end - the cone-shaped parts are coaxial impedance transformers. This apparently lets you use bags of surplus resistors and tailor the physical design to what's available.

Cheers! Rich

This runs along the active load lines, build a generalized immitance converter with power operational amplifiers. The circuit is even parametrically controllable for parasitic inductance and capacitance. The choice of amplifiers will control the voltage, current, and power capabilities.