"DoN. Nichols" wrote:

On 2013-03-20, Lloyd E. Sponenburgh lloydspinsidemindspring.com wrote:
Gunner fired this volley in
:

Anyone got a 50 ohm, 100 watt dummy load collecting dust I can
swap/trade for?

An incandescent lamp isn't perfect, but works.

Even better -- mount it in a gallon paint can, with a good RF
connector in the lid -- and oil inside to carry the heat from the lamp
to the walls of the can for cooling.

The higher the frequency, the more that lamp will differ from
the proper impedance -- with all those little curly Tungsten wires as
the filament. But the can will at least keep the RF from radiating.
The main risk with a poor impedance match would be damage to the final
of the transmitter.

Anyone ever have a Heathkit "Cantenna"? Was it an array of
carbon resistors in oil, or an incandescent lamp? The former would be
more constant impedance, at least.


Don, they used a 200 watt 50 ohm carborundum non-inductive oil
treated resistor immersed in transformer oil.
http://www.orcadxcc.org/content/cantenna_va7jw.pdf


--

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