Lots of useful replies - thanks to you all !


Dale W4OP:
Your best bet for low inductance would probably be the carbon
composition
...they look like a perfect cylinder- no bumps on the ends.

Understood! I remember popping resistors that contained a blackish
compound throughout the cylindrical body: I assume those were cabon
comp.

Also, correct me if I err, they tended to be LARGER that similarly
powered resistors that had their heat-generating portion right under
the skin.


Dave Platt )
Or use one of the low-inductance metal-film/metal-foil types.
and Tom Bruhns )
Metal-film and metal-oxide resistors are commonly done
as a spiral like the carbon film ones you describe.

I am satisfied that metal film/foil types do not come in
rolled-up-foil geometry like some capacitors. This is good - no
capacitive bypass. Also, avoids the same temperature gradient / heat
dispersal issues of carbon comp.

OTOH, still no guarantee that a metal film resistor is non-inductive.


Cecil Moore )
I have some non-inductive wirewound resistors. They
simply reverse the direction of the winding every
so often to obtain canceling fields.

I knew they existed, and saw them in catalogs, but never used them.

I have been tempted to use a high power, low resistamce inductive WW
resistor as a coil in a regen receiver, just to see how well one can
compensate for losses.... I bet both regeneration and tuning will be
VERY smooth


Tom Bruhns )
I've put a couple 100-ohm 2-W metal-oxide resistors
in parallel, with very short leads, and tested the
combination for return loss and found it to be better
than 20dB r.l. (1.22:1 SWR) out to beyond 150MHz.

That pretty much cuts it!

I can easily test my 16 x 100 ohm resistors as a couple of 50 ohm
dummy loads on HF. After all, a decent HF match is all I really need,
and chances that a low "random" SWR will result if great reactance is
added atop resistance is quite modest. Thank you for pointing out the
obvious to my obviously obnubilated mind!

Filippo
N1JPR/I2
http://filippo.ru.ru