Metal-film and metal-oxide resistors are commonly done as a spiral
like the carbon film ones you describe. It's possible to find RF
metal film resistors which are relatively non-inductive, but clearly
the spiral ones will have an inductance about the same as a coil with
the same dimensions and number of turns. OTOH, that may not be a
problem--see example below. 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. As they say, your results may
vary. But in any event, if you can use the resistors you have to make
a 50-ohm load and have a 50 ohm SWR meter you trust, you can get at
least an idea of their performance at RF.

Cheers,
Tom

(Example: say you have a 100 ohm metal-oxide resistor which is a
four-turn spiral 0.25 inches in diameter and 0.5 inches long. Its
inductance will be about
40 nanohenries, which less than j8 ohms at 30MHz. As a non-precision
load, that probably won't be an issue at all.)

(SpamHog) wrote in message . com...
I shredded a few carbon resistors and noticed that many have the
carbon layer laid out in a spiral pattern around the cylindrical core,
up to several turns.

I also shredded a few metal-film ones, but could not figure is the
metal was on a single layer or not, and how it was connected to the
leads.


I wonder which best approximates a non-inductive resistance.



Do "spiral" carbon resistors have a significant inductance?

Do all metal-film resistors have a single layer, or are there some
multilayered or (G_d forbid!!) spiral-layered, with plentiful
capacitive bypass???



I have found a set of 16 x 100 ohm / 2W metal-film resistors which I
am ready to assemble them into a 400 ohm / 15W (derated) terminator
for a T2FD, but I'll wait for advice...


tnx de n1jpr/i2
filippo
http://filippo.ru.ru