To: <amps@contesting.com>
> Date: Wed, 27 May 1998 10:36:12 -0400 (EDT)
> From: km1h@juno.com
> Subject: Re: [AMPS] More amplifier experiments
> To: amps@contesting.com
> I seem to recollect suggesting the new 5W metal oxide resistors from
> Mouser more than once Jon.
> They are cheap and you can buy several values to experiment.
> Are they inductive....not that I can measure on either a hand held LCR
> meter or an old Tektronix 130 LC Meter. My HP-4271B has died. In any
> event they seem to function fine in suppressor circuits up thru 50MHz.
The 5 watt metal oxide resistors I have sampled from Mouser are very
inductive. Not only that, you have NO control over who's resistors
they send you.
If anyone knows of a non-inductive 5 watt standard off the shelf
resistor let me know....I've been looking for one for years.
> And...yes, not all 2W "carbons" are non-inductive. I bought several that
> went bang on me. Turns out they used what appears to be resistance wire
> wrapped around a small carbon core. The only true carbons that I know of
> are the Allen-Bradley ones that carry the Mil-Spec designation.
The keyword is "composition" type carbons. Carbon films and
conventional carbons use a carbon coating on a ceramic element, with
the carbon cut into a spiral.
Metal oxides and metal films are the manufactured same way except the
film is metallic.
Cut one open and look at it.
73, Tom W8JI
w8ji.tom@MCIONE.com
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