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[AMPS] FAILURE OF PARASITIC RESISTORS IN AL-811X AMPLIFIER

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Subject: [AMPS] FAILURE OF PARASITIC RESISTORS IN AL-811X AMPLIFIER
From: N5JA@contesting.com (Jon A. Barclay N5JA)
Date: Wed, 01 Mar 2000 13:17:54 -0600
measures wrote:
>
> A 100-ohm, 3w Matsushita MOF resistor has c. 11nH...

A while back I did some tests with my MFJ-259 and some of the 5-watt
metal-oxide resistors from Mouser, and posted my results here on AMPS.
I estimated their inductance by resonating several little capacitors
and sweeping the MFJ-259 to find the resonant frequencies.

Rich was good enough to send me a few of the 3-watt Matsushita MOF
resistors that he uses.  By the time I'd tried to duplicate my
experiment with these, the subject was ancient history on the list.
I decided I'd wait until the subject came up again...

Anyway, for anyone interested, the 3-watt Matsushita resistors were
considerably less inductive than the bigger 5-watt resistors I'd
tested before, enough so that my crude test mechanism was inadequate
to even get ballpark numbers.

It was interesting to note, however, that different values of
resistance had considerably different values of inductance.
Inspection of the resistors with the outer coating removed showed that
some values of resistance were significantly more "spiraled" than
others;  of course, the ones with the least spiraling had the least
inductance.

73,
Jon, N5JA
--
Jon A. Barclay
N5JA@contesting.com
jbarclay@vulcraft-tx.com

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