On Thu, 28 May 1998 09:17:03 +0000 Tom Rauch
<10eesfams2mi@mass1-pop.pmm.mci.net> writes:
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.
Well we disagree again....no suprise.
I would be interested in what L value you found in the 5W versions? I
can not even see any indication here on the old Tek 130. However the 3W
versions are very inductive.
As far as brand, I talked to a Mouser Product Mgr today and was assured
that a particular catalog part # was directly connected to a particular
manufacturer. If they changed sources the part # would change. The 5W
that I buy are made by Xicon and the mgr said that if Xicon sources from
different countries the specs are identical....I discussed inductance at
length and he was quite knowledgable about RF...a pleasant suprise.
So...dunno where or when you did your tests or got your information
but..........
Anyway they seem to work for me and the many customers that I have built
suppressors for.
>
>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.
At least one distributor is selling 2W as I described as composition
types. You should see what a 3-500Z does to them on 6M ! It was then
that I decided to investigate metal oxide and have been very happy with
the 5W Xicons.
73 Carl KM1H
>
>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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>
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