The role of a suppressor is to stop a parasitic from starting in the first
place. If it absorbs power it is not designed properly or is simply a brute
force method using a sufficiently high wattage resistor.
Carl
KM1H
------ Original Message -----
From: "Alex Eban" <alexeban@gmail.com>
To: "'Steve Thompson'" <g8gsq@f2s.com>; <amps@contesting.com>
Sent: Tuesday, July 27, 2010 4:19 AM
Subject: Re: [Amps] More parasitic choke questions
> None of these apply!
> All these resistors are meant to do is lower the Q of the suppressor
> inductance and dissipate the harmonic energy involved. Their stability is
> of
> no concern, since the circuit is not so critical as some believe.
> On the other hand, composition resistors have the lowest parasitic
> inductance of the generally available resistors and this is definitely an
> important characteristic, since this inductance can easily hamper proper
> suppressor operation.
> BTW, your inductance measurement is off: a piece of wire one inch long is
> approximately 25-30 nH, not 2-3nH. You have to add it to the resistor's
> inductance. You simply can't connect it with zero length wire!
> Alex 4Z5KS
>
> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
> Behalf Of Steve Thompson
> Sent: Tuesday, July 27, 2010 8:36 AM
> To: amps@contesting.com
> Subject: Re: [Amps] More parasitic choke questions
>
>> It does seem though as
>> if the preferred carbon composition resistors are no longer easily found.
>
> What is preferred about carbon comp? Given the heat and the need
> for long term stability in value they're the least suitable
> component you could choose.
>
> Some years ago I measured some different suppressors(results in a
> posting on 30 Aug 06), subsequently I swapped the carbon comp
> resistors for MOX on a couple of them, and couldn't measure the
> difference. Whenever I measure 2 or 3W MOX resistors in the 20-100
> ohms range, the inductance is in the regions of 2-3nH, which has
> minimal impact in a suppressor. Inductance is higher in the 5W
> ones I've tried.
>
> Steve
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