[Amps] Nichrome wire for suppressors

[Carl]

Globars werent available in RETMA steps to R&D and having custom ones 
made may or may not have improved anything.

Ive no argument with the rest of your reply.

Carl
KM1H


----- Original Message ----- 
From: "Joe Subich, W4TV" <lists at subich.com>
To: "'Carl'" <km1h at jeremy.mv.com>
Cc: <Amps at contesting.com>
Sent: Wednesday, February 11, 2009 11:03 AM
Subject: RE: [Amps] Nichrome wire for suppressors


>
>> I personally saw the results, as strictly an observer, of a 3CV1000
>> military amp prototype that defied all attempts to stabilize until a
>> 1/2" wide ribbon of Mumetal was wound around the big Globar. It then
>> passed all tests 2-30 mHz using a reactive dummy load to
>> simulate VSWR's of up to 4.5:1 of either sign.
>
> I don't think that anyone is arguing that resistive loading isn't
> a valid and useful approach to dealing with parasitics.  Commercial
> amplifiers of all kinds have used that approach, including nichrome,
> when the use of bulk resistances does not work (e.g., excessive
> resistance in the B+ line, insufficient space, excess reactance,
> etc.).
>
> However, Measures' claims are simply at variance with physics.
> Due to skin effects, the resistivity of nichrome has only minor
> effect on the behavior of the suppressor at VHF frequencies - it
> simply adds proportionally more resistance to the parasitic
> suppressor at HF, MF and LF frequencies.  Unless the tubes in
> question are unstable in or below the operating range, this
> added resistance is of no value and the same effect can be
> obtained by adjusting the value of the fixed resistor in the
> suppressor.
>
> 73,
>
>   ... Joe, W4TV
>
>
>
>
>> -----Original Message-----
>> From: amps-bounces at contesting.com
>> [mailto:amps-bounces at contesting.com] On Behalf Of Carl
>> Sent: Wednesday, February 11, 2009 10:22 AM
>> To: Vic K2VCO; Gudguyham at aol.com
>> Cc: Amps at contesting.com; Gary at doctorgary.net
>> Subject: Re: [Amps] Nichrome wire for suppressors
>>
>>
>> And here is a third comment on the subject.
>>
>> BOTH are partially wrong, Measures for his ideas about
>> parasitics being
>> the cause of everything bad that happens.
>>
>> Long before W8JI came along and declared himself the messiah of all
>> things some commercial and military amps used nichrome or
>> mumetal as the
>> suppressor inductance. If you go back to the 90's archives I
>> mentioned
>> it a few times and then gave up as a few people will not
>> accept anyones
>> ideas but their own.
>>
>> I personally saw the results, as strictly an observer, of a 3CV1000
>> military amp prototype that defied all attempts to stabilize until a
>> 1/2" wide ribbon of Mumetal was wound around the big Globar. It then
>> passed all tests 2-30 mHz using a reactive dummy load to
>> simulate VSWR's
>> of up to 4.5:1 of either sign.
>>
>> So, before anyone goes off half cocked and believing everything they
>> read on the Internet please consider the above.
>>
>> Carl
>> KM1H
>>
>>
>>
>>
>>
>>
>>
>>
>> ----- Original Message ----- 
>> From: "Vic K2VCO" <vic at rakefet.com>
>> To: <Gudguyham at aol.com>
>> Cc: <Amps at contesting.com>; <Gary at doctorgary.net>
>> Sent: Tuesday, February 10, 2009 11:15 PM
>> Subject: Re: [Amps] Nichrome wire for suppressors
>>
>>
>> > Gudguyham at aol.com wrote:
>> >>
>> >> In a message dated 2/10/2009 10:36:09 P.M. Eastern Standard Time,
>> >> Gary at doctorgary.net writes:
>> >>
>> >> Anyone  have a suggestion where I can find quick & easy
>> find about a
>> >> foot of  nichrome wire to be used in parasitic suppre
>> >>
>> >>
>> >> Does anyone dare answer this?
>> >
>> > Sure. The use of nichrome wire in VHF parasitic suppressors is
>> > controversial. A very good
>> > explanation of VHF stability in vacuum tube amplifiers which argues
>> > *against* the use of
>> > nichrome wire can be found at <http://w8ji.com/vhf_stability.htm>.
>> >
>> > If you want to see the opposite side, look at Rich measures' site,
>> > <http://www.somis.org/>. He also will sell you a kit including wire
>> > and the appropriate solder and flux to make a nichrome suppressor.
>> >
>> > Personally, I think that although many of Measures' ideas are
>> > useful -- I like his fast
>> > t/r switching circuit -- he is wrong about the nichrome and W8JI is
>> > right.
>> >
>> > That wasn't bad, was it?
>> > --
>> > 73,
>> > Vic, K2VCO
>> > Fresno CA
>> > http://www.qsl.net/k2vco
>> > _______________________________________________
>> > Amps mailing list
>> > Amps at contesting.com
>> > http://lists.contesting.com/mailman/listinfo/amps
>>
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>
>