[AMPS] impedance of nichrome lower

km1h @ juno.com km1h@juno.com
Thu, 11 Sep 1997 17:11:06 EDT


On Thu, 11 Sep 1997 13:28:56 +0000 w8jitom@postoffice.worldnet.att.net
writes:
>> From:          "Ian White, G3SEK" <G3SEK@ifwtech.demon.co.uk>
>> Subject:       Re: [AMPS] impedance of nichrome lower
>> Date:          Thu, 11 Sep 97 07:46:57 +0000
>
>Hi Ian,
>
>I thought about just ignoring Rich's comments, because this stuff 
>just goes on endlessly. 

The rest SNIPPED

It could stop if there was agreement Tom. The way I view it is that there
are a number of individuals on this reflector with engineering
backrounds. I have yet to see a unaminous  consensus on the suppressor
issue. To me that means a lot more discussion is warranted, no matter how
painful to some.

I have no personal interest in who wins; I just want to know the answers.


Remember, they used to execute those who professed the world was not
flat. 

73...Carl  KM1H


But in fairness I guess I should correct one 
>thing he said.
>
>> Rich Measures wrote:
>> >During the grate suppressor debate, I repeated asked Mr. Rauch to 
>design 
>> >a copper-wire parasitic suppressor that equaled the performance of 
>the 
>> >resistance-wire suppressor.  I repeatedly asked Ian White and Wes 
>to 
>> >design one.  ......... So far, nothing.  
>
>Ian said:  
>> Not true, as DejaNews would show, but I'll bite again.
>
>Not true as Dejanews says, and not as I recall either. The same is 
>also so with Rich's references to my making comments about 
>Rich's nurse. As a matter of fact, just two days ago right here Rich 
>blamed that one on N7WS. Today he blames it on me.
>
>The truth about that, as I recall, was that Rich asked Wes to NOT 
>post the test results because it would mean laying off his nurse, 
>who helps ship the kits Rich sells. Rich said his nurse needed the 
>money. To which Wes replied he didn't care if Rich's nurse got 
>to lick stamps or whatever he does for a living. Why I'm any part of 
>that conversation, or what on earth such a simple comment means, and 
>what it has to do with the topic at hand.... is beyond me. I 
>certainly had nothing to do with that verbal exchange.
>
>> The second question is: what is the difference between the two types 
>of
>> suppressor at other frequencies?
>> Plotting the N7WS measurements on a (log Q) versus frequency scale
>> showed that the Q values of the two different types of suppressor 
>track
>> quite closely across the VHF range. The measured Q values were about 
>40%
>> different at 100MHz, but the two curves run pretty much parallel 
>across
>> the VHF range. On a log scale, that means that they pretty much
>> maintained a 40% ratio between them.
>> 
>> So, if you make a conventional R/L suppressor that mimics the Rp-Lp
>> behaviour of the R/NiCr suppressor EXACTLY at one chosen VHF 
>frequency,
>> you'd then find that the two curves remain very, very close across 
>the
>> VHF band.
>> 
>> But N7WS's measurements show that the Q of the conventional 
>suppressor
>> rises FASTER at HF - in other words, at HF it looks less like a 
>resistor
>> and more like a small inductor, which is exactly what it's supposed 
>to
>> do. The Q of the R/NiCr suppressor also rises at lower frequencies, 
>but
>> more slowly. In other words, the significant difference between the 
>two
>> types of suppressor is not at VHF, where their performance can be 
>made
>> almost identical. The main difference is at HF.
>> 
>> OK, that's it for a second time, in a different newsgroup and 
>hopefully
>> explained even more clearly.
>
>The best use would be in a system with HF or near HF instability, 
>although a low-Q tank would do the same thing.   
>
>73, Tom W8JI
>
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