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[AMPS] impedance of nichrome lower

To: <amps@contesting.com>
Subject: [AMPS] impedance of nichrome lower
From: measures@vc.net (Rich Measures)
Date: Thu, 11 Sep 97 12:15:10 -0800
>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.  
>
>Not true, as DejaNews would show, but I'll bite again.

In the 260 plus kilo-word archive, which I did not fully read, I found 
where I asked Messrs. Stewart, Rauch, Bertini and Coffman to design one, 
however I could not find an instance of my asking you.  If I never asked 
you to design one, sorry for the error, Ian.  
>
>The N7WS measured Rp and Lp values for Rich's suppressor at 100MHz are
>Rp = 103.2 ohms, Lp = 123.9nH. With ideal components, those are the  R
>and L values you'd connect in parallel to EXACTLY reproduce the
>behaviour of Rich's suppressor at 100MHz.

103 ohms is the parallel-equivalent R (Rp) of Ls & Rs at 100MHz.  What 
are the actual values of Rs and Ls?

A suppressor that clearly outperforms the Handy-Measures R-wire 
suppressor tested by Wes, looks like it could easily be designed using a 
copper-wire Ls.  For instance 200nH of Ls and 200 ohms of Rs would do it. 
...  However, there seems to be a sticky wicket.  The C-reactance of a 
3-500Z anode at. 29MHz is minus.1100 ohms.  With an anode RF potential of 
up to 2700V rms, we have 2700v/100-ohms = 2.4A rms of RF current through 
the suppressor.  
The power being dissipated in Rs at 29MHz is: _____________?
>
>But that simply begs two more questions:
>
>1. What about real-life components?
>2. What happens at other frequencies?

indeed, Ian - which is why I asked the question above.  Until we go 
through the necessary calculations to find P, commenting on the remainder 
of your reply needs to QRX.  
cheers
Rich---

R. L. Measures, 805-386-3734, AG6K   


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