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[AMPS] SB-200 Parasitic Suppressors

To: <amps@contesting.com>
Subject: [AMPS] SB-200 Parasitic Suppressors
From: 2@vc.net (2)
Date: Fri, 26 Oct 2001 04:16:22 -0700
>
>Does anyone know what the spes are for the
>wire used with the SB-200 Parasitic Suppressors?
>Type, diameter, and how many turns required
>on the 47 ohm Carbon Composition Resistors!
>I broke one and need to make repairs.
>
The SB-200 was not unconditionslly VHF-stable with the original VHF 
suppressors.  The most common damage from this problem was arcing the 
open contacts on the 80m Tune-C padder switch - which switches in the 
100pF padder on the 80m band.  Oscillation is especially a problem with 
newer production 572Bs because they exhibit more VHF gain than the tubes 
originally used.  Thus, it might be a good idea to improve the suppressor 
by decreasing its VHF Q and Rp in order to decrease VHF amplification.  
This means using more Lsupp and more Rsupp.  Using resistance-wire 
instead of copper-wire also helps to decrease VHF Q.  The trade-off is 
that resistance-wire requires an acid flux and Silver-Tin solder to make 
satisfactorily connections.  
-  Murphy was right:  "Nothing is as easy at looks."  
>
cheers, Vince

-  R. L. Measures, 805.386.3734,AG6K, www.vcnet.com/measures.  
end


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