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Re: [Amps] sb-220 tuning question - closing in

To: "Pete Smith" <>, <>,"Dan Sawyer" <>
Subject: Re: [Amps] sb-220 tuning question - closing in
From: R.Measures <>
Date: Fri, 5 Mar 2004 00:14:16 -0800
List-post: <>

>Isn't this all getting a little over-complicated?  If both tune and load 
>controls are adjusted for maximum output at rated drive (~100 watts),

**  It takes c. 140w to drive a pair of 3-500Zs operating at 2800vdc.

> there should be no arcing and performance should be nominal.  

**  A pair of 3-500Zs has 0.3pF of feedback C.  So, at 110MHz, XC is c. 
5000-ohms between the output and the input of the tubes.  If one ignores 
this feedback path, there should be absolutely, positively no 
intermittent parasitic arcing.  

>If you want, add a 
>little loading (clockwise) past peak output for better IMD 
>performance.  Once you're peaked, tape an index card behind the knobs and 
>mark the settings for each band.  

**  I use different colored Crayola's to show the settings for different 


cheers, Pete
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