[Amps] sb-220 tuning question - closing in

[R.Measures]

>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 
bands.

>...

cheers, Pete