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Re: [Amps] SB220 "A" mods

Subject: Re: [Amps] SB220 "A" mods
From: Lee Buller <>
Date: Fri, 28 Mar 2008 06:10:58 -0700 (PDT)
List-post: <">>

You might look at the following after understanding the amp fully.......

Removing the grounded grid circuitry and just grounding the grids.  After all, 
it is a grounded grid amp.

Re-engineer the bias circuit for today's rigs and get rid of the 130 volts.  
(It was good  with the old SB line and others, but I would like something with 
a lower voltage DC switch)  I did not get to that before I sold mine off.

Learn how to load it properly so you do not get arcing in the Pi-Net circuit.

Editorial Comments:  
The SB220 is a great amp and quite stable as everyone has stated.  The 3-500Zs 
last a long time because you are not hitting them hard.  Life oft he tunes in 
the 220 should be 10 years or more unless you mis-used the amp.

I've always felt the 220 could use better shielding or something.  Mine was 
always a TVI generator for some reason.  I don't know if it was something I was 
doing wrong....bad TVs in the area....but it would generate a lot of TVI.  My 
Ameritron doesn't seem to do that.

Otherwise, the SB-220 can be very good amp if treated right.  The engineers at  
Heathkit did some remarkable things with that amp that made it affordable to 

Lee - K0WA

In our day and age it seems that Common Sense is in short supply.  If you don't 
have any Common Sense - get some Common Sense and use it.  If you can't find 
any Common Sense, ask for help from somebody who has some Common Sense.  Is 
Common Sense divine?
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