[Amps] SB220 "A" mods

[Lee Buller]

And......

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 hams.

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?