[AMRadio] SB-221 to SB-220 Conversion

[LEE BAHR]

Can the conversion of a SB-221 be made to a SB-220 from readably available 
parts?  I am in the market for an amp for my club W5DRC.  I was and still 
might be looking for a SB-200 that looks clean in which I could install the 
Harbach updates and wind up with a nice amp.  We want 10 meters on the amp. 
That was our initial plan.  However, a friend of mine just contacted me and 
said he has a nice SB-221 he would sell me.  But, the amp doesn't have 10 
meters on it.

I think, to make the conversion I would need an input coil, a changed out 
input wafer switch and a tank coil wafer switch and then tap the 20/15 meter 
coil .  I can't find anything on the internet how it actually would be done 
or if it can easily be done.  I don't find anything in the FILE section 
either of this group.  If I can't fairly easily put 10 meters on the SB-221, 
I need to tell my friend I am going to pass and look for another amp.  I see 
Harbach sells a wafer that would work for adding 10 meters to the tank 
circuit.  I would think the input coil would not be too hard to duplicate, 
but the input wafer may be hard to find or very costly making the conversion 
not worth while.

Does anyone on here know what can be done and procurred for the conversion? 
Frankly, I was suprised to not be able to find anything about doing this on 
the internet.  I do realize Heath once had a conversion kit available, but 
my chances of finding one of those would be slim to zero these days.

One last thing, are the Chinese 572B tubes sold with the Taylor name on them 
from RF Parts any good these days?  Those tubes scare me if we wind up with 
a SB-200.  (I know a couple years ago the Chinese 572Bs were bad news and 
the Svetlana tubes were really made for audio and had smaller plates on them 
so they were not really good either.  Plus the fact the 572Bs in a Heath amp 
lie on their side causing "sag" with some of the Chinese tubes).

Can anyone help me out regarding all this?  Thanks for the consideration.

Lee, w0vt