[Heathkit] Differences: SB-220 vs SB-221

[Carl]

Wider space Tune cap which was also in the very late 220 and used as a 
replacement.

115pf grid caps

Plug in power transformer

10M with upgrade kit and proof of license. I built many with 10M while 
working at home for 2 local Heathkit stores.

R-4 and R-5 different

20, 80 input coils and matching caps for better VSWR

Under certain tuning conditions there can be switch arcing in the 220. Its 
easily mitigated by adding a 10-12pf 1000V or higher mica (or 6KV NPO disc) 
cap directly across the 20-40M switch contacts. Mouser carries a 10pf disc.

Carl
KM1H


----- Original Message ----- 
From: "Rick Poole" <wa1rkt at arrl.net>
To: <heathkit at mailman.qth.net>
Sent: Tuesday, March 27, 2012 1:03 PM
Subject: [Heathkit] Differences: SB-220 vs SB-221


>
> Other than 10 meters (present on SB-220, absent on SB-221), what are
> the differences between the two?
>
> I think I read somewhere that the -221 has a wider-spaced tuning
> capacitor (less arcing) but now I can't find that.
>
> (Is arcing really a common problem on the -220?)
>
> Thanks...
>
> Rick WA1RKT
>
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