SB-220/SB-221 Differences

[Bob And Bettina Groh]

I was the one who did the engineering on the modification (for both the
200 and 220) but darned if I can remember all the details (old age and
too many years ago).  I do know I eliminated the 10M band position (i.e.
went to a 4-pole bandswitch) and (I think) put a LPF in the input (about
a 24 MHz cutoff).  I do remember having to modify the input network a
bit to accomodate the impedance changes due to the LPF. In hindsight, I
went overboard and we (Heathkit) should have just put a mechanical stop
on the bandswitch and deleted the input network on 10M.  Probably would
have made the FCC happy.  I suspect some of the other old timers from
Heathkit on the list could provide a little bit more explicit record of
the changes.  In fact, it might be a good idea to do it for posterity sake.

73
Bob Groh, WA2CKY
'Heathkit Engineer from 1977 to 1981'

GALE STEWARD wrote:

>My brother-in-law recently purchased an SB-221 and I
>have had an SB-220 for years. He got to wondering that
>differences there were between the two. As I recall,
>the SB-221 came without 10M in the original kit. You
>could then get the additional parts kit to put it on
>10M with proof of a valid amateur license. I may have
>this wrong or there may be other differences that I
>was never aware of. Any info appreciated!
>
>73, Stew K3ND
>
>
>
>
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