Heathkit SB-221


Dave Plowman:
What is the difference between the SB-220 and the SB-221 amps.
I think the 221 was a later version of the 220 and also think that the 221 was 80 - 15 only and the 220 was 80-10.
Is this correct or not.
Was one amp better in any way than the other?
I understand that there is an empty position on the band switch on the 221. Is that for a 10 meter mod that can be done and if so how difficult is it to do it.
I have a chance to purchase a SB-221 and don't want to make a mistake.
Any help would be greatly appreciated.
Dave W4PBU

Allen C. Ward:
The SB-220 and SB-221 are almost identical EXCEPT that the SB-221 will not operate on 10 meters (or CB). The components for 10 meters are missing and a filter is installed to prevent operation above 15 meters (I am not sure what the cutoff frequencies of this filter are). When Heath was in business you could buy the needed parts (switch wafer, 10 meter output coil, input filter etc.) for around $35. See the product review for the SB-221 on the ARRL web site. The modification was not all that easy. Today your best bet to get the needed parts would be to buy a junker SB-220 and remove the needed parts.
If you are interested in using the amp for 10 meters, I would suggest looking for an SB-220 (or SB-1000).
If 10 meter operation isn't needed the SB-221 will do fine for 80 thru 15 meters.
Good Luck Allen

Alan is right you will need a new band switch that has 5 positions. a tunded input circut. and have to tap the coil. you could remove these from a sb-220 amp and make them sork. but if your going to that trouble. i suggest just fixing up a sb-220 instead.

harbach electronics sells all sorts of stuff to make the ole sb-220 run like new agian.

Bill Jones:
I built my SB-221 as a kit and installed the 10 mtr. when I built it. In the "kit" of parts you bought from Heathkit for the 10 mtr. install was an instruction book for the SB-220. The only circuit difference I found on mine when I built it was the 221 had 3 33ohm resistors in series and the 220 had 2 50 ohmers (or vice versa). So I guess your answer is they are the same less the 10 mtr. tap.

Bill, W7ET

Wilburn T (Bill) English Jr:
Many of the SB221's are already modded for 10 meters, if you have a non marked bandswitch position to the right of 15 meters it's already been modded. Heath sold a 10 meter kit for the SB221 for about 40 bucks, and many people installed that on the initial build.

One thing is for sure, 220 or 221 they are hard to beat.

I have had my current SB-220 for over 2 years, I re-tubed it when I purchased it, but the original 35 year old Eimac's I pulled out where still making a KW. If the Eimac's I installed live as long as those did, it will outlive me! You just can't beat the 220, only downside is no 160, but there is a mod to add that if you gotta have it.


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