W7RY wrote:
> The very late SB-220s and HL-2200s had longer tune caps. Or Heathkit
> made them available on a replacement basis. I have seen several SB-220s
> with them.
>
"LOU" wrote:
> OF THE DOZENS I HAVE SEEN INCLUDING HL-2200'S THIS WAS NOT THE CASE
> ALTHOUGH I NEVER TOOK MEASUREMENTS MY FEELING IS THEY WERE ALL THE SAME.
>
In late 1987 or early 1988, after some months of frequent arcing at my
SB-220 plate tuning capacitor (stock P/N 26-131), I ordered a
replacement from Heath. In return I received P/N 26-164 and a service
bulletin page from Heath Zenith that stated, in part:
"A new tuning capacitor, Part # 26-164, is being supplied in place of
part #26-131 that you ordered. The new tuning capacitor is about 1-1/2"
longer than the older one, so it is necessary to install a spacer at
"DA" to permit proper mounting at the plate coil...."
I installed this capacitor on February 7, 1988.
A Google search on "Heath SB-220 26-164" (without the quotation marks)
led me to the following from a July 1997 posting by KM1H to the Amps
archives:
"9. Most SB-220's and early 221's will have the small Johnson 154-9 Tune
cap or the OEP 26-131. This cap is prone to arcing since it is only
.075"/3KV spacing. Later amps and Heath replacements were the OEP 26-164
which is about .090/3500V spacing. It will still arc on occasion when the
amp is mistuned but not melt down as did the original. There is no
Johnson/Cardwell equivalent. If there is enough interest I will have the
26-164 reproduced."
I hope the above is adequate documentation of the facts concerning the SB-220
Tune capacitor.
Bud, W2RU
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