[Heathkit] Heath SB-310 SW receiver differences in models

[Bruce Sugarberg]

Hello Ian,

Chuck Penson's "Heathkit - A Guide To Amateur Radio Products, 2nd Edition",
says:

SB-310 (Page 239)
-----------------
"An optional kit converted the 11 meter Citizens Band to 13 and 15 meter
shortwave coverage.  The conversion is easy to spot since it included a
new dial legend plate on the band switch".  No date is listed for this
change.  The production dates of the SB-310 were 1967-1972.

73, Bruce Sugarberg WA8TNC
==========================
Ian wrote:
> I am still "playing" with the SB-310 that I recently got.
>  
> The schematic that I found has the highest band being the 11 Meter CB
> beginning at 26.9 MHz up to 27.4 MHz.
>  
> The receiver I actually have does not cover that range and instead covers
> 21.3 MHz up to 21.8 MHz.
>  
> My receiver has a matching small plate covering the band switch area that is
> screened with the correct ranges.
>  
> My question is:
>  
> *  When and why did the coverage change from 26.9 to 21.3?
>      I assume that since there's the plate over the band switch area that
> this would be a later receiver...
>  
> Thanks,
>  
> Ian, K6SDE