[Hallicrafters] sx-73 (r-274)

[Bob Krassa]

At Jack's suggestion, following my request for a copy of 
change 1 to TM 11-897, I contacted John K4OZY and he scanned 
and added it to his excellent website 
http://jptronics.org/radios/Hallicrafters/manuals.html.  My 
interest was to establish what are the differences between 
the R-274 and the R-274D.  I had thought the placement of  
bathtub caps C198 and C199 on a vertical plate between T30 
and T31 and forward of V11 (straight back from the meter) - 
was the most obvious sign of the D model and that in the non-
D version, they are simply on top of one another.  Now, this 
is not mentioned in Change 1 to the TM and I am wondering if 
this change was made during production of the D version.  In 
that case, early D production would have the same 
arrangement of C198 and C199 as the non-D.  According to 
Change 1 the differences are that the band numbering uses 
arabic 1 through 6 instead of Roman I through VI, there is 
an antenna disabling relay K-2 under the chassis in the back 
(plus an neon lamp across its contacts on later serial 
numbers), and the lettering on the rear panel is revised.
73, Bob Krassa KC0TDS