[Hallicrafters] Hallicrafters receiver R -274 GI SX 73?

[Barry Hauser]

Greg wrote:
>Can someone give me some information on this receiver?  This seems to be
>a very rare Hallicrafters in that I have not seen or heard of  this one
beyond the picture in the
>Collector guide.
>Here's what I know so far: 
>Circa 1952
>Single and Dual conversion
>Turret band switch
>Rack mount
>I am buying one tomorrow from a local gentleman.
>Found two references: "Militarized SX 73"  and  "Similar to SP 600"
>Sure would like to hear from an experienced person on this one

Hi Greg and Gang:

I don't see any replies posted on this, so I'll take a shot at it.

Recently acquired one of these and I've been into the works in some
detail.  It carries the same primary nomenclature as the SP-600 which is
"R-274" as it is the functional equivalent of the Hammarlund SP-600.

In a nutshell, it's basically the same, only totally different. ;-) There
is a turret bandswitch arrangement as in the SP-600, but it has formed
bakelite modules rather than ceramic ones and very different style of
contacts.  The design is is similar in that it's single conversion below
7 MC (approx) and double above that.  The frequency ranges per each of
the six bands are similar, but not exactly.  The physical layout is very
different.  

Among other differences I discovered:  In the SP-600, there is a cam
operated switch on the turret housing that engages the second converter
setup.  The SX-73 uses a DPDT relay, the primary of which is powered when
the circuit is completed by jumpers on the set of turret modules adjacent
to the ones for the band that's engaged. 

Not sure how rare they are, but they certainly are much fewer in number
than the SP-600.  To learn more about the rig, I'm pretty sure there are
one or two manuals on the bama site you can download.

Barry

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