[Hammarlund] Hammarlund SP-600 History Item

[Todd, KA1KAQ]

On Sun, Sep 7, 2014 at 6:37 PM, James A. (Andy) Moorer <
jamminpower at earthlink.net> wrote:

> I don't know, but here's what I would guess:
> Their competition was the RBB, the AR-88, and the SX-28. All
> single-conversion. The SP-400 was quite a good seller to the military (as
> the BC-779). I would not be surprised if there wasn't a big Signal Corps
> contract that came up and they needed a competitive advantage. The SP-600
> looked and behaved a lot like the BC-779, but it was (is)
> double-conversion. It was probably the cheapest, easiest hack they could
> come up with to make a double-conversion receiver to give them a
> significant competitive advantage. The imaging in single-conversion
> receivers had been a continual drumbeat for a couple of decades, made worse
> by the development of transmitting tubes that could actually hit that high
> range (above maybe 20 MHz).


Aside from some similarity in layout, I don't find a lot of resemblance
between the -600 and -200 series which the military bought in large numbers
for WWII. The SP-600 was actually spec'd as the R-274 along with the
Hallicrafters SX-73. Both are excellent receivers for their original
purpose. The fact that there were so many different version upgrades and
numerous other agencies bought the SP-600, combined with the fact that they
were around for so many years (commercial users like ITT were still using
them into the 80s) speaks volumes. Far from a quick hack, they were a well
built, purposeful design.

As to why the gov't bought so many SP-200s and later variants, it's simple:
they were available, tried and tested. SP-200s had been in commercial as
well as civilian service for several years before WWII broke out. More or
less in need of a lot of comms gear fast, Uncle Sam grabbed them up then
worried about the contract specs for later purchases. Other civilain sets
like HROs, SX-28s among others were procured. AR-88s had already been going
to the Commonwealth countries, England was also quite fond of the HRO and
S-27 VHF set.


> Now why they went to the turret assembly, rather than the switched
> arrangement of the above-mention receivers I will never know.
>

Halli used the same approach. A look at the original contract might reveal
the answer.

The fact that there are still so many SP-600s around says a lot about its
utility. While we may find shortcomings and nuisance issues today, mainly
with old components, they seem to have worked quite well for others for
many, many years.

~ Todd/KAQ