[Milsurplus] SPF Forest Service Radio

Mike Morrow kk5f at earthlink.net
Thu May 28 21:05:31 EDT 2009


Mike wrote of his new SPF:

> It is in exceptional condition, not having have seen any "ham" help".
> It is a nine tube unit using 1 volt tubes. The crystal in it now is
> on 3425 KHz. Should be easy to get it on 75.

That's interesting!  I thought the SPFs were VFO-controlled.  I have
an essentially complete SPF that I've pretty much ignored since I saw
that it had a crystal socket (I didn't even look at the frequency of
the crystal).  I figured that was evidence of it having been "ham-improved"
and I immediately lost interest.  I guess I'll have to re-think and
re-examine.

I wish I could find a manual, schematic, or some other technical
information.  The SPF looks like a pretty cool design for the mid-1930s.

Bruce/VE7MT posted a couple of weeks ago the URL of an interesting May 1937
document describing forest service communications of that era.  There is a
short discussion and several pictures of the SPF in that document, so the
SPF must have been out in 1936 or earlier:

http://ir.library.oregonstate.edu/jspui/bitstream/1957/10690/1/Jones_Forrest_W_1937.pdf
(Thanks, Bruce.)

The SPF seems like it would have been a far more effective field-use
set than the monstrosities like the SCR-178 that the US Army was using 
at the time.

Mike / KK5F


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