[Milsurplus] Curiousity...

[antqradio@juno.com]

Greetings to the List
Interesting thread.  I agree with Al in that the SRR-FRR receivers use
the older technology with a variable first LO while the R-390 uses
crystal controlled.  Is drift a problem?  Not for band cruising, but for
fleet crypto messages which require high stability, yes.  I enjoy the set
because of the projection dial, the big meatball logo AND the solder in
tubes.  When I last used it, I didn't notice any problems with drift. 
After warm-up, I dialed in WWV with the very narrow CW filter and didn't
notice any stability problems, but then again, I got bored with the
filter ringing and after a few minutes started cruising the short wave
bands.  As an aside, is the SRR series the first military radio receiver
with mechanical filters?

Soldered in tubes in the SRR series receivers are no more a problem then
in the KWT-6 or the 50E-8, which are higher stability synthesized sets
also of Collins implementation, similar to the ARC-58.  These are hybrids
with a mix of tubes and transistors.  Some of the tubes are 7 and 9 pin
plug in while others are soldered in subminiature.  Reliability was high
in an conditioned trailer.  The two years that I maintained these sets in
the Air Force, my only recollections on problems was a sleepy operator
setting the wrong console switch at 3 AM.  So with the KWT-6, drift and
accuracy was maybe 2 cycles while the R-390 was 100 cycles or so.  The
SRR series receivers may be twice (or three times) the R-390's drift, but
it is easier to tune.

If you want to set a frequency and not worry about drift, get a R-1051. 
Beats both the SRR and R-390 for stability, weighs about the same (100
pound class) but is even more difficult to cruise the bands.

Regards from Arkansas,
Jim


On Fri, 28 Jun 2002 08:52:38 -0400 Al Klase <skywaves@bw.webex.net>
writes:
> "Kenneth G. Gordon" wrote:
> > 
> > Can anyone in the group explain why the SRR-11/12/13 and the
> > FRR equivalents were never used as much when compared with
> > the R389/390 series?
> > 
> 
> The big difference is architecture.  
> 
> The SSR-13, introduced in 1950, was double conversion with
> 1600/200KHz IF's.
 -snip - 
Add to that, soldered in sub-minature tubes, some of which were running
too hot, and
> you're probably going to be interested in a better set.
> 
> The R-390, 1951, based on the slightly earlier 51J, uses
> triple conversion with a crystal-controlled first local oscillator.  
-snip-.
> The Collins receivers represent a major shift in
> general-coverage receiver design, and were fundamentally
> superior to everything that came before in frequency
> accuracy and stability.
> 
> If you want to find them, use a Collins.  If you want to
> listen to them, use a Hammarlund.
> 
> 73,
> Al