Collins C-975/URR Description

Gibbs, Dennis dgibbs at RATIONAL.COM
Sat Jan 30 12:54:14 EST 1999

Hello Jan and the group:

Jan Skirrow wrote:

> Hi folks ...
> Someone has asked me if I know anything about this unit. The only info
> found so far is that it is a receiver control that operates in conjunction
> with two R-390s to make up the AN/FRR-39 set. Can anyone provide more
> Any ideas what it might be worth?
> Jan Skirrow, VE7DJX
> Duncan, BC, Canada

I have one of these units, along with the manual.  I thought I would post a
description of this unit for those that are interested.  Here's an excerpt
from the manual:

Receiver Control C-975/URR is designed to provide automatic frequency
control (afc)
of the audio frequencies used in a radioteletype system when the frequency
shift is
850 cycles per second (cps).  The equipment normally operates in
conjunction  with
two Radio Receivers R-390/URR or R-391/URR.  Separate control  channels
within the
receiver control are used for the two receivers, but the power supply and
circuits  are  common.  The receiver  control  corrects for  both
transmitter  and
receiver drift and reduces retuning requirements.

The receiver control operates with an input frequency of 455 kilocycles
(kc).  The
455-kc intermediate-frequency  (if.)  signal  from  each  receiver  is
applied  to
separate input circuits.  Each if. signal is mixed  with  the  output  of  a
frequency oscillator (bfo) and the resulting signal of  2,125  and  2,975
cps  are
available at the output terminals.  The afc circuits function to maintain
the 2,125
cps mark signal on frequency, thus correcting for frequency  drift  in
either  the
transmitter or the receiver.

The receiver control is intended for use in a fixed  station  and  not  for
operation.  The equipment can only be used as  part  of  a  system, such  as
Receiving Set AN/FRR-33 or AN/FRR-39.  These radio receiving sets are
intended  for
operation with Radioteletype Terminal Equipment AN/FGC-1.

End of excerpt from manual.

This unit weighs about 50 pounds and is slightly smaller (8.75 inches vs.
10.5 inches)
than the R390 receiver family.  It has 35 tubes in it, with a tube
complement of:

2D21W           2
3A4             1
6BH6            9
6BJ6            6
6C4             2
6J4             1
12AU7           7
26Z5W           2
5651            2
5654/6AK5W      2
6082            1

My unit was purchased from a person who claims they uncrated it from the
packing material, and I believe it - The unit is in beautiful condition.
Mine was
manufactured by Collins, on contract 26566-PH-52-51.  The manual is dated 31

I do not know how much these are worth, but this is the only one I've ever
seen and
is certainly immaculate.   If anyone wants more information about this unit,
let me
know.  Hope this was informative!

Dennis Gibbs
dgibbs at

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