[ARC5] GF/GF vs. RU-2/GF

[Mike Morrow]

Phil wrote:

>I used to have a copy of a Navy letter describing the results of testing
>the RU-2 receiver for acceptance into the GF units. I believe the date 
>of the letter was 1932. At this time the GF was both a transmitter and
>a recever. It looks like this was the time the orginal GF receiver was
>dropped and the RU was coupled to the GF units. I think the GF
>receiver did not have the telegraph osc.

Phil,

That letter, should you find it, would be most interesting to us old
radio history nuts.

This is a great point for discussion, which forced me to research that
alters my earlier understanding of early RU and GF relationships.
I had thought that the original GF receiver and the RU-2 were different
nomenclature for the same receiver.  Visually, they would look identical.
SHIPS 242A states that the RU-2 is the associated receiver for the GF
transmitter.  Information from a couple of web sites reveals that the
RU-2 receiver (with three RF stages, detector, heterodyne oscillator,
and audio amp) is considerably different electrically from the original
GF receiver (with four RF stages, detector, NO heterodyne oscillator,
and audio amp).  It wasn't just a nomenclature change for the original
receiver.

The original GF set (nomenclature applied to both transmitter and receiver)
can be seen in the two-page GF description in the late-1950s USN "Directory
of Communication Equipment", vol. 5, found on Nick England's amazing site: 

 http://www.navy-radio.com/manuals/94200/94200_1_09-2.pdf

The contract date for the GF system was 10 November 1932.  The GF receiver
is CBY-46006, supplied with coil sets for 224 to 350 kHz and 5400 to 8100
kHz.  It receives MCW only, and has no AGC.  The GF receiver is obviously
the parent to the RU-2 and later, but it is definitely NOT an RU-2.

Mike Hanz's also amazing site has excerpts from mid-1930s USN publications
that describe the RU-2A.  One such document is:

 http://aafradio.org/docs/1935-Navy-Radio-Gear.pdf

The 1937 RU-2A has a coil set only for the beacon band (200 to 400 kHz).
The original 1932 RU-2 has coil sets for 224 to 12500 kHz.  The RU-2/-2A
is the CBY-46012.  It receives MCW and CW, but has no AGC.

The descriptions on Mike's site also discuss the 1934 RU-3.  It has coil
sets for 224 to 13575 kHz.  The RU-3 is the CBY-46036.  It receives MCW
and CW, and has AGC.  The RU-3 established the pattern for all subsequent
RU receivers.

Here's a summary of information from Mike's (and other) documents:

Receiver                 Frequency (kHz)       CW    AGC   Date

CBY-46006, part of GF    224-350, 5400-8100    NO    NO    1932
CBY-46012, part of RU-2  224-12500             YES   NO    1932
CBY-46036, part of RU-3  224-13575             YES   YES   1934

It appears to me that early GF sets used the GF CBY-46006 receiver
which had NO CW reception facility.  Later GF sets used the RU-2
CBY-46012 receiver, which could receive CW.

So, perhaps this is the early GF sequence:

Receiver  Transmitter
GF        GF
RU-2      GF
RU-3      GF-1

Does anyone have a manual for the GF or the RU-2/GF and can verify
the use of the RU-2 CBY-46012 with the GF transmitter?  The earliest
manual that I have is for the RU-3/GF-1.  I suspect that if the RU-2
was used with the GF, a complete coil set wasn't carried along.

Mike / KK5F