[ARC5] Re: [Milsurplus] GF and RU Relationships

[Michael Tauson]

On Fri, Mar 21, 2008 at 7:22 PM,  <WA5CAB at cs.com> wrote:

> Second, aside from being made by WECo instead of ARC, the RU-18 and -19
> receivers are the same as later production RU-11 and -12.  RU-11 (S/N 1-300) and
> RU-12 (S/N 1-250) used 46048C.  Higher numbers and all RU-18 and -19 use 46048D.

In 1943, A.R.C, WE and the Navy had a sit down because there were
problems with some of WE's RU receivers.  Specifically, the coil sets
wouldn't interchange because they were off calibration much the same
as any other coil set put in those receivers was out of calibration.
Those receivers and coil sets would only work with themselves.

The source of the problem was that A.R.C. had specified a particular
brand of tube (Sylvania?) and WE used RCAs which, at the time, were
out of spec even though they got past internal and Navy inspectors.
The difference in inter-electrode capacitance was sufficient to affect
tracking.  WE's solution was to modify the coil sets so they would
track properly but that ruined them for use in any other set and, of
course, the tube capacitance put regular coils out of calibration.

WE agreed to change over to the correct tubes and indicate that the
modified equipment could only be used together, A.R.C. agreed they
should have been a lot more emphatic about the tube specification and
the reasons for it, and the Navy went to RCA to find out what their
story was.

I suspect that the RU-12 and RU-18/-19 are those receivers.

BEst regards,

Michael, WH7HG