[ARC5] GF-12/RU-17 two-pin connectors and Test Meter

[Mike Hanz]

On 9/2/2011 6:43 AM, Andy Young wrote:
> Can anyone suggest a source of the little two-pin plugs used on the cable between the Junction Box and Antenna Relay Unit and on the Test Meter of the GF-12/RU-17 system, please?

Robert Downs has a few left, apparently.  They can be fabricated, if one 
has a drill press and a small lathe to use.  The knurled thumb nut is 
actually almost the same as used on the RU and SCR-183/283 tuning 
"speedometer" cables, so if you have any of those, that would save 
fabrication time.  A washer would have to be installed between the 
inside of such nuts and the connector body because the 'through' hole is 
larger than the one on the PL-77.  For the gluttons for punishment who 
might want to take a shot at making one, I have some dimensions and 
other thoughts at http://aafradio.org/garajmahal/PL-77.html - I had to 
go through the process in order to make a unique PL-76 that is identical 
except it has a single pin.  (Yes, it has no relationship to the *later* 
PL-76...the Signal Corps evidently had no compunctions about using the 
same number over for a "normal" banana pin  connector.)

> Speaking of the Test Meter, how was it used in practice? Did any installations include this meter as a permanent feature? It's not really a portable unit, it's meant to be mounted somewhere, so for ground set-up or repair on the bench a workshop test-meter would seem a better option.

The only installations where I have seen photographs of them permanently 
mounted have been in the test bench area.  I don't recall seeing them in 
any actual aircraft photos, but I never say never.  As KK5F mentioned, 
the manual mutters vaguely about the possibility of using it for DF 
readings, but the example cockpit photos I have here from the 
Smithsonian's collection (including the OS-8 Kingfisher at the bottom of 
http://aafradio.org/flightdeck/Peripherals-mikes.html ) doesn't have it 
anywhere in view.  It occurs to me that perhaps an audible DF, 
especially in the normal minima perception used most often, might have 
been "good 'nuff" for most applications.  Has anyone else seen any 
documentary evidence other than the RU/GF manuals?  The DU-2 manual here 
doesn't mention anything other than using an "output voltmeter" with a 
1.5v or 6v scale for cardioid maxima finding in the unusual condition of 
being very close to the bearing source (as if every navigator carries an 
output voltmeter in his pocket for such emergencies...) :-)   That sorta 
tells me that the use of the RU/GF test meter as a permanent fixture in 
most cockpits wasn't exactly widespread.

73,
Mike  KC4TOS