[ARC5] Re: [Milsurplus] NEEDED: GP-7 Bits

[Mike Hanz]

David Stinson wrote:

>p.s. Mike H.: You once told me the scoop on that pointie thing
>on the antenna connector (which now has blood on it from my finger).
>But I've forgotten...
>

Ah yesss....the old Rajah spark plug wire connector ploy...  For some 
reason, the Navy chose to be different with the 1930s sets, seeming to 
opting for stranded wire rather than the solid tinned copper (and 
sometimes copperweld) preferred by the USAAC.  There are certain 
advantages to it, including the ability to throw together a nice patch 
panel for multiple antennas.  The photo of the PB4Y-2 at the bottom of 
http://aafradio.org/flightdeck/RAX-1.htm shows a pair of triangular 
pieces of plexiglas used in that way.  The disadvantage is the need to 
restrain it at more frequent intervals, and they seem to have shifted 
their philosophy later on to a more user friendly push-terminal like the 
rest of the world - possibly because of sailors reporting to sick bay 
with holes in their fingers from the pointy thing in the Rajah 
terminal.   :-)   With stranded wire, the secret is to spread the 
strands around the point and then screw on the cap until the wires are 
captured in the cone space between the cap and the needle.  Simple, 
huh?  If you are trying to use solid wire, you have to carefully bore a 
.0046" hole in the end, and then slit it four ways with a .002" slitting 
saw....oops, no, I forgot...can't use that explanation until April 
1st...heh.  Easiest way it to use a short (1") piece of stranded and 
solder it to the solid wire, but you can also make an adapter out of 
brass on the lathe to fit inside the cap.  Basically it looks sorta like 
a tiny top hat, with a hole through the center to solder the wire into 
one end and provide clearance for the needle point in the other.  That's 
the cleanest solution, and the one I used.  I suspect, but can't yet 
prove, that the Navy used a similar approach in the transition years of 
the war.  Otherwise we would have seen a rise in medical treatment for 
puncture wounds as more newbies came into the Fleet.

>p.p.s.  Was the GP-7 always paired with either the RU or 
>the RA-1?  Anyone heard of it being hooked-up with something
>like an RAX, maybe?
>

I have no doubt it was used at one time or another with most of the 
Fleet aircraft receivers, but the standard one seem to be the RU.  Only 
one case lists it with an RA-1B.  Not a bad transmitter (the tuning 
units are works of art internally) but the size forced the designers to 
use a tiny blower motor to cool the 803 PA, and that complicates things 
if you wish to use a frequency of other than 800 cycles as primary 
power.  You still have to figure out a way to bring fresh air into the 
cabinet to cool that PA.  It is doable, but not trivial.  Easier to just 
com up with an 800 cycle source, frankly.

73,
Mike