[Milsurplus] GRC-9 Drive Problem

[W7QHO at aol.com]

Richard et al,   

Recently ran into a leaky C114 here. Went back to your excellent article in 
ER #108 and restudied, with some dismay, your description of just how hard it 
is to get at this beastie.    After some thought, came up with the workaround 
described below.   Essentially what I did was ground the cold end of the 
doubler tank circuits and shunt fed the grid of the PA. Worked FB.

By removing the variable cap assembly I found I could reach the point where 
the lead coming out of the can from Point 3 on the circuit diagram connects to 
the wiper on "S101H Sect 4 FR".  There are two blue wires coming off this 
point too, one running over to pin 5 on the metering socket and the other to 
R106.  I first cut the two blue wires loose and then GROUNDED the lead coming out 
of the can from Point 3 where it connects to switch wiper, see above.  In 
cutting the blue wires snip off so as to give yourself as much lead length coming 
out of the cable they run into as possible, see below.

Next, remove the short black wire running from pin 3 (grid) on the 2E22 
socket over to the adjacent switch section and replace this connection with a .001 
mica.  Connect the two blue wires (see above) through a small RF choke to pin 
3 on the 2E22.  Bypass the cold end of the choke (where the blue wires are 
connected) through a .01 cap to ground.  Rather than leaving this end of the 
choke dangling I anchored the wire lead through a small hole drilled through one 
side of the fiber core of adjacent L101.

Tight quarters here, lots of hemostat work and a bit of cussing too, but a 
lot easier than getting inside T104.  No room for a full size 2.5 mh RF grid 
choke but found a miniature version that worked FB.  Inductance here probably not 
too critical.  Check carefully to make sure nothing shorts when the back 
section is folded up in place.  I had to shorten up one of the screws that holds 
the interconnecting cable socket in place to prevent interference.
 
Dennis D. W7QHO
Glendale, CA