[Collins] 312B-4 wattmeter query

[Chris Kepus]

I have 2 B-4 units: one winged, one meatball.  

I haven't used either for some time so decided to test their wattmeter
function before putting them "on-line".  Used a Valiant transmitter for RF
power into a Bird into a 312B-4 into a Heathkit Cantenna. The results were
very disappointing. 

The CCA site had nothing in the way of info to help.  The Collins list
archives back through 2007 were also quiet on B-4 coupler problems or
rebuilding. Google didn't turn anything up. 

Before I plunge into these units, I hope someone familiar with the B-4 can
suggest some possible causes of the symptonms and/or the most efficient way
to trouble shoot my #1 and #2 B-4's problems.  

First up to test was #1, the winged B-4.  The meter pointer at rest (no
power in) is a cat whisker above zero.  With power applied, the meter
pointer moved to indicate 75 watts (200 W mode) while the Bird indicated 110
watts. Rapping the meter with a knuckle caused the meter pointer to advance
to roughly 140ish watts. When power was removed, the pointer did not return
to zero but stopped at about 30.  Hmmmm.  Rapping with a knuckle caused the
pointer to return pointing near zero.  Repeated this about six times hoping
the meter exercise would help but no joy. It appears the meter has a
"sticky" movement. 

Second to test was #2, the meatball B-4.  At rest (no power in), the meter
pointer is at zero.  With power applied (110 watts on the Bird), the meter
pointer pinned above 200 watts (200 W mode).  Same result in 2000 W mode.
Since the coupler is bi-directional with 200 and 2000 watt ranges for
reflected power, I was tempted to input the power on the antenna side to see
what the meter would read. Nothing on the schematic looked to be in harm's
way if the input/output were flipped.  Anyone?  

As Al, W8UT, said in a very similar circumstance in 2008, "Any help greatly
appreciated."

Thanks es 73,
Chris
W7JPG