Topband: SHUNT FED TOWER ARCING

[N4BAA - Jose Castillo]

Hello,
Shunt fed my 75 foot 45G today.

On top at 88 feet is a FORCE 12 EF230/240 on 24 foot boom.
At 76 feet is a 5 ele KLM 20M mono on 42 ft boom.
Shunt wire is #18 spaced 42 inches from tower top and bottom.
Chunt Tap is at 42-ish  feet up.


Was able to instantly put that baby at flat SWR at 1.830 with the motor 
driven 1000 pf vacuum variable cap.
Impedance after driving it to a good SWR is roughly 40 ohms.  Fired up 
the AMP and hit is with 1300 watts...no issues....

Went to dinner...came back at 6:30 PM local...(cold weather..dry 
air)...and although SWR still looks good....AMP is now tripping of line 
for some reason.
There are coils on the FORCE 12 antennas but the KLM style 20M does NOT 
have a coil across the driven elements....

Did not attempt any further "tweaking"....so...tomorrow should I TWEAK 
the tap for a more 50 ohm tap?
Pull the shunt wire out even further to attempt to raise capacitance?

Ideas?

Thanks and Happy New Year...

Jose Castillo - N4BAA