Topband: Feedpoint voltage

[Gary Smith]

Another bugaboo for me to deal with; 

I have the 160 inverted L set up pretty much ready to go. I have 
about 150' of wire antenna set up somewhat similar to what you see 
here http://users.erols.com/k3mt/inv_u/u_160.htm except I have far 
more radials laid out. I will have the antenna resonant on the CW 
portuion of the band and will not be needing more range than that.

Problem is the capacitor. I have several Vacuum variables around here 
that are missing the threaded screw/adjusting attachment. I could 
work out something that would make any of these work but I do have 
one VV that has arced some time in the past (copper on glass & 
multiple light pitting from RF). It has a dedicated adjustment and it 
still has a good suck to seat back in place when it's pulled out. I'm 
thinking this would be a good one to use in that it's already damaged 
and I wouldn't mind using it outside. I checked it with a Tel Ohm 
Mike and it has about 320pf at full engagement.

The markings are: 
Vacap Corp - Union City, NJ
VVC 300 - 42 - 10
SM-B-184928
A google says it runs from 20-300pf at 10KV

I don't know the history of this VV and am wanting to run the legal 
limit through the antenna and know the real voltage is at the distal 
end of the antenna and the current is max at the feedpoint. I don't 
however have a clue as to wether a cap in series at the feedpoint 
will undergo a lot of voltage or not. Knowing the fellow (SK) who 
owned this VV before me, it surely was in a tank of a multi KW amp 
and it arced because he abused it; so in all likelihood, the vacuum 
is is probably intact. Even if weak, I'm thinking it would probably 
be all I'll need.

I have no hi-pot to test it so I'm asking for thoughts as to wether 
there's a lot of volts expected here with a Titan 425 driving it on 
160. And if a VV such as this one sounds like a worthwhile item for 
this purpose. 

Thanks

Gary
KA1J