Topband: alternative to vacuum variables

[Gary Smith]

I don't know much antenna theory, ask me something regarding human 
biology & I might be a better authority. 

However, back when I lived in IL in the early 90's, I used to have a 
tower and not enough space to put a good radial field down. What I 
did to get on 160 was make a shortened delta loop with the apex at 
the top of the tower and center fed at the base, held off the tower 
by around 7-12". 

I had a relatively small, and inexpensive vacuum variable at the 
feedpoint at the bottom and ran a wire up the tower held off by 
spacers from that feedpoint till the capacitance was sufficient that 
at the least capacitance from the VV, I was 1:1 at 1.800.

I had a servo attached to the VV and enclosed everything in a plastic 
mailbox and mounted that at the tower. I had the matching servo in 
the shack and was able to adjust that small VV to give me 1:1 across 
the entire 160 meter band. I believe the VV was a 5KV 300pf variety.

This may not be what you need to do with your setup but it allowed me 
to use a cheap VV and surplus servos to give me a perfect feedpoint 
match and I had no issues with my old 77SX with this setup. And when 
running QRP I had fantastic results. Wish my current Inv-L with 60 
130' radials worked nearly as well.

Gary
KA1J