Ive never owned a vacuum variable. What I have been using for decades are very large air variables hung from a stick, or tree or whatever and I cover it up with a 2L pop bottle* with the bottom cut out of it. Fix in place with rope, string, tape, fishing line, whatever.
I cant take credit for this trick (I dont think anyways) as I have seen hardline coax splices made much the same way many moons ago at the famous VE1ZZ antenna farm. Its pretty rare for this to ever fail, or even have wx issues. Of course if you get screaming high winds with freezing rain going horizontal it is possible to get a little frozen moisture up inside the bottle and then onto the plates of the cap, but transmitting a few times usually solves the problem. *would the equivalent of 2L pop bottle be ½ gallon soda bottle? Mike VE9AA A vacuum variable for L impedance matching is unnecessary. Vacuum variable capacitors leak eventually. It take a long time for them to go through their ranges and you have to have the mechanics outside if you perform remote tuning, to sense or count turns to track when the v.v. is nearing its maximum or minimum. It is far far easier and faster to use an air variable that rotates freely. You only need to keep it sheltered. Elevated radials are fine provided they are high enough to be decoupled from earth, which for most hams is difficult to accomplish on 160 m. 73 Rob K5UJ Mike, Coreen & Corey Keswick Ridge, NB _________________ Topband Reflector Archives - http://www.contesting.com/_topband
