Bob, To avoid the trips up and down the tower in the winter merely add an Omega cap from the shunt to ground, You can start with a bread slicer and replace with a fixed mica later when yu find what you need. IMHO I would replace, when you can, the shunt wire with a three or four wire cage feed as this will broaden out your B/W response significantly. If you don't want to try an Omega match then i recommend a CLC network rather than a straight series Cap.
Herb, KV4FZ On 12/11/2011 1:21 PM, Bob Garrett wrote: > Hello Topbanders, > > It is getting cold in the Northeast and as I get older, I dislike the cold > even more. > > In April of this year, I replaced my Cush craft D40 40 meter rotable dipole > with an OptiBeam OB-4030 dipole for 30 and 40 meters right at the top of the > mast. The overall length of the antenna is about ten feet longer and I am > assuming that it has added some additional capacitance to my 100 foot shunt > fed tower with a Cush craft X7, A3WS, 5 EL M2 6 meter yagi and the new > OptiBeam dipole. > > My match on the tower went from 1.0 x 1. To 1.9 x 1 after I installed the > new antenna. In terms of loss, this isn't a huge change but my amplifier > doesn't like the change. Before I spend a lot of time running back and > forth to the tower making random changes, any thoughts as to what I can do > to improve the match. I'm currently using one series capacitor 1000PF for > the matching network. I have attempted to adjust this capacitor but it > looks like the 1.9 x 1 is the low point. Perhaps some thoughts - increase > or decrease the spacing of the shunt wire? Move the connection up or down > on the tower? > > Before I get to crazy, just wanted to look to the base of knowledge on this > reflector for your input. > > 73 and tnx in advance. > > Bob K3UL > > > _______________________________________________ > _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK