Thanks for all the responses. One respondent recalled hearing of success with a similar setup on the Towertalk reflector. By searching the archives for "shunt bands" I found an "existence theorem" at:
http://lists.contesting.com/archives//html/Topband/1997-12/msg00194.html I followed the prescription to connect the gamma wires for the two bands to different tower legs, then realized that I had made a serious mistake by failing to reduce the tower-to-gamma wire spacing for the 80m feed. With these two changes, I am able to get the desired behavior on both bands, by switching from one series cap to the other. 73 -- Brian -- K1LI On Tue, Oct 25, 2011 at 10:07 AM, Brian Machesney <[email protected]>wrote: > Gang, > > I have an 80-ft tower topped by an KT34XA (elements insulated from 32-ft > boom) and 40-2CD (only reflector electrically connected to 22-ft boom). I > have 8 x 50-ft lengths of 4-ft wide welded, galvanized steel fence for a > ground screen. No other radials. > > I have successfully matched this on 160 with about 350-pF series capacitor > to a 45-ft #12 gamma wire spaced about 3-ft from the tower. > > I also want to feed the tower on 80. I have been hoping that the 160 gamma > wire would "disappear" electrically when it is open-circuited. Given the > complex configuratino of the GAP vertical antennas, this may be but a faint > hope. I'm having trouble creating a good match on 80 with a simple gamma > feed scheme. > > Has anyone on the reflector tried to feed the same tower on two bands? > > Please reply off-reflector. > > Thanks and 73, > > Brian K1LI > _______________________________________________ > UR RST IS ... ... ..9 QSB QSB - hw? BK > -- -- The hallmark of a successful parasite is that it never kills its host -- _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
