Wonder if that FCP would be mo betta for my 43' vertical with three 25' top hat wires mounted in a NORD sort of configuration, angled down at about 45 degrees.
I have 40 counterpoises- 25 are elevated about 3 feet above ground and 15 are lying on the ground - and the length varies from 15 to 75 feet (I use the antenna for 160 by switching a loading coil; switch it out for the other bands). Thoughts? 72, Jim Rodenkirch, K9JWV > Date: Fri, 9 Dec 2011 19:24:43 -0500 > From: [email protected] > To: [email protected] > Subject: Topband: K2AV 160m Folded Counterpoise Antenna - New Details Posted > > > Hullo folks. FWIW..... > > I mounted the FCP on my "inverted J" which is about 60 up, 40 over, and > another 40 to 50 over again. About 150 feet of wire on the radiator. > > The FCP and transformer box are mounted about 7 feet up. Sent photos to > W0UCE since I still have the step ladder conveniently located. > > With 880pf of capacitance in series it is resonant right about 1830. The > autotuner in my ft-920 can tune it easily down at 1800, and runs into > trouble at 1860 up. Have not yet given the K2 tuner a look at the load. > > Using the Elecraft K2 S-meter as a field strength meter, sense antenna a > dummy load on a 7 foot jumper, full attenuation/no preamp, the OLD > antenna set up registered S5 on the K2 with 100w going into the antenna > from the FT-920 at its 1:1 SWR point. [K2 in the shack about 75 feet > from base of antenna and old antenna radials described below] > > After removing the elevated radials(they were in the way) and installing > the FCP system, yesterday I found that: > > 20w into the antenna from FT-920 now registers S5 on K2 > 40w into the antenna from FT-920 now registers S5 plus one bar on K2 > 60w into the antenna from FT-920 now registers S5 plus two bars K2 > 100w into the antenna from FT-920 now registers S9 (S5 plus three bars) > > I'm pretty sure my K2's S-meter is not well calibrated so there is not a > real quantitative measure there. But the new antenna is a lot better > than the system it replaced. (Note: The K2 bar graph has three bars > between s5 and s9.....> 5||9) > > There are still improvements I can make. There is a large coax > choke/balun wound with rg-58 that I'll be replacing with a much shorter > rg-8 jumper. > > The original crummy antenna(before FCP installed): > The old radials consisted of 8 radials about 6 feet above ground, all of > 35+/- feet in length. There were an additional 20 radials of various > lengths from 16 to 30 feet long. All were tied together at the bottom > of a coil, and the feedline ground tapped the coil where it provided the > best match. The radiator was the same ~150 feet of wire with the same > 880pf of capacitance in series. (A mix of 150pf and 82pf panasonic 3kv > ceramics in parallel). The 82pf caps will be switched out to move the > match should the relays prove capable of the task. > > The old set up allowed me to run US stations during ARRL 160m in 2010, > but never worked much dx or west coast with 100w. > > I wanted to get it all installed before ARRL 160m this year, but that > didn't happen. But maybe my 100w will be less like QRP for Stew Perry. > > For my own part, the 30 elevated radials were a maintenance nightmare, > although they were producing better results than 8 uniform length > radials. But every falling tree limb snagged one of them. The FCP > lowers the odds of being hit by a factor of 15. That should cut down on > radial repairs. Cha-Ching :) > > Other random thoughts...... > My installation of the FCP would have been easy to tune by trial and > error. With the antenna long, a large value air variable could be used. > Tune it to the sweet spot, measure the value of the air variable, and > replace it with the fixed value. I expect my own spark gap to be between > the vertical and the capacitors. > > Thanks very much to K2AV for his help with the project. Test drive > for Stew Perry. > > 73 de w4kaz > > > > _______________________________________________ > UR RST IS ... ... ..9 QSB QSB - hw? BK _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
