Hmm, the link didn't take! The info is on QRZ.com/VE6WZ 73, Stew K3ND From: GALE STEWARD via Topband <topband@contesting.com> To: "topband@contesting.com" <topband@contesting.com> Sent: Tuesday, October 11, 2016 11:59 AM Subject: Re: Topband: 80m rotatable dipole load coil questions Here's a link to a 80M yagi designed and built by VE6WZ. Some good loading coil info. 73, Stew K3ND
80m 2-el Yagi | | | 80m 2-el Yagi | | | From: Grant Saviers <gran...@pacbell.net> To: Ray Benny <rayn...@cableone.net>; "topband@contesting.com" <topband@contesting.com> Sent: Tuesday, October 11, 2016 11:35 AM Subject: Re: Topband: 80m rotatable dipole load coil questions From a coil loaded 80m 2L yagi (bought JKantennas) and 80m rotatable dipole I built and reading here are some thoughts. My rotatable 80m Tornado loaded 86' dipole at 100' doesn't have much of a pattern, height is everything and at about 130' or so they really start to play. The beam is at 157'. Element gap isn't too important - wide enough to stand the voltage, strong, and UV durable. 2" is ok. A fiberglass solid rod with paint would work, or a UV resistant plastic sleeve over the FG. No steel or SS near the coil if possible. IMO, there is very little loss difference with 1/4" tubing Cu vs Al. Good electrical joints are probably more important. Coil L/D ratio about 1 and turns spaced tubing diameter seems to be about optimal for highest Q. Any form will reduce Q, so best to avoid them and make the coil self supporting. I use http://hamwaves.com/antennas/inductance.html for a coil calculator, it gives you every value you might want. Many other issues - truss connections, 3 way truss per Lesson's designs, wind load calcs, etc. My dipole truss is 2 phillystrans up to a 5' wide crossbar 5' up the mast. So far no problems, but in a treed area with modest wind loads. YagiMech predicts 85 mph survival w/o truss. I'll send a coil picture offline. Grant KZ1W _________________ Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband