Observational note on radials on the ground. My 43x130 foot inverted-L requires more inductance in the summer for resonance. I see the change about a month after ground freeze-up (but that may vary with moisture content of the ground). Fall usually exhibits saturated ground due to the rainy season, whereas spring is typically dry after the thaw (May is our sunniest month).
My 50-70 foot chicken wire radials are short for 500-KHz but do have a higher velocity factor (not measured). I do not have property for 930-foot radials! More metal under the inverted-L would be better but this is my practical limit. I have not spent much time looking at 160m and 80m tuning of the antenna, but will, eventually. The original design was for a 80m half-square but comparison with the inverted-L does not make it desirable enough for the complication in design. The antenna hears well (Buffalo, NY on 511-KHz from Alaska). I will begin my winter beacon transmissions later this week (WSPR on 501-KHz, 4.15w ERP). The use of a 120-foot radial (shield of my VHF Heliax cable) makes the inverted-L near to a tuned counterpoise on 80m with the elevated 130-foot top wire of the inverted-L (in fact the top is too long when you add the 43-foot vertical wire). I'm sure there will be some interesting impedances with this antenna as frequency is moved. Fortunately, the base coil can be adjusted using taps to find resonance. Impedance match is a separate issue. Before adding a base coil I could load the inverted-L on 80m using an antenna tuner at the radio. But this would have high SWR on the coax with additional loss. On 500-KHz I have Z = 53 +j0 on the coax by tapping above the grounded end of the base coil. 73, Ed - KL7UW, WD2XSH/45 ====================================== BP40IQ 500 KHz - 10-GHz www.kl7uw.com EME: 144-1.4kw*, 432-100w*, 1296-testing*, 3400-winter? DUBUS Magazine USA Rep dubus...@hotmail.com ====================================== *temp not in service ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
