I have a full size 80 meter delta loop that is vertical, hung from a support on my tower at the 75 foot point. The shape is not ideal (too much horizontal but I can't do any better). I feed it with 450 ohm line at the 0.64 wave point down from the top. The antenna is then tuned with an AT-Auto (Palstar) and I've used other tuners as well. This antenna does not tune at all well on 160. The Q is out of sight (very sharp) and if you can get a match (I would with an old Murch but not the AT-Auto) it was only good for a few kHz before you had to retune and tuning was very touchy.
I never tried lengthening the feedline -- I just put up a true 160 meter antenna, a Double-L which works OK. After three years of very casual operating, I made DXCC on top band. Pete, W1RM -----Original Message----- From: Rick McClelland, AA5S [mailto:[email protected]] Sent: Thursday, January 05, 2012 10:14 AM To: [email protected] Subject: [Elecraft] Horizontal Delta Loop Questions Hi, I'm a CW operator who dwells in the lower end of the HF bands. My current antenna is a 200' horizontal delta loop 40' high, fed with 87' of 450 ohm ladder line. This connects to a 4 to 1 balun (common mode choke?) which is attached to my Dentron Jr. Monitor tuner via 5' of RG213. Looking at a spreadsheet, I see that a full wave loop for 80 meters is 287' and 143.57' for 40 meters. A hypothetical question to the wise ones on this list is would I expect any practical improvement in performance of my antenna system (on 40 meters and above) by reducing my 200' delta loop to 143.57' and feeding it with 71.78' of ladder line so that the sum of the antenna length plus twice the ladder line length is 287'? This seems to make theoretical sense since the entire system would be resonant at 7mhz and integral multiples thereof. However, the performance of my current 200' loop appears to be quite good from 80 to 6 meters and my small tuner matches whatever impedance this system is presenting to it so I'm hesitant to take a pair of snippers to my antenna. I would like to increase the length of the loop to 287' feet and feed it with 71.78' of ladderline but that is another story. Also, would I expect to be able to tune any of the these three antennas on 160 meters if I were to purchase either a KXAT100 or KAT500 tuner which presumably have a wider tuning ranges than the Dentron Jr. Monitor tuner? Rick McClelland, AA5S Fort Collins, CO ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
