I tested the endfed from myantennas at 1 kw. The transformer was only warm so no significant losses there. The feeder was RF hot so a toroid choke was added. Cable no longer hot and toroid cold. SWR low on many bands. So the only significant losses could have been through the ground.
This is obvious after a bit of thought. A vertical or inv L ( or low inv V) needs either good ground or lots of radials for small ground losses. With endfed, there is one radial, the feeder. So excellent performance by the beach, not bad in good ground, so so in poor ground. Ignacy On Nov 21, 2017 7:58 PM, "Erik Basilier" <ebasil...@cox.net> wrote: Ignacy, For an end-fed wire, I would see the possibility of power losses not only in the feed feeder, but also in the tuner, the transformer, and the effective counterpoise path. For low counterpoise losses, small counterpoise current is desirable, which means a high antenna impedance. When a long counterpoise wire is needed, and when that wire is close to the ground, I would also expect ground losses from the counterpoise current interacting with the ground, in addition to the ground losses caused by the antenna wire interacting with the ground. When the feeder (outside or shield)-tuner-radio path carries all or part of the counterpoise current, I would not rule out the possibility that the possibiility that the resistance there is sufficient to cause losses significant enough to affect overall efficiency of the system. That is why I would like to compare like antennas with different feed systems. Of course antenna wire configuration is the most important thing to determine overall performance, but when putting up a long wire, I usually start with the support structure that already exists, or that I can put up most easily. 73, Erik K7TV -----Original Message----- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Ignacy Sent: Tuesday, November 21, 2017 5:07 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] KX3 Field Ant. for 80/40/30 Antenna performance does not depend on how it is fed (if feeder losses are low) but on height and ground type. For KX3 with AT, any special length makes little sense, especially in portable conditions. KX3 matches most random wires, and KX3 with 4:1 balun matches any wires. Lack of balance is not too important with battery operation. I try to make random wire + counterpoise at least 1/4 wave on the lowest frequency for reasonable efficiency. For 1.5 KW, an endfed with a 49:1 or so transformer makes lots of sense as wideband tuners for QRO are rare, expensive and heavy. "Myantennas.com" perfected a transformer that has very small losses and does not self-destroy at high power. But in inv V configuration, it is way down from a flattop. Ignacy, NO9E -- Sent from: http://elecraft.365791.n2.nabble.com/ ______________________________________________________________ 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 Message delivered to ebasil...@cox.net ______________________________________________________________ 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 Message delivered to arch...@mail-archive.com
