That is a really tough antenna to match for 160 Stephen. The classic way to use an 80 meter dipole on 160 is to short the feed line at a ground point and feed it with the center conductor with the braid to the best counter poise you can manage. This will make you a T topped Marconi which will probably tune for you. Willis 'Cookie' Cooke K5EWJ
________________________________ From: Stephen Prior <s...@sjprior.fsnet.co.uk> To: elecraft <elecraft@mailman.qth.net> Sent: Sun, January 2, 2011 1:31:06 PM Subject: [Elecraft] [K3] KAT3 and 160 with 40m long doublet I have only just recently added the KAT3 and I'm very impressed with it, but given the praise heaped upon it by others I'm slightly surprised that the best VSWR I can get on 160m is about 8:1. The antenna is approximately a doublet which is a half wave long on 80m I say 'approximately' as it's slightly off-centre fed. I have about 7m of 300 ohm slotted down from the feedpoint and then into a coaxial choke at roof level for the remaining 10m into the back of the K3. Substituting the straight connection for a 4:1 balun (Guanella) at the transition between the slotted feeder and the coax helps slightly but not by much. Unfortunately I don't have a vector analyser, so I have no idea of the nature of the reactance that the K3 is seeing. However, given the wavelength involved, I would need to add a very significant length of coaxial cable if I were to swing the point around the Smith Chart. I have tried to manually tune the KAT3, but unless I am missing something, I am am not able to change the L and C values at the same time as transmitting, so it's a very tedious process. Tomorrow I may well add some extra wire to hang vertically down from the ends of the doublet. In the meantime I would be pleased to hear any comments. Happy New Year! 73 Stephen, G4SJP ______________________________________________________________ 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 ______________________________________________________________ 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
