Hi Vic Yes, I didn't mention it, but there is a 1:1 balun inside the switch box before the feedline exits on its way to the rig.
After listening to K9YC at our NCCC meetings, I think I need to increase the impedance of this 1:1 choke balun though. It's a bit undersized from his point of view :-) 73, Bob N6WG ----- Original Message ----- From: "Vic K2VCO" <[EMAIL PROTECTED]> To: "Robert Tellefsen" <[EMAIL PROTECTED]> Cc: <[EMAIL PROTECTED]>; <[email protected]> Sent: Wednesday, March 12, 2008 9:59 AM Subject: Re: [Elecraft] K3 Multi-Band antenna thoughts > Robert Tellefsen wrote: > > > To make antenna matching easier for the TX, I have a > > homebrew relay box that adds in various lengths of more > > 450 ohm window line to bring the feedpoint reactance > > down to close to zero. This gives the ATU a chance to > > match easily and gives the best 2:1 swr bandwidth. The > > single band antennas are coax fed, but still switched > > through the relay box. > > I do something similar, although I use inductors and capacitors rather > than pieces of line. This is very important to make a balun connected > between the balanced line and the coax efficient. I conducted a series > of tests in which I measured the temperature rise in the balun -- a sure > indicator of losses -- when the mismatch was primarily resistive or > reactive. Reactance is poison for balun efficiency! > > And yes, you need a balun to reduce noise pickup, line radiation, and > rf-in-the-shack. > -- > 73, > Vic, K2VCO > Fresno CA > http://www.qsl.net/k2vco _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
