Hello George, Many thanks for your comments which I shall have to read later - Daughter + Dog arrived about 30 minutes ago. First licence late 1946 - a hunted DX morsel - but manners were better then !!
73 Geoff GM4ESD ----- Original Message ----- From: "George, W5YR" <[EMAIL PROTECTED]> To: "Geoffrey Mackenzie-Kennedy" <[EMAIL PROTECTED]> Cc: "Elecraft Discussion List" <[email protected]> Sent: Friday, August 06, 2004 5:19 PM Subject: Re: [Elecraft] Performance of baluns. > The current balun can be readily demonstrated to provide equal and opposite > currents to highly unbalanced loads. A simple test is to connect a balun to > a load consisting of a 50 ohm resistor connected to a common or ground place > and similarly a 100 ohm resistor. Measurement of the r-f voltage across the > resistors will show that equal currents are being forced through each as the > voltage across the 100 ohm resistor will be twice that of the 50 ohm > resistor. > > Roy Lewallen W7EL and Walt Maxwell W2DU have both discussed this test and > Roy described a test fixture for demonstration. I have built the fixture and > carried out the test with a simple W2DU bead balun and found almost perfect > balance with equal currents being delivered to unequal load resistances. > > Simple 1:1 current or choke baluns such as the bead baluns are relatively > insensitive to load impedance. I use them to transition from ladderline > feeding multiband balanced antenna loads to coax to enter the shack to the > tuners. The load seen by the baluns varies widely with band as would be > expected. > > The Elecraft 4:1 balun is unique in its design and is able to provide an > approximate 4:1 transformation over a wide range of frequencies and load > impedances. Thus there is little need to restrict its connection to the > input of a tuning unit. > > Teacher wasn't wrong, Geoffrey - it has just been a long time! > > 73, George W5YR (58 years a ham the end of this month) > Fairview, TX > [EMAIL PROTECTED] > http://www.w5yr.com > > > > ----- Original Message ----- > From: "Geoffrey Mackenzie-Kennedy" <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]> > Cc: "Elecraft Discussion List" <[email protected]> > Sent: Friday, August 06, 2004 10:47 AM > Subject: [Elecraft] Performance of baluns. _______________________________________________ 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
