Don,
You are of course correct about having a balanced tuner with split stator capacitor, center tapped inductor, swinging link, and series capacitor with the link, and other variations that have been around since radio's were powered by steam. You leave out one important thing though that gets picked up by those who market tuners, and that is for every dollar spent on a commercial amplifier, you need to spend half of that for a tuner suitable for the job. There are tuners out there for more than a thousand bucks that still put the balun on the load side of the tuner. This does not have to be, and one solution dreamed up by folks wanting higher profit margins, is to take a flawed design, and keep scaling it up until it works. This is kind of like building a 10KW tuner for a 1 KW job. Maybe I am exaggerating a little, but not really that much. There are tuners that put the balun on the input side of the tuner where when the conjugate match is obtained, the balun only sees a resistive load at 50 ohms. These can use a conventional "universal transmatch" design with the ground return floating (common to one side of balanced input, and one side of the balanced output). I made a tuner like this, and used it for years. It worked great on 160-20 meters, but the compromise design starts to show imbalance above 20 meters. I am pretty sure MFJ, and a few others do have a few tuners designed this way. It is also refreshing to see MFJ marketing a line of tuners that are somewhat similar to a Viking Matchbox. I still think that those kilo-buck + tuners with a big balun on the output are often used in ways that are not very efficient when the load is highly reactive, and these will act exactly like Ron described below. Regards, Jim Candela WD5JKO -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of [EMAIL PROTECTED] Sent: Wednesday, April 19, 2006 11:54 AM To: Discussion of AM Radio; amradio@mailman.qth.net Subject: Re: RE: [AMRadio] Baluns for Zepp Antenna Thanks Don You make a good point everyone should consider. I have noticed a teeker-totter effect with Toroids and un blanaced reactive feeders like 450 ohm ladder line. Get the SWR nulled out and in one minute it starts to climb again as a toroid saturates, null it out again and it happens again. Your tuner suggestion is obviously the best but a few of us like to see if we can noodle it out with home brew stuff. Thanks again for your comments Ron From: "Donald Chester" <[EMAIL PROTECTED]> Date: 2006/04/19 Wed PM 12:43:25 EDT To: amradio@mailman.qth.net Subject: RE: [AMRadio] Baluns for Zepp Antenna >From: <[EMAIL PROTECTED]> > > >Simple Coax Balun > >www.southgatearc.org/techtips/coax_balun.htm > >Toroid Balun > >www.rason.org/Projects/balun/balun.htm > >Romex and PVC under $3.00 Balun > >www.bloomington.in.us/~wh2t/balun.html > All those baluns operate on the assumption that the balanced load is primarily resistive. If the load is highly reactive, as is often the case with open wire resonant feeders, the balun may not function properly, especially the toroidal types at high power. I still prefer an honest-to-god balanced tuner, with split stator capacitor and symmetrical balanced coil. Don k4kyv ______________________________________________________________ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb Ron Weaver - W6OM Web Site: www.qsl.net/w6om ______________________________________________________________ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.4.4/318 - Release Date: 4/18/2006 -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.4.4/318 - Release Date: 4/18/2006