It is a common misconception that a 4:1 balun is the best choice to feed a tuned balanced line. The assumption is often made that this is appropriate because the characteristic impedance of ladder line or open-wire line is higher than the 50-ohm coax that's connected to the balun's input.
Actually, since the tuned line is being operated at a high SWR, the impedance seen by the balun will vary all over the map. It may be very high or very low. This is a very tough job for the balun, and in some circumstances it can be quite lossy. This is why a real balanced tuner is better than an unbalanced tuner followed by a balun. A 1:1 balun is likely to have lower losses in this application, although there might be combinations of frequency and line length where a 4:1 is better. I hope that Elecraft is planning to make their balun either 1:1 or switchable. On 12/7/2011 11:35 PM, Gary VK4FD wrote: > Liked it better when it had a balanced line connection as part of the unit. > > There are plenty of 4:1 Baluins on the market already. > > Without knowing what this Auto-Tuner will do it is indeed hard to judge > whether it will be a product that rates a "Must Have" over "just another > ATU"....???? > > > YMMV > > Gary > > > VK4FD - Motorhome Mobile > Elecraft Equipment > K3 #679, KPA-500 #018 > Living the dream!!! > -- Vic, K2VCO Fresno CA http://www.qsl.net/k2vco/ ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
