A balanced version of the "T" network is a physical monstrosity requiring that both ends of the capacitors float, but is possible. The T network has the greatest matching range, but suffers from false matches resulting on high circulating currents in the tuner.
A balanced "L" network should not be difficult to produce, but if I may, I would like to put in a plug for my favorite balanced tuner which is IMHO is the old fashoined parallel (or series) resonant tank circuit using a link coupler. No balun required, but it does not lend itself easily to band switching. As a single band tuner, it is the ultimate IMHO, and the venerable Johnson Matchbox was an attempt to make that basic circuit bandswitchable. The Matchbox has some limitations in the matching range it can handle. My Johnson Matchbox will only be pried from my hands over my "cold dead body" - I do not use it much, but it really is handy for creating artificial antennas with SWR in the workshop, and it works quite well as a bandpass filter when that is needed. 73, Don W3FPR On 11/26/2011 6:48 PM, Joe Subich, W4TV wrote: > On 11/26/2011 6:00 PM, Vic K2VCO wrote: >> The balanced output is not referenced to the case. So the balun is >> functional when feeding a balanced line, not shorted as you suggest. > You are correct, that the balun is not shorted when feeding a balanced > antenna. However, in that configuration it will *only* function as a > common mode choke (if it is not constructed as a voltage balun). > > Any antenna connected to the "balanced" terminals will still not be > truly "balanced" as it is not possible to generate a balanced output > at the output of an unbalanced network by forcing balance at the input > of that network. It is quite likely that a "balun" at the input of > an unbalanced network will only increase circulating currents (and > losses) in the network. > > 73, > > ... Joe, W4TV > > ______________________________________________________________ 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
