Hi David, I know a little about this. The T-match provided manufactures with a way to get more impedance matching range out of fewer components in the box. Its basically a step-up/step-down matching network. Its marketing value is added versatility....hence the "versa"-tuner became quite popular.
Most auto-tuners are L-networks. The MJF-balanced tuner actualy puts the caps in series, so its kind of a double T-network, and very effective for wide-range tuning needs, from what I hear. It uses a 15" long coax lenght with beads as a choke to minimize RF from the coax shield. The L-network and T-network are both unbalanced configurations. The Johnson box was a balanced configuration, and was superseded, for the most part when baluns started to be put into unbalanced tuners to convert the unbalanced to balanced condition. The J-box was an awesome balanced tuner, but with a limited matching range. Many hams in the days of the J-box operated only on one or two bands, which the J-box easily facilitated. Duane N1BBR Can anyone point to why the single coil Z match wasn't commercialized rather than the T match? (Perhaps it's a historical thing and manufacturers just copy each other, notwithstanding the Johnson Matchbox of course, which is no longer produced.) David -- bw...@fastmail.net ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
