I t's been shown conclusively that an unbalanced 'floating' tuner with a balun on the input does not provide better balance than one with the balun on the output. Yes, I know that there is such a tuner in the ARRL handbook and Alpha is manufacturing one. But the math doesn't lie. So unless Elecraft wanted to use a balanced network -- which would make the tuner MUCH more expensive -- I would prefer one without a balun. Then those who do not use balanced lines would not have to pay for the balun.
On 12/8/2011 8:58 AM, Oliver Johns wrote: > Wayne, > > When I talked to you briefly at the 2010 Pacificon, you seemed to say that > the KAT500 would be a "floating-L" design. That is, it would contain an > unbalanced L network, but that network and its circuit board would be > floating and not connected to the metal enclosure. You said a balun would be > put at the 50 ohm end, feeding a SO239 connector for the coax to the rig. > The floating-L could then be connected to balanced lines, or to unbalanced > ones by tying one side of it to the case at the antenna end. > > Now it seems that you are talking about a totally unbalanced tuner, with no > provision for balanced antenna feeders. Do you mean to add an external balun > on the *antenna* side of the tuner? Surely not. That seems an inherently > bad idea for many balanced lines. The impedance there will be unpredictable, > hence the need for the tuner. Not a good place for a balun IMHO. But if you > put the balun on the 50 ohm end where it belongs, then the whole enclosure > will be tied to one side of the "balanced" line, which will likely unbalance > it. > > What happened? I had hoped to put the KAT500 in a weatherproof box of my own > fabrication and use it between a balanced line to the antenna and a coax feed > back to the rig. It could live out near the antenna, where it belongs. > > 73, > > Oliver Johns > W6ODJ > > > On Dec 7, 2011, at 5:22 PM, Wayne Burdick wrote: > >> We originally had two antenna jacks on the KAT500, with one of them >> switchable between balanced and unbalanced. >> >> Recently we decided that a third antenna jack would provide greater >> utility overall. (In my case, I'll be keeping a dummy load on the >> third jack.) All three jacks will be unbalanced (SO239). >> >> We're hoping to add a high-power, high-performance balun to our >> product line sometime next year that will serve the needs of those >> using balanced lines. >> >> 73, >> Wayne >> N6KR >> -- 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
