Also note that in the case of the KPA500, we will be matching SWRs of 10:1 or less, which results in less loss for the short coax choke mentioned.
73, Eric www.elecraft.com On 12/12/2011 2:00 PM, Ron D'Eau Claire wrote: > I would avoid coaxial cable in any situation where there can be a large > impedance mismatch because of just the losses mentioned. Even though low > power might not burn up 3 feet of coax, that's still a chunk of power thrown > away. > > The ideal CM choke at the OUTPUT of a tuner feeding a balanced line would be > made of open wire line. The old air-core chokes did just that but, to have > the choking impedance needed, they are physically B-I-G, especially if used > on 80 or 160 meters. Some look like 'steampunk' art with huge coils > occupying a whole wall, not unlike what one sees in some photos of early > spark transmitting stations. > > A parallel pair of wires wrapped on suitable toroid cores would be my first > choice today, but never with coax between the choke and the matching > network. With a little ingenuity one can make a very clean, neat open wire > line installation running across a ceiling using small insulators attached > to the ceiling if the operating position is far from the point of egress to > the outside. > > 73, > > Ron AC7AC > > -----Original Message----- > > Dean > > Nice analysis of the issues. K9YC also presents baluns done with wire pair > rather than coax, RG213 or otherwise. Might not they be a better solution > than coax when constructing a CM choke for driving windowline? > > Jim ab3cv > > ______________________________________________________________ > 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 ______________________________________________________________ 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
