There may be no difference in efficiency between putting the balun at the input or the output of the tuner if you are operating into a nice 50ohm resistive dummy load, but the situation changes if you are operating into an antenna fed with ladder line on which there is a high SWR. In this case, the high SWR can cause high currents that saturate the ferrite core in the balun, and causing non-linearity and producing heat losses. This is why it may be preferable to locate the balun at the input of the tuner, where the SWR on the transmission line is low, and "float" the whole tuner. However, as Don mentioned, this can present difficulties if the tuner is not a balanced design.
73, Matt VK2ACL On 29/09/2012, at 9:06 AM, Andrew Moore <andrew.n...@gmail.com> wrote: > Great; thank you for the trivia, very helpful. I figured it had already > been considered and that there was a good reason for the current > configuration. > > The BL2 following the KAT3 was exactly one option I was considering. I've > read about several cases in which ops had success, but read others in which > the balun was heating perhaps due to excessive reactance on the antenna > side. Reactance is likely dependent on the frequency/band and several > factors in the antenna system which could explain the mixed results. > > I think I will try this approach and enjoy the experimenting. > > All: Not looking to turn this in to an OT antenna theory thread, but if you > have specific experience with this configuration, I'd like to hear (KAT3 to > BL2 to ladder to simple dipole). > > Thanks, > --Andrew, NV1B > maineware.net > .. > > > On Fri, Sep 28, 2012 at 6:43 PM, Don Wilhelm <w3...@embarqmail.com> wrote: > >> Andrew, >> >> A bit of 'trivia' first: >> That was "supposed" to be a solution in the KAT500 tuner. The initial >> design put the balun on the input of the tuner, and attempted to "float" >> the rest of the tuner while trying to maintain balance. >> >> There were problems with maintaining balance through the rest of the >> tuner, while studies indicated there was no efficiency difference between >> the balun at the input vs. the balun at the output, so the design was >> changed to an unbalanced design driving (if required or desired) a balun at >> the output of the tuner. >> >> "trivia off": >> >> So more specific to your question, a balanced output from the K3 KAT3 can >> easily be obtained by using an Elecraft BL2 on the output side of the KAT3. >> >> > ______________________________________________________________ > 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
