Interesting! The balun I made is just a basic core type current balun modeled after the one listed here (but made with high temp wire inside teflon tubing):
http://vk5ajl.com/projects/baluns.php#current On Thu, Apr 5, 2012 at 2:15 PM, Adrian <vk4...@bigpond.com> wrote: > The external balun you are using is probably better than the one built into > the tuner. An English ham did research some time back and found using a > 1:1 > current balun less lossy that a 4:1 or others, despite the line mismatch > the > tuner made up for it with tested less total loss. > > With a well designed tuner/balun combo the circulating current is much > less, > and it is only the resistance component that provides loss, not inductive > nor capacitive. > > vk4tux > > > -----Original Message----- > From: elecraft-boun...@mailman.qth.net > [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Matt Murphy > Sent: Friday, 6 April 2012 5:53 AM > To: d...@w3fpr.com > Cc: Vic K2VCO; elecraft@mailman.qth.net > Subject: Re: [Elecraft] K3 power reduction due to high SWR > > One related question, when speaking of the efficiency of a balanced > feedline > + balun and tuner, what would be a best/worst case scenario for the loss > introduced by the balun+tuner? Would loss vary significantly by frequency > for a nonresonant antenna? I'm trying to develop an intuition about the > lossiness of the tuner+balun compared to, say, 50' of RG213. > > I've opted to use a 1:1 balun at the end of 450 ohm ladder line, then a > short length of coax into a TenTec 229 tuner. In the informal test that I > performed, the homebrew 1:1 balun + coax jumper improved the performance of > the antenna compared with connecting it directly to the balanced line > connectors on the back of the tuner. > > 73, > Matt NQ6N > > > > On Thu, Apr 5, 2012 at 12:23 PM, Don Wilhelm <w3...@embarqmail.com> wrote: > > > Vic, > > > > Where was the frequency of the GDO with respect to the band the tuner > > was set to? If it was below the band of interest, I would expect > > something like that - the T-Network is a high pass filter. > > > > 73, > > Don W3FPR > > > > > > On 4/5/2012 12:28 PM, Vic K2VCO wrote: > > > Speaking of balanced lines and tuners, I recently did an experiment > > > that > > surprised me. > > > > > > I have a dipole fed with 600-ohm open-wire line (and some window > > > line > > indoors). I usually > > > tune it with a Johnson Matchbox, a fully balanced link-coupled tuner. > > > > > > I was lucky enough to get my hands on a massive, high-quality > > > edge-wound > > rotary inductor > > > in a well-made aluminum enclosure. So I built a high-power T-network > > tuner with it. I > > > purchased a good (and expensive) 1:1 balun designed for use after a > > tuner from DX > > > Engineering, and compared the T-net + balun to the Matchbox. I > > > didn't > > notice any > > > difference in the strength of received signals between the tuners. > > > > > > But here is the surprising part: I expected that the Matchbox would > > provide better > > > balance, which would reduce radiation and pickup from the feedline. > > > To > > test this, I > > > coupled a grid-dip oscillator to the feedline about 20 feet from the > > tuner. > > > > > > To my great surprise, the signal from the oscillator was much weaker > > with the T-network + > > > balun than with the Matchbox! > > > > > > Signals the same, 'noise' weaker. So much for the need for 'truly > > balanced' tuners! > > > > > ______________________________________________________________ > > 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 > > ______________________________________________________________ > 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
