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
