All the tests -- signal comparison and noise tests -- were done on the same band, to which the tuner was tuned (40m).
On 4/5/2012 12:23 PM, Don Wilhelm 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! >> -- 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
