Dave, did you use an antenna analyzer? I've tried it using two ATU's to evaluate the losses through the tuners, figuring that if the total loss through both of them was acceptable feeding the impedance presented by the feedline, I'd be happy with the loss through one.
I first set up the ATU to test for a 1:1 SWR on my antenna like this: RIG -> ATU1 -> ANT Then I disconnected the ATU from the antenna and substituted the second ATU "output". A 50 ohm dummy load was connected to the second ATU. So it all ended up like this: RIG -> ATU1 -> ATU2 -> DUMMY LOAD I carefully adjusted ATU2 for an SWR of 1:1 at the output of the rig again, without touching the settings on ATU1, since ATU losses can vary widely depending upon the load it is "matching". Power was measured at the output of the rig and at the dummy load connected to the second ATU to determine the total loss. It worked, but it demanded a much more accurate means of assessing the SWR than the typical SWR bridge for accurate results. With a typical SWR bridge used for matching to an antenna, I could shown a huge range of "loss" or "low loss" all while the SWR meter stayed at 1:1 - or as close as it was capable of measuring. I did get some good results only using an accurate return loss bridge that can measure SWR to a degree common meters can't approach. Perhaps an "antenna analyzer" also would provide that sort of accuracy. Ron AC7AC -----Original Message----- Great Idea - thanks for pointing me to the obvious <GR>. Just as I was contriving a highly complex solution to a non existent problem!! Besides, one could always use another balun. 73s Pete > > From: Karl Larsen <[EMAIL PROTECTED]> > Date: 2006/10/07 Sat AM 07:07:13 CDT > To: Dave G4AON <[EMAIL PROTECTED]> > CC: elecraft@mailman.qth.net > Subject: Re: [Elecraft] Baluns & wires & feeders (oh, my!) > > Dave G4AON wrote: > > There is a simple way to measure the efficiency of a balun, make two > > of them and connect them "back to back". Measure the power fed to > > them and the corresponding output power. Obviously this doesn't take > > a mismatched antenna into account. > > > I did just that about this 5 years ago. I used two MFJ tuners > connected by the 4:1 baluns in each. I fed one from my MFJ Antenna > Analyser and hooked a 50 ohm resister to the other tuner. I measured the > voltage across the resistor with a RF probe. > > Alas I can't locate the paper where I wrote down the results. Over > the bands the loss was around 10-15% I recall and I thought that was > about what I expected. > > > 73 Karl K5DI _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
