Interesting loop tests with 1:1 baluns on 160m

After reading some advice on a radioamateur forum regarding the use of a "short" loop like I have on 160m I tried a 1:1 balun between the ladderline and tuner instead of the built in 1:4 balun. I can't tune my loop on 160m unfortenately, it could be the Palstar AT1KM differential T-tuner has not enough capacity. The story goes that the R of the loop is lower as 50 Ohm and if you use a 1:4 balun R would be even 4 times less which is the cause of difficult to no tune. Another story goes that a 1:1 balun between the transceiver and the loop should supress interference, noise or whatever. Time to test the truth!

The Palstar is able to act as a endfed tuner by removing a bridge to the 1:4 balun inside. I tested it with only one end of the loop connected it didn't make much difference against my short vertical fed by coax and a autotuner at the feedpoint although the noise was 1 S-unit stronger. I use the vertical as reference for the tests I made.

I first connected a Diamond BU-50 1:1 balun to the ladderline and tuner. It immidiatly occured to me that tuning on 160m and 80m was easy but 40-10 got difficult. I then made a transmission on JT65 on 160m and was received but not with that good signals. I tuned in on some SSB stations from Italy and switched over to my vertical. The difference was astonishing, the vertical receive was at least 4 S-units better. And I was able to hear other stations that could not be heard on the loop. The balun is ok, nothing wrong with it. So this was not a great succes, the only advantage was that I could tune the loop!

Now, I don't have a lot of noise on 160m. But with the pre-amp of the Icom-706 on I can produce a S6 noise signal. Time to test the noise reducing story. This time I used a homemade balun with 50 Ohm semi rigid coax cable on a 4C65 ferrit core. You can see it on the picture. I connected it between the tuner and the radio. To keep a long story short, I cannot hear or see any difference! The noise was S6 with or without the balun. I then switched to the loop acting as a endfed and have S7 noise, again tested it with and without the balun and it did not make any difference.

What is my conclusion? Or what did I learn? Well, I can get the loop working on 160m with the tuner and a 1:1 balun but not with a 1:4 balun. Strange as others with similair loops can, though I doubt the effectivity of those antennas. My too short vertical is defenitely doing a lot better. Besides that, standard antenna theory never works here, for some reason it is always different from what others experience. I learned that when building a endfed and several other antennas. What I learned is that the advice given by others is not always working, actually I knew that already.

I have a great time in the CQ 160m SSB right now. Just worked HV0A from the Vatican with.....the loop fed as a endfed.