To unun or not to unun? That is the question
2019-08-23 Yesterday I posted a thing in a Facebook group about my 29ft antenna with a QRPGuys balun and a good contact I made with it.
"I like making portable wire antennas. The end fed half wave is clearly a favorite. But non resonant end fed's also have their place. Today l put up my 29ft one as a sloper with a 17 ft counterpoise. About 45deg angle. It had a 9:1 UNUN at the feedpoint. Had two 20m SSB QSOs running 20w. But one station said I had RF on my audio. It cleared up when I switched to the EFHW. Is that a common experience?"
A guy responded with a question something like, "Why does everyone use a 9:1 balun and coax with their random wire antennas. Why don't they just connect them directly to their tuner or radio?"
Several people responded with a number of reasons. But the main one for me is that using a unun with coax into the shack allows me to place the antenna some distance from the rig, like outdoors with my rig inside.
But the question got me thinking so I decided to try my 29ft with 17ft counterpoise connected directly to my G90. The photos below show the direct connect setup as well as the setup using my QRPGuys mini-unun with ten foot coax going into the shack.
I disconnected both the 29' radiator and 17' counterpoise from the unun and connected them directly to my xiegu g90 sitting on a table in the back yard. The g90 tuned it perfectly on 40m. On 20 meters I got an SWR of less than 1.5:1 at the lower end and 2:1 upper. Didn't check other bands. With it in that configuration I had a solid 20 min CW QSO with KB3NSK on 7.053mhz. 451 miles. I was running 20 watts and he 50 watts.
I then Connected the 9:1 mini-unun again. 40m looked the same as when connected directly. But 20m had an SWR of about a 1.3:1 across the entire band.
My conclusion is that both approaches are good ones and work about the same. So I plan to use the one that best fits the situation.