The QRPer Board

I saw a Youtube video yesterday from vendor night at this year's FDIM. IN it, Adam showed an antenna that has a 15 foot radiator and a 7.5 foot radial connected to a 4:1 unun that he said is perfect for the KH-1. Searching online shows that this is similar to the Rybakov 806 antenna but I couldn't find it on his website or Youtube videos.

Has anyone tried this type of antenna? My current "ultaportable" EFRW uses a 29 foot radiator and a 17 foot radial - this Rybakov-like design would work even better with my 7.2m collapsible mast (fishing pole).

Mike, KL7MJ

I built an antenna this weekend with a 4:1 unun connected to a common-mode choke, with a 20 foot radiator and a 7.5 foot radial. I couldn't get it to tune up on 40, but could on 30, 20 and 17. I tried calling CQ using a TR-35 and checking for results on RBN. I was picked up by one station on 20m - nothing on 30 or 17.

As far as tuning on 40m, my ZM-2 seems to have a problem in the 6.5MHz to 7.5MHz region. I can get an antenna (or just the tuner) to load on 80m but it is difficult to tune on 40m.

I'm going to use the unun/cmc combination to build a rybakov antenna and see how that goes.

try using a 9:1 followed by a choke, for the radiator size, use this

https://k7mem.com/Ant_End_Fed.html#Not_Random_Multi

as for the "counterpoise" a 1/16 wave wire at the lowest frequency will be a good starting point, willing to "go vertical" install the radiator as an inverted L

Adam talks about this antenna design at the 13:46 mark in this video:
https://www.youtube.com/watch?v=zlv6JYFxN9g
Other than the rybakov, I haven't seen a 4:1 for an EFRW design before.

That website looks great - lots of good information. Thanks.

73,
Mike, KL7MJ

just in case

https://wb3gck.com/2018/12/09/revisitin ... -vertical/



not a "great antenna" but it works decently and is quite easy to carry/deploy

The 4:1 has become my "go to" antenna for small portable operations when I have a tuner... Same configuration, 15' radiator and 7.5' CP. What I appreciate about my 4:1 winding is the efficiency is significantly higher than any other winding I have tested...over 99% actually with Back to Back testing. You can see here, it is quite the compact package. Not as small as the kit you can get from K6ARK (Amazon) to build though (his kit can do 9:1, 4:1 or 49:1).

Joshua,
I like your setup! Did you print the piece that holds the BNC connector? It looks very useful.

73,
Mike, KL7MJ

I can get you one. Shoot me an email.