Thanks Dave, I always appreciate your tips and insight. This is a topic I felt I knew already and yet I still learned more about it that I didn't know. Great explanation!
I use a 107 ft non-resonant wire up about 25 feet with a 9:1 unun and a 120+ ft insulated counterpoise running off the unun at about 90 degrees and then down a steep slope and curving around at the bottom of the 50 ft hill, mostly a few feet above the ground on the wooden staircase handrail and bushes. I use a choke right under the unun and another right before the lightening arrestor to discourage rf on the shield of the coax. This tunes all bands 160m through 6 meters with good results in actual use. The key to tuning on 80 and 160 meters was the very long counterpoise (80 feet did not work well). Makes jumping bands super easy. Definitely a compromise antenna, but gets me on the air with fun qso's on every band! 73, N7RLV
thanks for really interesting information on counterpoise for long wire antenna David! I have a spacy backyard for 148 ft wire with 9:1 But I can't have long coax so I need a conuterpoise. What counterpoise length will go with 148 ft antenna wire?
Just found your series of videos, very informative. I will be attempting to build a random length antenna. As follows: 15' coax from my radio to a lightening protection device outside the house, connected to a ground rod, then a 1:1 unun, then about 45' of coax to a 9:1 unun, connected to 148' of antenna wire ran in trees in my back yard. Do you feel the 45' of coax grounded at the lightning protector will be sufficient as a counterpoise? Am I missing something in my plans? I have sketches if you have a place for me to send them!!
Dave, or anyone that may know. relativly new to ham, and after a year I decided to setup my first station. I went to a ham store that opened about 3 years ago, I do not know enough to trust / know if he is right or BS. He is trying to sell me a 40 foot free-standing tower, I feel I need the tower for my location, however I want a vertical antenn and no guides, he said a BTV5 and the tower will work as the counterpoise/ grouding radials. Hmm. I can not have any wires guiding the tower hence free-standing tower, nor can I have wires running off the antenna. Is he right? will the tower act as the counterpoise?
I always am astounded by the "how long is a good long wire?" argument. May as well say 10M in a Rybakov configuration with loads of radials. Mind you Chameleon antenna uses 20M of wire so it is debatable as to the length itself. Whenever people ask me about an antenna I just say look up Rybakov and make that for the yard. It is a 4:1 balun and you get to have a small vertical to play with to get you on the air. If thy mention long wire, speaker cable will do it. It's cheap and 10M long. Split it in the middle and you get 20M for a cheap antenna and a sort of dipole as well for 14MHz.
When you are using Coax as your counterpoise in your End Fed Long Wire system, can you bury the wire below ground and/or run it through a small conduit without rendering the counterpoise/ground coupling effect useless?
Thank you! I am going to put my antenna on a 5 foot standoff from my tower, about 50 feet up running from there to the back of my yard. Run the coax down to my ground/surge protector. That is what you said.
I have a PAR EF 80-10 JR deployed as a slant from the roof to a 4 section military pole on corner lot (@ 25 feet). My SWR went bonkers out of the blue and I was struggling to determine the issue. I looked at the handout for the antenna and it recommended the isolator as one option. I did this and my SWR on 80 and 40 were still high. I noticed that the coax length was important and needed to be at least 1/4 wavelength. As I added coax sections the SWR started dropping. Long story short, I ended up with around 60 feet of coax and that did the trick. 80 Meters is 1.9 to 1, best I get right now. When the winds die down I will get back out there and finish up. Steve VA3FLF
Thanks again OG for this video. I believe that I will acquire the MFJ 915, because like my long wire (connected directly from the roof of my chimney to a distant tree of approximately 16m with a UNUN of 9:1 on the chimney then my coaxial descent of 10m) I think that I would no longer have HF feedback (it stings lol) on my Kenwood 450 SAT. Besides, with my ICOM 7300 or YAESU FT991A, I don't have this problem. Best 73's/Joel/F8MGW
You are correct. IF necessary, there are basically two solutions to mitigate common mode currents with long or random wire antennas. One is to use a counter poise and two is to insert a common mode choke in the coax at roughly 20' or 7 meters away from the antenna feedpoint. In the second case, the 20' of coax will act as a counter poise.
