Saturday, July 25, 2020

Revamping the Endfed antenna

The new location for Endfed....Shingles are my next project
When we moved into our place last August I set up my Endfed as a temp setup and as with most things temp soon becomes long term. My excuse was I just had major house "things" on the go that required my attention. Over the winter the temporary support at one end of the Endfed was starting to show some major wear. I decided to stick with an Endfed antenna as with my lot size it was the best option for me.
The new spot for the antenna
 I was doing some reading on the internet regarding Endfed antennas and the ideal wire lengths. For the size of my lot, the length that was ideal for me was 41 feet. My plan was to remove the balun from the tree it was located in and mount it on my newly renovated in the pictures the shingles have not been done yet but that is my next project and the shed will be complete. The 41-foot Endfed antenna wire would extend back out to the tree. I guess you could say I just reversed the setup. This setup allowed me to lower the balun to about 6 feet off the ground and have the antenna slope in an upward direction. This setup would allow me to add a counterpoise to the Endfed. When the Balun was located in the tree it was about 25 feet off the ground and I was advised by Ultimax antenna the balun was too high off the ground for a counterpoise to work, I did try it without success. 
Splice making 34 to 41 feet
I first tried the antenna with the counterpoise and was not pleased with the results I removed the counterpoise and gained some better results on some bands. Below are the results with and without the counterpoise. 
Results without a counterpoise:
       Band Freq SWR
    80. 4.000. 7.5
    80. 3.500. 6.7
    40. 7.001. 3.2
    40. 7.070. 3.3
    30. 10.100. 5.0
    30. 10.150. 5.0
    20. 14.001. 1.8
    20. 14.070. 1.7
    17. 18.068. 1.6
    17. 18.168. 1.6
    21. 21.001. 2.6
    21. 21.070. 2.6

Results with a counterpoise:
         Band Freq SWR
    80. 4.000. 9.1
    80. 3.500. 9.6
    40. 7.001. 4.4
    40. 7.070. 4.4
    30. 10.100. 5.0
    30. 10.150. 5.0
    20. 14.001. 2.4
    20. 14.070. 2.3
    17. 18.068. 2.0
    17. 18.168. 2.0
    21. 21.001. 2.6
    21. 21.070. 2.7
Below is the SWR reading when the Endfed was 34 feet long and located with the Balun in the tree. 

Results without a counterpoise:
Band Freq SWR
    80. 4.000. 7.0
    80. 3.500. 8.1
    40. 7.001. 1.8
    40. 7.070. 1.8
    30. 10.100. 3.3
    30. 10.150. 3.3
    20. 14.001. 4.6
    20. 14.070. 4.6
    17. 18.068. 2.5
    17. 18.168. 2.5
    21. 21.001. 1.5
    21. 21.070. 1.5

Results with a counterpoise and the balun 25 feet in the tree:
Band Freq SWR
    80. 4.000. 6.5
    80. 3.500. 9.1
    40. 7.001. 5.2
    40. 7.070. 5.2
    30. 10.100. 2.2
    30. 10.150. 2.2
    20. 14.001. 4.9
    20. 14.070. 4.9
    17. 18.068. 2.7
    17. 18.168. 2.6
    21. 21.001. 1.6
    21. 21.070. 1.5


VA3ZC said...

Hi Mike,
Interesting results. Looks like 41' without a counterpoise is best. Are you getting any rf in the shack without the counterpoise? The coax is the other half of the antenna in that case. You can choke it before entering the shack but that length of counterpoise is important as well.

Is that the Ultimax 100? How long is your counterpoise. It's length will affect swr.

I've been looking at 49:1 baluns. The conventional wisdom is to mount the balun just above ground and use a 6' ground stake instead of a counterpoise. Not sure if that would apply to your balun.

I think that 41' might be too short for 80m. Ideally you should be able to get 2 bands under 2:1 without a tuner (multiples, say 40 and 20) and then some of the remaining bands with a built in tuner. Finally an external wide range tuner for any other bands though efficiency might be low.

I've used a 9:1 balun (random wire ef) and an external tuner with good dx results so they do work well especially in small spaces.

Good luck with your experiments.
Paul VA3ZC

VE9KK said...

Good Sunday afternoon Paul and very nice to hear from you, It would seem that 41 feet without the counterpoise is the way to go BUT I have been reading online about 44 feet and I may try that out with and without a counterpoise to see how that works out. As for RF, I have Balun designs 1:1 balun as the coax enters the shack and that has taken care of most of the RF issues. I have always had issues with 40m when I am above 60 watts. I have not tried above that power with the new antenna length as of yet.

The counterpoise was purchase separately from Ultimax I believe it's about 20 to 25 feet long.

It's tough out this way to mount the balun at or close to ground level as we get a large amount of snow in the winter. I do have a ground rod close by and I could run a wire to that and see if that makes any difference.

As for a tuner I use the LDG AT-200Pro II tuner and it has no issues getting me a decent SWR on all bands with the Endfed.

I have been doing great with the Endfed from here and I am very happy to get on the air and get DX with the small space that I have here.

73 Paul and thanks for stopping by and leaving a comment.

VA3ZC said...

Hi Mike,
Sounds like you are pretty much set up then.

Just to clarify, if you have the 1:1 choke then you don't need the counterpoise since the shield of the coax preforms that task. Your "counterpoise" then is the length of coax from feedpoint to choke. Adding a second counterpoise might be counterproductive.

If you are having problems on 40m you could add a counterpoise to the back of the radio and run it along a baseboard. Just make sure to tape up any exposed ends.

I guess your balun is 4:1 and the wire is a random length that avoids resonance on bands that you want to work? That is similar to the 9:1 design.

The 49:1 is a different animal. The wire is cut to a resonant frequency. Eg.A 1/2 wave on 40m and then will also work on 20. Both bands without a tuner and very efficient. Add a tuner for the remaining bands but with reduced efficiency.

Good luck!
Paul VA3ZC

VE9KK said...

Good evening again Paul, I do for the most part have things setup I am at the point now of tweaking it. I sometimes find that it's the "tweaking" that sometime screws things up, so I am only going to try some very minor things that allow me to get back to the same old same old.

Yes I do have 1:1 balun it is installed where the coax comes into the shack from outside. I just figured that once the counterpoise was connected the coax was no longer seen as the counterpoise.

As for 40m it's not a big issue as the tuner can look after the SWR and I am able to get DX work DX with CW or FT8.

As for the Ultimax balun I thought it was a 9:1 and I have tried several times to contact them just to make sure, but they have never gotten back to me.

Thanks again for getting back to me with some feedback have a great upcoming week.