Monday, July 27, 2009

88' EDZ antenna

The 88' EDZ (Extended Double Zepp) antenna that I made out of zip cord for the Flight of the Bumblebees worked well enough that I have added it to my portable antenna arsenal. It loaded easily using my Emtech ZM-2 antenna tuner. It was so simple to make and took all of about maybe 15 minutes.

I made mine from a 75 foot roll of 24 gauge Radio Shack speaker wire. I took the roll in the backyard and using my 100 foot tape measure, I determined where the 44 foot point was from the end of the roll. I marked this point with a very small tie wrap. The purpose of the tie wrap is to prevent the wire from splitting past the 44 foot point when you make the "legs" of the doublet. You could simply mark the wire at this point, split the legs and tie a knot with the legs at this point and achieve the same effect. I chose to do it this way, and right behind the first tie wrap, I put a second, not only as a reinforcement; but also to hold a fishing swivel which serves as a center support "hanger". The rest of the roll becomes the feedline. At the end of each leg I also tie wrapped another swivel to serve as insulator/"rope" supports. At the radio end, I bared about an inch worth of wire and tinned it with solder. This goes through the holes of the binding posts of the ZM-2 quite nicely.

Now let's face it, this antenna will be used for outdoor QRP contests; or for times when I will be operating outdoors for at least a couple of hours. Using the crappie pole as a center support; or finding at least one tree as a center support is not for those "lunch hour" sessions when time is of the essence. For times like these the Buddistick, PAC-12 or Hamsticks on the car roof are a better option. But in my mind, if you have the luxury of time on your side; then nothing beats a wire dipole/doublet up as high as you can possibly get it.

The beauty of the Zip Cord 88 as I will call it from here on, is that it is cheap, it's easy to make; and it's VERY light. And you won't have a heart attack if something should happen to it (forget it and leave it behind, etc.).

In the near future, I will try to take some pictures of the construction and will add them to the "Portable Ops" page of my Website.

73 de Larry W2LJ

3 comments:

kb4qqj said...

Hi Larry,
I use a version of that antenna on a regular basis when operating portable. You have seen the merit in it so I won't go into that. However, I will say, when I've only got an hour to play or I pull over at a nice looking spot to operate, I find it goes up faster than my buddistick and works far better. Instead of trying to hang it by the center, or suspending each end, use it as a "sloper". Throw one leg over anything (non conductive) higher than 20 feet and it will amaze you. You and I have worked a few times on that very system in the NAQCC/SKCC events. My favorite is to separate 23 feet on a leg, tie a repairman's knot, leave 50 feet together as the feedline into two banana plugs. plug those into a balanced line tuner, viola, instant contacts!! For my rigs, that combination works better on 40 and loads 30 easy too. The BLT will load it 80-10. I too use fishing swivels to tie the end of the legs off. Great little take along antenna any way you use it.

73 es BCNU
Randy _ KB4QQJ

kmacker said...

Getting ready to make one of these and see how it works! Thanks for both your comments on how you made and use them. I'm looking to lighten the load and also wonder how the 44 foot version will load on a BLT. Guess I will find out soon! 73, Kelly K4UPG http://k4upg.com is my blog

Anonymous said...

Cool story as for me. I'd like to read something more concerning this matter. The only thing this blog needs is a few pictures of some devices.
Katherine Stepman
Phone jammers