tales of new station construction at KT8K - episode 3: 2nd Antenna (Fan Dipole)

Oct. 31, 2007
I was fired up again last night, with one antenna up, and ready to get into the next. I dug out a 500' roll of black 14 gauge THNN hookup wire and got busy.

Out in the driveway I pulled out two 67.5 foot lengths of the hookup wire. I got my soldering iron heating up in the garage, and used the point to make two holes each in three toothbrushes saved for the purpose - they make pretty good antenna insulators (and the birdies can brush their teeth while perched on the antenna).

I fed one end of each of the wire lengths through a hole in a toothbrush I would use at the feedpoint, then cut a 5" piece of the 14 ga. wire and used it to secure the element-wire by twisting it around the wire on both sides of the toothbrush (the hookup wire is solid, not stranded). Finally I tack-soldered one end of each 5" piece to each antenna wire to keep it all in place. Then I pulled the other ends of the element-wires through the other toothbrushes and twisted them back on themselves to secure them.

Then I spun about 100' of RG-58 off a spool and laid it out in the driveway. I stripped one end, separated the shield and center conductor, and soldered them to the wire ends at the center insulator-toothbrush ... feedpoint complete! Then I installed a PL-259 with adapter on the other end of the coax (checking frequently for shorts with an Ohmmeter) and, once all had cooled, sealed up the feedpoint with a good flexible, weatherproof caulk to make it water tight as possible.

Next I need to get this puppy up in the air and see how it tunes on 80m. Once it is properly pruned for 80m I will cut a couple of 33' lengths of the same wire and add 40m elements to the dipole, and, once they are tuned, will repeat the effort with 20m wires. I expect to fan the 40m and 80m elements at 90 degrees to each other, once installed, but will probably make spacers from thin PVC pipe or some cut-up plastic coathangers to suspend the 20m elements from the 40m or 80m elements. After all, I don't want the back yard to look TOO much like a giant spiderweb (my wife HATES spiders ...)

Tonight .. possibly I will be able to get ropes with pulleys in position high in the trees to support the dipole ends ... wish me luck. I want to be VERY ready for the CW Sweepstakes this coming weekend!
73 de kt8k - Tim

Submitted by kt8k on Tue, 10/31/2006 - 20:06. kt8k's blog | login or register to post comments