For almost exactly 16 years, I’ve been using a 66-ft. doublet antenna that I cobbled together with left-over wire wrap wire and some twisted pair for the feedline. It’s performed great over the years, and with my new telescoping mast, it works even better because I’m able to get the center up in the air higher more easily.
I recently completed rev B of the antenna. See below.
This version uses 26-ga. Poly-STEALTH antenna wire from Davis RF that my friend, Rick, K8BMA, gave me. It’s much more rugged than the wire I was using before, and while I never had any problem with the previous wire, I just get a better feeling using the Poly-STEALTH wire.
Another improvement is the center insulator. I’m now using a 3D-printed center insulator from Crazy Ham Sales. Previously, I was using a ceramic dogbone insulator as the center insulator. The twisted-pair feedline hung off the insulator with little or no strain relief. Again, I never had any problem with this arrangement, but it was kind of kludgey.
This center insulator provides strain relief for both antenna elements and the feedline. The model I purchased was designed for 300 Ω twinlead, but it does a decent job with the twisted pair wire that I use. I have a friend here in Ann Arbor who’s a big 3D printer, and I’ve got him working on a version of this center insulator that’s designed specifically for a twisted-pair feedline.
I used this antenna Tuesday on my last POTA activation and got good results. Of course, the bands were in pretty good shape Tuesday morning. Anyway, listen for me. I hope to get a bunch more POTA activations before it starts snowing. If you work me, chances are I’ll be using this antenna.
Les, KB0MEF says
I like your continued interest in making an antenna. I live in a valley at 8300 ft with 10,000 plus mountains west, north and east. I usually can only get a signal from the south. But I notice the new radios do not penitrate the atmosphere like the older models did.
John - KF6EFG says
Can you go into more detail about the ‘twisted wire’ feedline? How many turns per foot? What is the length?
Dan KB6NU says
It’s about 10-12 twists/foot and about 35 ft. long. I don’t think that either really makes that much difference, though, if you have a good antenna tuner.
Larry Wild says
Is twisted-pair commercially available, or did you manufacture your own?
Larry
KE0BTV
Dan KB6NU says
It’s commercially available. You can get it at Jameco or any other electronics distributor.