October 20, 2012
6 Meter Rigid Dipole
Some years ago, I laid my hands on an old 49 MHz cordless telephone "extender" antenna. The kit acutally included two fiberglass whips 55 inches long along with some coax, mounting hardware, and some additional components necessary for retro-fitting the unit to a cordless telephone base. When I came across it I thought that it may be possible to use as a 6 meter antenna. Fast forward about 10 years, I still had the thing in storage and decided that it was finally time to give it a try.
The two identical antenna elements that came included with the range extender are intended to be used with the included mounting bracket in a vertical dipole configuration. They have the standard 3/8-24 threaded base. Also included was an antenna mounting stud with an SO-239 connector just like those used for mounting mobile antennas. I had another stud like it (minus the SO-239) and went to a local building supply store to find some additional hardware to put the antenna into service.
I used a pair of 3/8-24 hex bolts one inch long to mount the two threaded couplers (one from the antenna kit, and the other that I had in my junk box) to a 3/4 inch PVC conduit body. The conduit body, I thought, would be a perfect center insulator. It has holes in it to be attached to a piece of PVC conduit to get the thing up in the air for testing and is actually quite inexpensive. It also has plenty of room inside to add a toroid as a balun if it turns out to be necessary. Finally, it has a nice rubber gasket on the cover to help seal out the elements.
The feedline is connected to a chassis mount style SO-239 connector mounted to the back of the conduit body via an extra hole I drilled. Some 24 AWG insulated wire is then connected to the antenna mounting studs using some crimp-on ring terminals (which I soldered as well for good measure). Finally, I capped off one of the conduit holes as it will not be used. The "back" conduit hole will be used to attach a length of PVC conduit to use as a mast.
The antenna is now assembled and clamped to a chair in my garage. Of course the next step is to get the antenna outside and up in the air to perform some measurements. That will be a task for another day.
