Another use for a DirecTV antenna mount |
| It seems like a lifetime ago that I was installing direct to home sat dishes on everything that didn't move. DirecTV receiver kits were available everywhere. The antenna mounts were a great design that was useful for all kinds of lightweight antennas. While cleaning out the garage I came across a few and thought how I could use one without drilling holes in a roof. The pictures that are with this posting detail everything needed to make a bolt it anywhere dual band groundplane antenna. |
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| The antenna is nothing more than a SO-239 UHF chassis connector with cut down .075"thick steel clothes hangers for elements. The four radials are 20" long. They are bent at a tight radius and soldered into each of the four holes of the connector. Make sure they are free of any paint. I used an exacto knife to scrape the last inch clean before bending them. The S0-239 also needs to be clean and ready to accept solder. The vertical elements are 19" and 6" long. I made the lengths a little short because my use is that of a scanner antenna. The shorter element is crimped and soldered just like the radials. After everything had cooled off, I added a marine grade epoxy to the connector. The idea was to add a little support and also act as a seal. |
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| IF your application is to use the antenna for two meter FM, my suggestion is to make the elements a little longer by about a half inch. With the extra length both bands can be cut to whatever frequency center you like. I'd alternate between bands while checking the VSWR to make sure interaction is kept to a minimum. |
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The DirecTV mount comes in play as a way to hold the antenna. I bought a 1.5" PVC coupling and a 1.5" to 3/4" PVC adapter from Home Depot. With a small amount of persuasion the coupling will fit over the end of the DTV mount. Once the coupling is in place, just add the adapter. A four inch piece of 3/4" PVC pipe is what actually holds the S0-239 after the male PL-259 connector is screwed into it. Cutting slots of about an inch long 90 degrees apart, allow the PVC to grab the outside of the PL-259 after a small amount of electrical tape is added. The last piece of hardware is a hose clamp that fill fit the outside of the PVC.
If you have a concern about the coupling coming off the mount, don't sweat it. I have had this contraption at the base of my Diamond verticle antenna for almost a year with no problems.
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| The last thing to do is to bend the radials at a 45 degree angle from the mount. It's my understanding that this aids in making the antenna look more like a 50 ohm impedance. I painted the white PVC black with spray paint for plastic just to make it look a little better. I also painted the antenna itself to protect against rusting. I needed to use it for transmit and it seems that the 19" length for two meters gives a vswr of 1:1 at the low end of the band! |
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| KB2UMJ at Y A H O O dot com |
5-2014 |
