In Which We Upgrade An Antenna

As I’m sure you all know and undoubtedly agree, the bigger the antenna the better it works. This is true of wide-band receive aerials, anyway, at least up to full wavelength or so (I think – my antenna theory is a little rusty these days). Most people don’t like ten-foot antennae on their car, though, so most AM/FM receive antennas are quite a bit shorter. I, however, being a fan of good radio reception and also of big antennae, decided it was time to upgrade the car again.

When I first got the car I replaced the stupid little foot-long rubber-ducky antenna (not good reception, especially with the rusty mounting stud) with the more respectable telescoping whip from my old car. This worked pretty well, unlike the ducky, which did not really. It still didn’t seem to work as well as it had with the old radio, though. So after living with it for over a year I decided to pull out the VHF whip that I picked up from the middle of the road in Westbrook a couple years ago and see if it would improve my radio listening experience.

Converting the VHF antenna primarily involved:

  1. Finding a bolt to screw whip base on to (5/16-24 in this case)
  2. Making blocks to clamp/mount to the car
  3. Connecting it to the antenna cable in the trunk

The bolt was easy, I took the base to Fastenal and the guy figured it out. Since I only needed one (which probably cost all of about twelve cents) he was cool and just gave it to me.

Making the mounting blocks was harder because I didn’t want to use wood for longevity and wear reasons, as well as aesthetics. (Not that the end result is any better.) I ended using a plastic scrap punch-out I got from a friend. It might be HDPE, but I’m not sure. It’s hard and slippery, which makes cutting it a trick. A course-tooth wood saw seems to work well; I made the straight cuts with a sabre saw and did the diagonal with my cross-cut saw.

After trimming up edges and drilling a hole through both pieces, test mounting worked perfectly the first time. (When does that ever happen?) It holds quite securely and is the right angle and everything. I used a piece of craft foam for a gasket between the car body and top block, and the O-ring from the old loading coil to keep rain from getting down the bolt-hole.

Wiring the antenna turned out to be very easy once I got past my brain cramp about the special antenna connector. Turns out that connector is about the right size to fit a banana plug, so I plugged a test lead in there and clipped the alligator-clip end to the lug I made from a piece of computer case (5-1/4″ drive bay punchout). Eventually I’ll solder a shorter lead and banana plug on to, but for now it works. I get much better AM reception – before I had mostly engine electrical noise – and weaker FM stations seem to have improved slightly in limited in-driveway testing. We’ll see how much difference it makes in that dead spot on the interstate down near mile 43.

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