Thursday, September 22, 2011

The CJU Antenna

September 2011

Tired of pulling the Arrow out every time you work a pass?  Tired of being afraid to work a grid while portable because of how long it takes to assemble the Arrow?  Tired of getting all the funny looks when you DO pull it out in public?  The answer is simple... build a CJU antenna!  Build a CJU for the 440 downlink and use the 1/4 wave for the uplink on the roof of your car.  All you need to do is pull over, roll your window down, and work the pass!  I just built one recently, and I was astounded with the results.  Now, it is important to mention that I was using a preamp, but even with the preamp on the Arrow, I would have to say that the CJU performed just as well, if not better, than the Arrow - and it is only about 9-10" long! 

EA4CYQ provides some very good instructions on his webpage, so I will not go into a bunch of detail.  He uses mm, so you can take mm / 25.4 to get inches.  If you have a measuring tape with millimeters on it that is even better.

Instead of clamping my BNC connector RIGHT at the bottom of the PVC, I let the coax run out about a foot, and used hot glue (or any glue) instead of the screw clamps to hold the elements in place.  I also used silicon-copper welding rods instead of whatever he used.  In other words, I did the "built in 30 minutes" version.

A couple pics...

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