Thursday, August 11, 2011

Simple antennas for the Hawaii Amateur, part 8

Homebrew antennas are an endless source of experiment, creativity, and occasional frustration.  Armed with a few good antenna books from the ARRL,CQ Publications, and the RSGB, I've built a variety of  verticals, dipoles, and loops which work most of the time.  Since I'm not an electronics wizard, there have been a few ideas that just didn't pan out, including a homebrew 1/2 end-fed hertz that developed a bad case of corona discharge at the end of the antenna.  That 40-meter project was a disaster, but it taught a few valuable lessons about matching devices, baluns, and swr.  I think the next time I want to use an end-fed hertz, I'll violate my long-standing rule of "rolling my own" in favor of a commercial product by Par Electronics, Radiowavz, or Comet.  I'm alright when it comes to simple verticals, dipoles, and loops.  Anything beyond that calls for more study and careful attention to detail.  I'm still in the learning process--something that will continue for awhile.  The longer I live on this blue orb, the more I'm convinced that I know less and less about more and more.  I'm an analogue freak in a digital world.  Thankfully, my news assignment in a fully digitalized and modern broadcast station (AM and FM) gives me the opportunity to stay current and hopefully out of trouble.  The mere fact that I have all the coordination of a loose bicycle chain gives me pause when I attempt to embark on another antenna project.

If you don't prefer my cut and trim approach to antenna desing, you may want to try a few of the commercially marketed end fed verticals offered by Par, Radiowavz, and Comet.  I was intrigued  by some reviews on the eham.net site concerning the Comet CHA 250B, a broadband vertical covering 80-10 meters.  Like all compromise antennas, there are limitations that must be considered.  But, from what I gather from the reviews this antenna may be ideal for those with severe space limitations and restrictive CC&Rs.  The antenna seems to do well if it is mounted 36 to 40 feet off the ground. There was one amateur that used a DX Engineering swivel mount to keep the antenna hidden and protected when it was not in use.  This arrangement could get you on the air when all else fails.  Other than the price ($469). the CHA 250B seems to be a useful alternative to not operating at all.  In the past, I've use an old Hustler mast, mobile mount, and 40-meter loading coil/whip to get on the air.  Clip on a few 33-foot radials and you're in business.  Some of my fellow amateurs have also adapted the Tarheel mobile antenna for home use.  Whatever works.  Use your creativity and get on the air.  Your mileage may differ.  I've loads of fun with the simple verticals, loops, and dipoles I call my antenna "farm".   One never knows what will happen when rf leaves your skyhook and heads to the F layer...Southern Sudan, San Marino, or even Hawaii perhaps?

Have a good weekend.  Aloha es 73 de KH6JRM