Sunday, July 8, 2012

Simple Antennas for the Amateur Radio Operator--a continuing series

KH6JRM's Amateur Radio Blog
Post 164

A QUICKLY DEPLOYED "LONG WIRE" ANTENNA

Most of my weekend chores are done, which gives me a few hours to play with antennas before Monday arrives.  Yes, even for those of us in the "semi-retired" category, there are things to do before the warm glow of vacuum tubes draws us back to the rf circus.

I've been able to build and test numerous antenna designs over the past few weeks, thanks to a break from my substitute teaching duties.  My xyl and I expect to be called shortly for another assignment since Hawaii public schools begin during the first week of August.  So, there's lots to do--clean up the "shack", inventory equipment, and otherwise try to find stuff I misplaced over the year. 

As for antennas, I decided to take down the inverted 40-meter vee for maintenance.  Rats and other small animals have chewed up some of the wire elements and a piece of coax I used to connect the 4:1 balun to the Drake MN-4 tuner.  While I was cleaning the mast and cleaning up the destruction from my little furry rodents, I noticed a 30 to 40-foot tree about 100 feet in back of the strip separating my house from the nearest neighbor.  Hmmm, I thought.  Why not string up a "long wire" from the garage roof to the tree and see what happens?  I used a similar arrangement years ago when I was a novice operator and had some good contacts.  I found several 33-foot rolls of AWG 22 gauge wire in the garage and a 40-foot length of 450-ohm ladder line from a previous experiment in the "junque" box.

I connected enough rolls of wire to make a length of 132 feet for the random wire.  I attached the wire to one lead of the ladder line, attached the other leg of the ladder line to my under-the-house 40-meter loop, and ran the assemblage to a 4:1 balun.  A short length of RG-6 coax connected the antenna to the Drake MN-4 tuner and then to the venerable Swan 100-MX.

I was able to run all bands from 80-meters through 10 meters, thanks to the ladder line and balun.  With power running between 10 and 50 watts, I was able to make plenty of daytime contacts on 20 and 15 meters by mid-afternoon.  I'll see what 80 and 40 meters does tonight.  I was able to reduce the SWR to 1.7 or better on most bands.  Nothing spectacular, of course, but contacts were made and the Drake MN-4 stayed cool.  The old Swan just chugged along without complaint. 

I will probably take the antenna down in a few days and replace it with the repaired 40 meter inverted vee.  The vee has much less visual impact than a bare wire swinging between my garage and the ohia tree.  All of this was good fun.  Besides, the project enabled me to get outside and enjoy some sun after many days of rain, gusty winds, and even thunderstorms.  Never a dull moment in the Central Pacific.

Until next time....

Aloha es 73 de KH6JRM--BK29jx15