Thursday, May 10, 2012

Simple Antennas for the Amateur Radio Operator

A few days ago, the good folks at eham.net ran a series of comments from amateur radio operators who used the MFJ 1622 portable antenna system.  The antenna consists of a tapped air coil, a 5 1/2 foot antenna, a counterpoise wire, a short length of coax, and a sturdy clamp to attach the antenna to a bench, railing, or other support.  I was gratified to see some positive reports on this compromise antenna, which, despite its faults, can get you on the air in a space-restricted environment.  The MFJ 1622 is a copy of an older design by B & K, which marketed the device in the 1970-1985 time frame.  I bought one of these when I was first licensed as a novice, used it with some success, and later stored it for emergency use.

Presently, my B & K system is located in my van, along with some coax, a spare ATU, about 100-feet of wire, a deep-cycle marine battery, and some pre-cut counterpoise wire.  My trusty Yaesu FT-7 serves as the rig.  Despite the 10 to 20 watts output of the old Yaesu FT-7, I have made many cw and SSB contacts from Hawaii Island on this antenna system.  So, while the MFJ copy has its limitations, it could be just the thing for those of you who must use stealth antennas to get on the air.  I believe the cost of the MFJ 1622 is $99.95 USD.

As for other emergency antennas, I've repaired and cleaned up an old Hustler mobile system.  The antenna in my storage space is the one with the 54-inch break over mast and coils for 40m, 20, and 15 meters.  The antenna came with a hefty bumper mount and a large spring which takes some of the abuse found in mobile operations.  I haven't found a good place to mount this antenna on my Odyssey van, so I will keep the antenna for emergency home use.  Last week, I attached the mast and coils to my metal garage roof.  The antenna seemed to work pretty well.  I've even used a mag mount with "Ham Stick" antennas for home use.  No real outstanding performance here, but this arrangement will get you on the air.  Those of you with space restrictions may want to use a mobile HF antenna mounted on your vehicle for home operation.  You can alway attach a few radials to the antenna base to improve performance.

Eventhough it's possible to run an amateur radio station with indoor antennas, I prefer to get my "skyhooks" outside.  I've used indoor antennas at qrp power levels (less than 10 watts) with some success.  However, I always seem to pick up more noise inside the house with indoor antennas.  There is also the danger of rf exposure if you run high power with indoor antennas.  If you have no other way of erecting a decent outdoor antenna, a carefully designed indoor antenna running at qrp power levels may keep you in the game.  Some of the digital modes, such as PSK 31, seem to work well at lower power levels.  The  ARRL and CQ Publications offer several books on stealth or hidden antennas that may help you keep active in deed-restricted areas.

That's all for now.  Tomorrow is another day of teaching at Laupahoehoe High and Elementary School.  Once I polish off a few lesson plans, it will be time to "hit the sack" for some sleep.  Have a good day!

Aloha es 73 de KH6JRM--BK29jx15