ARRL

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Antenna Go-kits

08/20/2008

Ah Field Day 2007, the Cleveland (Tennessee) Amateur Radio Club set up in the beautiful and historic Red Clay State Park, the last meeting place of the Cherokee Nation before they were forced to go west on the Trail of Tears. This park is located in Tennessee just above the Georgia boundary. We were allowed to use the replica of the original meeting building, which is an open sided shed and an ideal Field Day location.

There was the usual Field Day commotion. One of our members, Jack, WA5CHJ, was using a black powder pistol with a wooden rod for a bullet to launch a monofilament fishing line across an upper limb of one of the trees. It was different! The club now has a sling shot to use that is a bit safer and much quieter. Another group was putting up a 10 meter Yagi.

The wire antennas had been thrown together into a cardboard box and were badly intertwined. I spent an hour and a half separating just some of them. Also, they were in a generally poor condition. One was made from unsuitable magnet wire while others had been spliced by just twisting the weathered wire together. Only one was marked for its band. We had to use an MFJ analyzer to determine the resonant frequency of another, only to discover it was not on a ham band. Clearly there must be a better way.

Antennas to Go

QST has published many articles on Go-kits, describing a fast way to take your personal items, self-contained rigs and batteries out to an emergency. Why not one for just an antenna?

At the next club meeting I suggested that the club assemble an antenna kit for each of the lower bands. Ignoring the advice my father gave me many years ago, I volunteered to do this for the club.

Each antenna kit should contain an antenna for a particular band with coax and support rope, all in a marked container. The antenna should be the tried, true and simple dipole. Although we have included a G5RV, which has some gain on 20 meters and above, it requires an antenna tuner.

Our dipoles were made using the formula: total length in feet = 468 divided by the frequency in megahertz. I cut the antennas longer than the design length so that they can be fine-tuned before use. The G5RV is 102 feet overall connected in the middle with 34 feet of 450 ohm open wire and then an SO-239 connector at the feed point.

Coax can be of any type: RG-58, RG-8, RG-8X or even 75 ohm RG-59 or RG-11. Any of these will work as long as it can handle the typical rig's 100 W. Use what you have or can get a member to donate. Put PL-259 connectors and the proper adapters on each end. Lengths should be either 50 or 75 feet long. Due to loses, the shorter the better.

If you decide to do this for your group, start by making an inventory of what antennas, coax and rope you have and request donations from your members. Two of our members donated extra antennas they had, while another gave us a length of coax. Record each antenna and its condition. Measure it with a yardstick to determine the band it is resonant on. In our collection we found we had two antennas for the same band.

Use an ohmmeter to check for continuity and any shorts in the center insulator or balun. If you have to buy any new wire, plastic coated, copper plated, stranded wire is probably the best choice, followed by 7-stranded copper wire and single strand Copperweld. Likewise, check the coax for opens and shorts and the use of proper reducers on the PL-259. We found a length of RG-8X that had not used adapters at all, making for a mechanically weak joint, which was also susceptible to moisture damage.

Each antenna should have a support hook on the center insulator, to allow it to be mounted as an inverted V and an SO-239 connector at the feed point. Each should have a tag with the band marked on it. Likewise, both ends of each length of coax should have a tag giving its length, type and band. This is important when someone other than the person who erected the antenna is connecting it to a rig. Might save a set of finals, too. Include a double female adapter with each length of coax so they can be joined together.

Kits Need a Case

Put out a request to your members for cases to house the kits. The ideal case is one made of plastic, such as the kind power tools come in. These are usually discarded when the tool is put in a shop. Most of your members will have one in a closet that his or her spouse will be glad to get rid of. If you can't get enough donations, visit thrift shops, yard sales and even hamfests for them. I found several for 50 cents to a dollar each. The best size for 75 and 40 meters is just a little larger and thicker than a brief case. The case that was used for older VCRs is a good choice too. For 20 meters and up, a brief case size is fine.

You will have to use a utility knife to remove some of the plastic that was used to hold the tools to allow the antenna components to fit. Do not remove more than necessary, for the doubling of the plastic in strategic areas gives the box more strength. This is the dangerous part of this project -- be careful! Mark the case with your club's name and the band it is for.

The case should have working latches and a handle. Remember -- no matter how heavy it is, if it has a handle, it is portable! Plastic is preferred as it will shed water better. Although it doesn't rain on every Field Day -- just most.

If space in the case is tight, roll the wire of the antenna, coax and rope in different diameters so that they will nest together. Also include a packing sheet telling what is in the kit. The insert sheet is a good place to record the finished frequency and SWR.

Include in each kit three 3-foot lengths of yellow plastic warning tape to put on the support ropes. You can get it at any paint or big box store. As Phil Silvers said in "It's a Mad, Mad, Mad, Mad World," "We don't want anyone tripping over it in the dark."

The G5RV was made from remnants of other antennas that had to be spliced together. There is nothing wrong with this as it ties in with an old superstition that any antenna will work well if it contains part of an older working antenna. I had to use the 7-strand bare copper that was very weathered.

To clean it up and make it solderable I used a kink that I saw in an old issue of Ham Radio. The two pieces of wire are tied in a knot; either a square or granny will work. Leave about an inch of wire on the free ends. Crimp the knot down flat. Heat the ends of the wire with a propane torch until it is red hot. Dip the heated ends into a cup of rubbing alcohol. The cleaned end will have a reddish look and will take solder very well. The knot is necessary as heating the wire weakens it. The knot will give it strength, while soldering the cleaned joint will insure good continuity. After you have soldered the ends, crimp the wire onto the knot and put electrical tape over it. This will minimize the snagging of the joint when the antenna is coiled or pulled.

We made up five kits for 80-10 meters, plus an extra one for the G5RV. Two others hold extra coax and rope. Each case should have two or three lengths of rope. Most rope now is made of plastic so use a flame to melt the ends to keep them from unraveling. To augment the rope I included twine of the type a carpenter uses. While it is cotton, it is strong enough for most antennas and will only be used out in the elements for a few days a year so it should last a long time. I used the yellow colored variety that will help warn people to avoid it.

When erecting antennas get one of the newcomers to help so he or she will better understand antenna theory. Answer any questions. So many new hams come into our ranks with a very limited, and sometimes distorted, knowledge of antennas. Be an Elmer.

Packing Up

When the contest is over, each antenna and coax set should be properly stored away in its case. Check that each item is in the antenna kit. If wet, it should be taken to a member's home to be hung out to dry in a garage or carport. Storage should be done carefully as it will make the next contest or outing easier. In our club this is the responsibility of the vice president.

If there is anything missing from one of the antenna kits, make a note of it and bring it to the attention of the group. Likewise if some item should be added, do so. Don't think of the kit as a finished item but rather as a project under construction.

Antenna-wise our club is now prepared for future Field Days, but even better we will be prepared for an emergency when it occurs. For some 70 plus years, the ARRL has been promoting Field Day as practice going out into the field, erecting antennas and operating under emergency conditions. These Go-kits will be very useful should a local or national disaster occur. By having the complete antennas ready to go in a Go-kit, we will be able to get on the air much more quickly for the next contest or emergency.

Larry G. Ledford, KA4J, has been licensed since 1962, having previously held the calls: WN4HPE and WA4YFL. His interest in Amateur Radio began in 1960 when he checked out a 1959 Handbook at the library. He has been hooked ever since. Larry likes building gear and collecting/repairing older rigs that he lusted after in his youth and can now find at affordable prices. He likes to build simple test gear and jigs. He is also into ATV and uses an old 10 foot dish on 440 MHz. He is active in the USAF Military Affiliated Radio Service (MARS) program, two local radio clubs and is a life member of the ARRL. Larry is a retired house painter who also worked for several years as a broadcast engineer. He has been married to Barbara for 25 years and has two kids and five grandchildren.

Larry G. Ledford, KA4J



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