Wednesday, May 14, 2014

Simple Ham Radio Antennas. A field-deployable 40-10 meter inverted V antenna. Post #275.

GOING TO THE FIELD FOR FUN AND SERIOUS BUSINESS

Considering the amount of natural and human-made disasters making headlines this year, every amateur radio operator should have a "go-kit" should it be necessary to support your community in times of emergency.  Once you have this kit, practice using it so it becomes part of your support package.

A "go-kit" should be portable, easy to set up, and contain the necessary equipment to get an amateur radio station on the air for emergency service.  Your emergency kit should also contain sufficient food, water, clothing, medical supplies, and personal items to last at least three days--more days if you can squeeze more stuff in your vehicle.

So, with this in mind, I took inventory of the "back up station" I alway take with me in my Honda Odyssey van.  The station is simple and functional.  I schedule several portable operations each year to test out the equipment and my ability to operate in the field.  In fact, such impromptu operations are an excellent way of preparing for the ARRL Field Day on 28 and 29 June 2014.  There's nothing like a little practice to keep your radio skills in shape.

When I finished mowing the lawn and cutting back some of the rainforest on my new property in the Puna District of Hawaii Island, I decided to unpack the portable station from the van and set up operations in my expansive back yard.  Everything worked very well, considering what I had available.

Here's what I assembled on Saturday afternoon, 10 May 2014:

One portable inverted V antenna made from a 33-ft/10.06 meters MFJ telescoping fiberglass mast.  The antenna elements were cut for the frequency of the Hawaii Afternoon Net (7.088 MHz), which serves as a call up frequency during emergencies. Each element was cut to a length of 33.01-ft/10.06 meters.  I used #14 AWG house wire for the antenna.

Five, 5-ft/1.52 meters wooden stakes (one to support the fiberglass mast, two for tying off the antenna elements, and two to support the feed line off the ground).

Fifty-ft/15.24 meters of 450 ohm ladder line, one W9INN 4:1 balun, and 25-ft/7.62 meters of RG-8X coaxial cable with UHF fittings.  These elements would allow me to operate on amateur radio frequencies between 40 and 10 meters.

One solar-charged  deep cycle marine battery.

One Yaesu FT-7 QRP 80-10 meters transceiver.  This is an old, dependable rig I was saving for such a purpose.

One W9INN 4:1 balun.

One MFJ air-cooled dummy load.

One J-38 key and a Yaesu microphone (the one that came with the FT-7).

Two folding tables, a folding chair, a beach umbrella for sun protection, a cooler full of iced tea, and my trusty Kenwood TR-2500 2 meter HT for some local repeater contacts.

SET UP:

Once the antenna was assembled on the ground, the wooden support stakes pre-positioned, and the apex of the V antenna attached to the top of the mast with a "Ladder Lock" device, I was set to go.

I hoisted the fiberglass mast into position, adjusted the V antenna to a uniform shape, and ran the ladder line to the 4:1 balun attached to one of the two folding tables.  Twenty-five ft/7.62 meters of RG-8X was connected to the balun and run into the MFJ-941 Versa Tuner II.  Short patch cables made from RG-8X coax connected the FT-7 and dummy load to the ATU.  I also attached a multiwire "counterpoise bundle" to the ground lug of the ATU.

RESULTS:

This simple antenna gave me several hours of pleasurable operating before I had to "call it a day".  I also made a few contacts on local repeaters with the old, but serviceable Kenwood TR-2500.  Just before sunset, I repacked the portable station in a large Rubbermaid plastic storage bin.  With the second row of seats lowered, I was able to store the folding tables, folding chair, collapsed fiberglass mast, and the marine battery in the back half of the van.  All exposed items were covered by an old quilt. I still had some room left to store some water, snacks, clothing, and the umbrella.

All told, this was a productive, enjoyable day.  This also served as valuable practice for ARRL Field Day, which will be held 28/29 June.

Here are some references that may help you set up your own radio "go-kit":

http://www.emergencyradiogokit.com.

http://www.iw5edi.com/technical-articles/building-a-go-kit.

http://www.races.org/gokit.htm.

http://www.youtube.com/watch?v=gmnnf0xUWNM.

http://www.desotoarc.org/jumpkit.pdf.

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Until next time,

Aloha,

Russ (KH6JRM)

BK29jx15--along the beautiful Hamakua Coast of Hawaii Island.

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