Simple Ham Radio Antennas. An 80-10 Meter Field Day Inverted Vee Antenna. Post #282


ARRL Field Day is right around the proverbial corner–28 June to 29 June 2014, to be exact.  According to the ARRL, more than 35,000 amateur radio operators used 2,500 emergency-powered stations to get on the air in 2013.   A similar number is expected this year.

While many of our fellow amateurs will be heading to a Field Day site, there are a few of us, including yours truly, who will be operating under emergency conditions at home as 1E stations or as mobile stations as 1C.  For those of us home bound or forced by HOAs or CC & Rs to “hit the road” during Field Day, this national emergency communications exercise can be just as much fun and instructive as showing up a your club site.

Before I retired from the commercial broadcast business, I usually worked Saturdays and Sundays in the news room, doing play by play over the radio, or hosting remote broadcasts from shopping malls and craft fairs.  Great work and lots of crazy people, but I often missed a chance to work 2A Pacific from the Wailoa Visitor Center in Hilo.  So, I had to join the action as a home or mobile station running emergency power from solar-charged batteries or my trusty Honda generator.

Here’s the station I used when work required me to miss operating with members of the Big Island Amateur Radio Club (Hawaii Island) on Field Day.

I wanted my emergency antenna to be simple, multi-banded (80-10 meters), easy to build and take down, and transportable in case I had to move my location.  I didn’t want to worry about an extensive ground system.  That meant no ground-mounted verticals.  The configuration I chose for my 2010 Field Day antenna was an easily built 80 meter inverted vee fed with 450 ohm ladder line.  The ladder line would be connected to a 4:1 balun.  A length of 50 ohm coaxial cable (RG-8X) would run from the balun to my trusty Drake MN-4 antenna transmatch.  Short pieces of coax would interconnect the Drake MN-4 to my Ten-Tec Argosy II, a dummy load (Heathkit Cantenna), and a low pass filter.  

Overall, the improvised inverted vee performed well with the Argosy II running slightly under 50 watts output.

According to the plans I drew up four years ago, I needed the following materials:

One telescoping fiberglass mast to support the inverted vee.  I had a spare MFJ 33-foot/10.06 meters mast in the garage.

Six, 6-foot/1.82 meters wooden garden stakes.  One would support the mast, two would be tie off points for the inverted vee elements, and three stakes would support the 450 ohm ladder line/feed line off the ground until it terminated in the 4:1 current balun on the garage wall (the shack was in an enclosed two-car garage).

Fifty-feet/15.24 meters of 450 ohm ladder line (the feed line).

One ladder lock device to support the apex of the inverted vee.

Two ceramic insulators to secure the ends of each leg of the antenna.

One 6-ft/1.82 piece of RG-8X coaxial cable with UHF connectors

One 10-foot/3.04 meters piece of RG-8X coaxial cable with UHF connectors.

One W9INN 4:1 current balun.

Nylon rope to tie off the antenna elements to their wooden support stakes.

Station equipment, including basic tools, a Ten-Tec Argosy II transceiver, Drake MN-4 antenna transmatch (tuner), a Heathkit Cantenna dummy load, and a low pass filter.

A “counterpoise bundle” consisting of a 1/4 wavelength piece of wire for 80, 40, 20, 15, and 10 meters.  The counterpoise would be attached to the ground lug of the Drake MN-4.

Sufficient lengths of #14 AWG house wire to make each element of the inverted vee.  Using the general formula for a dipole, 468/f (MHz)=L (ft), and the lowest frequency of operation, 3.775 MHz, I cut two equal lengths of wire measuring 62-feet/18.90 meters each. This length was a rounding off of the calculated lengths of 61.98-feet/18.89 meters for each antenna leg.

ASSEMBLY:

The inverted vee was built on the ground.

I attached the top of the ladder-lock center connector to the small metal ring at the top of the fiberglass mast.  Each leg of the ladder line was run through its respective hole in the ladder lock.

I attached the pre-cut lengths of antenna wire (62-ft/18.90 metes) to the ladder line and soldered the connections.  Each connection was wrapped with several layers of vinyl electrical tape.

A ceramic insulator was attached to the free end (bottom portion) of each antenna segment.

I secured the ladder line to the fiberglass mast with nylon ties and ran the line to a point 5-feet/1.52 meters above the bottom of the mast.  This would keep the feed line off the ground until it reached the 4:1 balun on the garage wall.

I carefully hoisted the mast onto its support stake.  Each sloping antenna element was tied off to a wooden support stake with nylon rope.  The antenna was adjusted for a uniform, balanced shape. with the end of the drooping elements approximately 5-feet/1.52 meters off the ground.

The ladder line was strung out from the mast and was supported off the ground by three 6-foot/1.83 meters wooden stakes.

The ladder line was terminated at the W9INN 4:1 current balun.

A 6-foot/1.82 meter length of RG-8X with UHF connectors ran from the 4:1 balun to the patch panel in the window of the radio room.  A 10-foot/3.04 meters section of RG-8X with UHF connectors ran from the patch panel to the Drake MN-4 antenna transmatch (tuner).  Small pieces of RG-8X interconnected the Argosy II, low pass filter, and Heathkit Cantenna dummy load to the Drake MN-4.

Finally, a “counterpoise bundle” was connected to the ground lug of the Drake MN-4 antenna transmatch.

RESULTS:

With the Drake MN-4 in the antenna system, I was able to get a 1.1 to 1 SWR reading on 80, 40, 20, 15, and 10 meters.  Tuning below 3.700 MHz was a bit touchy, because the antenna was designed to be resonant at 3.775 MHz.  I made 50 or so contacts during my brief appearance (5 hours) on the air.  My best contacts were made on 40 and 20 meters.  

For a quickly made antenna, the inverted vee did an acceptable job. The antennas was easily built, cheap, and performed satisfactorily. This is the antenna I carry with me in my Honda Odyssey van. I’ve used this arrangement at public parks and beach areas around Hawaii Island.  With the Argosy II or Yaesu FT-7 packed in the back of the van, all I need is my solar- charged deep cycle marine battery to get on the air.

There’s a good chance I’ll be free for this year’s edition of Field Day.  But, if I’m not, I can set up a portable station in just a few minutes.

Good luck in this special event!

Here are some additional Field Day antenna ideas:

http://www.g7fek.co.uk/software/G7FEK%20antenna.pdf.
(a multi-band “nested marconi” antenna).

http://www.hamuniverse.com/ae5jufielddayantenna.html.
(75-40-20 meter Field Day Antenna).

http://www.hamuniverse.com?kl7bobfielddayant.html.
(Field Day Antenna–5 bands with tuner).

http://www.eznec.com/Amateur/Articles/Field_Day_Special.pdf.
(Field Day Special-EZnec).  Original article published in “QST”, June, 1987, pp.21-24, by Ray Lewallen, W7EL.

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Thanks for joining us today!

Aloha de Russ (KH6JRM)

BK29jx15–along the beautiful Hamakua Coast of Hawaii Island.



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