Texas ARDF: Amateur Radio Direction Finding
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What You Need to Get Started in ARDF

You do not need a lot of expensive gear to compete in Amateur Radio Direction Finding (ARDF) competitions! Compared to many hobbies (including most other activities in Amateur Radio) the cost of the simple handheld radio direction finding equipment you need to participate can be quite reasonable. In fact, if you already own an HT for 144 MHz, you have most of what you need already to get started on two meters!

Gear for 144 MHz Competitions

Two Meter Yagi
A WB2HOL design two meter yagi and a VK3YNG design two meter ARDF receiver.

For two meter ARDF competitions, there are three general options for equipment: an all-in-one ARDF receiver imported from eastern Europe, a separate yagi antenna and ARDF receiver, or a separate yagi antenna, offset attenuator, and HT or handheld scanner. European ARDF sets are not especially easy to find in North America, generally only cover 144-146 MHz, and typically only receive AM and CW. Most newcomers to the sport in North America will start with a separate antenna and receiver or receiver/attenuator combination.

A majority of the active ARDF competitors in North America use three-element yagis made from steel tape and PVC tubing. You won't be able to buy these from a ham radio store, but they are easy to build from parts you can buy at any hardware store and your local Radio Shack. Some very easy-to-follow instructions to build one of these antennas are available online thanks to Joe Leggio WB2HOL. Not only are these yagis inexpensive to build, the flexible steel tape holds up to significant abuse in the trees and bushes. You can easily build a single yagi for under $20 in parts, or for less if you build more than one at a time.

Two meter attenuator
A K0OV design two meter offset attenuator, assembled inside a PVC enclosure built into the boom of a tape measure yagi.

There are a few specialty receivers designed specifically for ARDF on two meters that are available on the market today. By far the most popular in North America right now is the VK3YNG Foxhunt Sniffer Mk4, sold by Bryan Ackerley VK3YNG, of Melbourne, Australia. This receiver includes auto-ranging attenuation and an audio S-meter. Over half of the competitors at recent USA ARDF championships have been using this receiver. Bryan has been able to keep the price under $200 USD per unit to avoid customs duty for his U.S. customer base, and he can accept payment in a variety of ways.

Another option for those who already have 144 MHz HTs or handheld scanners is to use an external offset attenuator. An offset attenuator typically provides up to 100 dB of continuously variable attenuation. The more you need to attenuate the signal to keep it at a reasonable audio level, the closer the transmitter might be. The VK3YNG receiver described above does this automatically - with an offset attenuator, you need to pay attention to the manual setting. The two easiest sources for offset attenuators are the Arrow Antennas OFHA which comes built and tested for $59, or you can buy a partial kit from Marvin Johnson KE6HTS for $15 and build it into your own enclosure. Some have even built the offset attenuator into the PVC boom of their tape measure yagi!

If you already have an HT or handheld scanner, you can build a simple three-element two meter yagi and an offset attenuator for under $50. If you get excited about ARDF, an additional investment in a specialty ARDF receiver is still less than most mobile ham radio rigs.

Gear for 3.5 MHz Competitions

For eighty meter ARDF competitions, almost everyone uses radios with the receiver and antenna integrated into a single unit. The main difference is whether the antenna is a magnetic loop design or a ferrite rod design. Ferrite rod designs can be physically smaller and lighter weight, but may not have the same sharpness in antenna pattern. Most competitors at recent North American ARDF competitions have been using magnetic loop design rigs, but mostly it is a matter of personal preference.

WB6BYU Receiver
A WB6BYU design eighty meter receiver, built by Jerry Boyd WB8WFK before the kits were available.

Many eighty meter ARDF rigs used in North America today are European models that have been imported by individuals. The Altai 3,5 and others like it from Russia, the Ukraine, or the Czech Republic have been used in eastern Europe for decades. There is, however, no reliable source for these receivers in North America, so if you really want one, you might have to find some member of Team USA going to a World Championships who might be willing to shop around on your behalf and bring one back for you. Depending on the popularity of the model and the prevailing currency exchange rate, you could spend $100 to $150, headphones included.

Probably the best option for buying an eighty meter ARDF receiver in North America is the WB6BYU design receiver being sold both as a kit or assembled/tested by Marvin Johnson KE6HTS. The WB6BYU receiver is a magnetic loop design, and details on its construction were published in the September, 2005 issue of QST magazine. Several WB6BYU receivers have been used by USA ARDF champions. Assembled and tested, the receiver is under $100 - a complete kit is $60.

If a ferrite rod antenna design is more to your liking, there are offerings from overseas, including a kit from Bryan Ackerley VK3YNG and several models available for sale from Jiri Marecek OK2BWN (email him for current prices.)

Clothing

Runners
You don't need fancy clothing to compete in ARDF!

ARDF is an outdoor sport that includes cross-country navigation through diverse, wooded terrain. While you can buy specialty clothing and shoes for this kind of activity, from orienteering equipment vendors, you don't need to invest in anything special to get started. You should dress in loose-fitting athletic clothing that you will feel comfortable walking or running in for up to three hours. Most competitors wear either long nylon pants or gaiters to protect their legs from undergrowth like fallen tree branches or sticker vines. Some competitors also choose to wear long sleeve shirts for the same reason. You should wear comfortable trail or running shoes. They should have some tread to handle trail and forest floor conditions, but they do not need to be heavy hiking boots!

Baseplate compass
This simple baseplate compass sells for under $15.

You will need a magnetic compass to help navigate in the woods. A simple baseplate compass will work fine and can be purchased in many retail stores for $15 or less. You need a marking pen or pencil of some sort to draw bearings on a topographic map. You should carry a whistle, in case you fall and are injured on course and need emergency assistance. You should also have a watch so you know how long you have been on course. You want to make sure that you return to the finish line under the time limit (or at least before the search and rescue team is sent out to look for you!)

What else should you bring on course? If you expect to be out on course for more than an hour, you should carry water, either in a water bottle that you can carry in a waist pack or in a hydration system you carry on your back. You might want to stuff a bite-size candy bar or some salty trail mix in a pocket if you think you will be on course for a long time - you can burn a lot of calories and lose a lot of sodium in three hours! On sunny/hot days, a hat and/or sunscreen might be a very good idea - even though a lot of your travel will be under the forest canopy, trails and meadows can expose you to a lot of direct sunlight.

Get Started!

ARDF is a very approachable and fun amateur sport. While the radio equipment you need to participate is not very common, neither is it very expensive. You can save money by building from kits or designs available on the web. Even buying radios built, tested, and ready to go, the cost is quite moderate compared to other Amateur Radio activities. Add in the cost of a magnetic compass, a water bottle, and some simple clothes and shoes for running through the woods, and ARDF is still a small investment in big fun!

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Send comments to: Ken Harker WM5R wm5r@wm5r.org
Last updated: 12 May 2008