Circle On Reader Service Card

Homing i

Radio Direction Finding

Joe Moell RE. K0OV P. O. Box 2508 Fullerton CA 92837 [email protected]] lomtngin/]

New sporting goods for foxhunting

Looking for a great way to get young people interested in ham radio and electronics? Take them out lo hunt hidden transmitters! What better way is there to hook them than the adventure, mystery and challenge of locating the source of signals with radio direction finding (RDF) equipment?

In dozens of nations around the world, amateur RDF (called foxhunting, radio-orienteering and ARDF) is a popular sport for youth. Events in these countries are similar to orienteering competitions. About half a dozen low-powered transmitters

(foxes) are concealed throughout a large park or forest. They transmit one at a time, in numbered sequence, on the same frequency. Contestants see how many they can locate in a prescribed time period, usually about two hours.

Radio-orienteering has been most popular in eastern Europe, China, Japan and former Soviet Union countries. It's now catching on in North America, Of course, you don't have to have formal championships just so [he kids in vour school, club or Scout group can enjoy the fun. All you have lo do is scatter some little two-meter transmitters in a park, give 'em some gear and turn 'em loose!

Wrightsville Beach Pussy
Photo A* Besides RDF on 146 and 440 MHz, you can use a dualhand Arrow yogi in a portable s ate [the station for OSCAR modes B and J, as shown here.
Photo ti. The SAR2 i55 MHz yagi and $AR's two-meter version look almost the same. They provide both improved communication range and RDF capabilityt

What gear?

In general, the better your equipment, the more fun you'll have. Ordinary handie-talkies and scanners will get you started on two meters. Simple techniques such as body shielding provide useful bearings under most circumstances. A directional gaii i antenna makes bearings more accurate and helps detect and track very low-poweT foxes. Yagis of two to four elements arc a popular choice.

Grade school kids won't think it's fun to hold a heavy object as they walk in the woods, so a yagi should be as light as possible. Arrow Antenna™ yagis have elements made from aluminum arrow shafts. Such elements are quite strong, but are about half the weight of an equivalent piece of ordinary tubular aluminum (Photo A),

The latest Arrow product is the Model 146/437-10. It has three two-meter elements and seven 70 cm elements on the same boom, with separate gamma matches and feedline terminations, You can track a two-meter signal on its fundamental, then quickly switch to ihu third harmonic as you close in, when the fundamental overpowers your receiver The price of this 19-ouncc dual-band yagi is $73. Single-band models are also available, starting at $49 for three elements on two meters, weighing 15 ounces. For more information, contact Allen Lowe N01MW at Arrow Antenna, 1803 S. Greeley Highway #Bt Cheyenne WY 82007; tel. (307) 638-2369,

A new entry into the lightweight antenna market is Super Antenna Resources (SAR), run by Paul Andreasen KIJAN and Cari Calos KE6CCV (Photo it). Their primary product is the SAR2, a 155 MHz three-element ^agi built on ii 54-inch tapered aluminum boom that doubles as a walking and I racking stick. It weighs 15 ounces and costs about $70. The gamma match assembly is pre-luned for easy assembly in the field.

Cabeo Industries, manufacturer of SAR antennas, welcomes custom orders for beams from 84 to 940 MHz. You can gel a yagi w ithout the long boom tip for T-hunting, or with a square boom for fixed-station mast mounting. For more information, write to SAR. P.O. Box 2610, Lompoc CA 93438; or call Cabco at (805) 736-0662 and ask for Carl.

For use by kids and adults in woodland fox hunts, a yagi's boom should be no longer than necessary. The photos show yagis being held by the supplied hand grips on the boom ends, but it wilt be easier for children to use them i f you attach a mast ofPVC pipe to ihe balance point on the hoom. With it, they can carry and rotate the antenna [ike a flagpole in a parade,

Caution: Eye protection snould always he worn when running or walking with a VHF beam antenna,

A signal sirength indicator (S-meter) is an important feature to have on the receiver you use for on-foot foxhunting. You'll also want to have u way to reduce signal strength as you approach the fox, to prevent receiver overload and help you take close-in bearings, Offset-iype RF attenuators work best for on-loot two-meter RDF. More information on them is in recent editions o! The ARRL Handbook and "Homing In" Tor July 1994.

All in one

Championship foxhunters know ihat a receiver/antenna combination w ith good direct i\ -ity, a wide range RF gam control and an accurate strength indicator makes ihem more efficient and proficient it's also much easier for beginners to track signals using such a one-piece integrated device.

In every country where ARDF has high participation, special RDF receiver/antenna sets, kit or factory-built, are readily available. Some of them, such as the Altai-144 from Russia, lack the selectivity to perform well in crowded US band conditions. Mizuho in Japan makes an excellent ARDF set. but its price approximates that of a dualband handie-talkie. Foreign built/tested ARDF sets arc not sold widely in the USA because of the small perceived market and the cost of mandatory FCC Part 15 receiver certification.

New "single chip" circuits make it possible to produce small VHF receivers with excellent sensitivity and selectivity at modest cost. So far, no LIS manufacturer has put a set with special A RDF features, such as audio S-meter and wide-range attenuator, into its product line, but a good one is available "Down Under." it's made and sold in kit form by Ron Graham Electronics t RUE). Ron VK4BRG welcomes stateside orders.

Photo C show s the complete receiver (Model RX-I) and antenna (Model ANT 1/144) combination. The 11-ounce antenna features the classic HB9CV design with two driven elements spaced ten inches apart and fed out of phase so that the directional pattern is cardioid (heart-shaped). In other words, it has one forward gain lobe and one null in the back. Ron's design is optimized for best pattern (front-to-back ratio) at the expense of some gain reduction. The compact spacing of a two-meter IIBCJCV antenna makes ii a popular choice among ARDF champions around the worid,

For crashing through the brx^h. many foxhunters prefer antenna elements of curved steel tape that give w ay to foliage and snap back into place. Long elements of tape do not retain shape well, so the RGE beam has elements that are half nxt half tape. This is a good compromise, The flexible ends are covered w ith tough sleeving. They screw onto and off the rxIs for easy disassembly and transport. The RX-1 is designed around the Motorola MC3362 dual-conversion receiver IC. A dualgate MOSFET in the front end makes this a "hot" receiver; mine achieved 0.1 microvolt sensitivity. An LM386 audio driver provides plenty of sound in the headphones. The wide range (more than 100 dB) RF gain circuit controls Gate 2 of the MOSFET and stages w ithin the MC3362. It can knock dow n a 350.000 microvolt signal enough to get a good bearing.

Instead of a panel S-meter. which is relatively fragile and difficult to watch while navigating through the woods, the RX-I has a tone-pitch S-meter mode. As signal strength increases, the tone goes from a low growl to a high whine, then to supersonic frequencies. Australians call this the hoopee" mode because of ihe whooping tones the user hears while sweeping the beam across an incoming signal.

The receiver kit includes all parts including the double-sided circuit board and a 4-_Vft- h\ 2 3/K- by 1 -3/16-inch aluminum box with all holes pre-drilled and tapped (Photo Dj. Labeling of the controls is done simply with two printed overlap s. each with a clear plastic cover. It's not as elegant as dry transfer lettering or engraving, but the marks are very easy to read, if you seal the edges of the clear covers, you won't have to worry about rain or wear erasing the lettering.

Although not step-by-step lor each part, the kit s instructions are readily understandable. A VHF receiver like this is probably not a good first project for someone new to electronics, but if you have a couple of successful kits under your belt or if you hav e on experienced Elmer to help you. there should be no problem building and testing this set.

If you have or can borrow a stable VHF signal generator and VHF frequency counter tune-up is simple. With just a liule back* ajid-forth tweaking of the capacitors and inductors (Photo E), 1 achieved full sensitivity and good selectivity. The audio S-meter is so sensitive thai signals of 0*15 microvolt cause the growl pitch to increase. The front-to-back ratio of Ihe antenna represents several octaves of pitch change.

Off to the hunt!

I Ising the RGE set to get bearings is simple and intuim e. Set the RF gain to maximum and

Photo C> The Ron Graham Elic (mrt'Oftics At 'o-nteier reccn Vi7i antenna set is designed for championship competitors. Ihe optional wooden hamite may he useful to some. hut I have since removed it and just hold ii hy the end of its short hoom.

tune in the fox signal while listening on the phones. Sw itc h to the "w hoopec * mode, reduce the RF gain control for a low audio tone and readjust the tuning control for highest pitch to center the signal. Now take bearings by turning the antenna in Azimuth and listening for the highest tone, adjusting the RF gain control as necessary if the tone gets too high or too low.

Be sutc to check with the antenna in both horizontal and vertical orientations and use whichever polarization prov ides the greatest signal (highest tone). Then walk toward the signal source (the direction of highest tone), reducing

Audible Vhf Field Strength
Photo D. The RX-J is about the size of a cigarette pack and weighs twelve ounces. It includes a full-range attenuator and audible strength indicator (VCO mode).
Hb9cv Foxhunter

Photo Ii. Interior view of the RX-I receiver. The MC3362 IC is volta^e-tuncd, A linear potentiometer on the cover is the frequency control.

the RF gain control when the pitcli ¿icis loo high as you approach the fox. After a bit of experience, you'll be able to roughly judge distance to the fox based on the setting of the RF gain control.

With supplied components, the RX-1 co%crsonly about 60% of the two-meter band. The dial marks are 144.0 to 146,5. but you can change the range by renin ing the inductor in the first local oscillator stage of the MC3362, Ii is possible to change fixed resistor values in the tuning circuit to increase coverage to the full 4 Ml Iz, but the singleturn frequency adjust potentiometer is already a bit touchy and this would make it even more so. Some Australian users have replaced this potentiometer with a ten-turn *4knob pot" to give more band spread and make it easier lo find the hunt frequency.

Voltage ro the local oscillator is well regulated, so tuning remain^ rock-solid as battery voltage falls from 9 V to 6.5 V. At 32 miilliamperes typical current drain, battery life should be about 14 hours. Sensitivity falls off slightly as bailer) voltage droops to 7.5 V, then it diminishes more rapidly. It's down 15 dB at 7 V and 30 dB near end of life at 6t5 V The battery mounts externally in us own cradk\ where it's very easy eo replace, even in the middle of a foxhunt.

Resting (no signal) pitch of the audio S-meter also drops lower as the batterv drains. You r can use this characteristic as a good indicator of battery status. Q of the tuned circuits in the preamp stage is such that sensitivity fulls off about 6 dB at the band edges uhen peaked at band center This is not a problem under most foxhunt conditions.

In many countries, two-meter fox transmitters use amplitude modulation. For this reason and to simplify the audio S-meter function, the RX-1 has an AM detector siaae. You can tune slightly off frequency to "slope detect'1 FM signals. This is good enough to identify a hidden transmitter signal from others tin the band, but you won't want to use this set to monitor your local repeater

Europe an/Asian fox hunters use headphones so that their "whoopee" indications aren't heard by other competitors. The RX-1 is intended for headphone listening, too. They aren't sup* plied, but inexpensive Walkman™ types work fine. The LM3S6 output has enough power to drive a small speaker, but there's no room for it in the box. waterproofing would be a problem, and battery life would suffer So stick with the phones.

Besides radio-orienteering, a one-piece RDF ser like the RX-I is ideal for "sniffing out the bu tiny" at the end of your club's mobile hidden transmitter hunts. I have used it on several recent southern California T-hums with

On the Go

Mobile? Portable and Emergency Operation

Steve Nowak KE8YN 5 1153 Malabar Road NE Palm Bay FL 32907

Little or no warning

At times, ii seems thai science is getting better at predicting the type of situations where we might be called upon to serve-The ability Lo predict hurricanes has seemed to improve over the last few years, but then scientists discover the El Nino, La Nina phenomenon, and new questions arc suddenly raised. Earthquake predictions, on the other hand, ha^e generally been less than opiimaL Nevertheless, we can be lulled into a false sense of securit} that we will get adequate w am ing of an impending disaster

How does this affect us in our efforts to provide emergency communications? While amateur radio is primarily a hobby, it is one of those thai can place significant demands on us - Let's compare this with oilier hobbies. A running enthusiast who wishes to run in a marathon (or even a 10 kilometer race) practices, trains, and prepares for the race for weeks or months before the day the race is to be run, He or she may prepare a training schedule which not only addresses physical training requirements but also a dietary plan, and culminates on the da\ of the hie race. The idea of a race being called with onh a few hours'

notice would be absurd. On the other hand, much of the time we are called upon to assisi in emergency communications, ii is with little or no warning.

Disaster or emergency communications support can be as physically, emotionally, and psychologically demanding as an athletic contest. Itis not unusual to be called upon to work long hours for several da>s providing communiculions under austere conditions. How can we train for our potential communications marathon? Here are a tew suggestions:

L Try to use those skills you would need to use in an emergency.

2. Try lo simulate some ol ihe actual conditions you would encounter.

3. Try to promote the art and science of amateur radio.

Many of us are fairly comIbil-ablc chatting on the local repeater, or rag-chewing on the low bands. Hams describe their equipment, where they arc, w hat they 're doing. Conversations arc good results. In one case, the hidden antenna was mounted to be polarized at 45 degrees, between horizontal and vertical. Itiis w as immediately evident as 1 began ihe on-fooi portion of the hunt, and I got nearly perfect bearings by canting the RGB antenna to match the 43 degree polarization.

Once constructed and tuned Up by a competent builder, the RGE receiver/antenna combination is a sensitive, effective and easy-to-use RDF tool for two meters. Total cost of the receiver kitn antenna and: shipping is about 150 US dollars, For more information, write to Ron Graham, Box 323. Sarin a, 4737, Queensland. Australia. Ron has a Web site; you can get there by link from ihe "Homing In" site.

Dale Hunt WB6BYU look his RX-1 to Japan in September for an international foxhunt sponsored by the Friendship Amateur Radio Society. Read about Dale's experiences and aboui plans for a multi-nation foxhuni on I S soil in next month's "Homing in/'

casual and spontaneous. This makes for interesting conversation and is appropriate most of the time. However, during emergency communications we need xo modify operating procedure to be concise and accurate. A great way 10 practice i his is during network operation. When the ARES, RACES, or repeater net is running, try to practice this style of communication. Perhaps net control would divide the net into two segments, the first requiring emergency-style communications, the latter he-ing more social. The informal portion might be the lime to include announcements or the swap and shop segment.

Use public sen ice events for practice, When providing communications for a road race or a parade, agree to use the emergency style during the actual event. Before the event actually begins, and after it ends, drop back 10 a more casual siyle,

Another skill that may need to be worked on is to actually copy, in writing, the activity heiird on the air. During a loca! net^ preferably one where you do not recognize everyone's name and callsign as soon as they start speaking, try logging callsigns, names, locations, and the time they checked in. When you feel comfortable with thai, offer to fill in as net control on occasion. As hard as it is to believe, most ner control operators sometimes work late, have equipment problems, and even lake the occasional vacation.

What about the conditions you might face in a real disaster? Don't count on the local repeaters being operational. How effective will the nel be without the repeater? Neil Sedotal KC5BLQ, the Emergency Coordinator for the Baton Rouge area, periodically calls the emergency net on the usual repeater, then instructs all stations to go to buttery power on a simplex frequency. This can be a real eye-opener as to how well a particular area would be covered under disaster conditions. While we get a taste of this during

Field Day, it is one thing 10 operate a bank of stations from one location powered by a generator, and quite another to operate on VHP from a number of locations,

Even operating using a battery-operated handie-talkie may not be realistic if you're loading it into a beam at \25 feet. It is better to use the type of antenna you would be using if working from a high school g\mnasium being used as a shelter.

Finally, don't forget that amateur radio is fulfilling a commitment to the community. When operating at a road race or a parade, try to gel the sponsors to include recognition of the fact that communications is being provided by amateur radio. Many times the average citizen is unaware of the fact that hams are providing support. Friendly rivalry among local clubs may cause us to emphasize lhat a particular group ls responsible, which may be meaningless to those outside the hobby. When successful companies advertise, they aim the message at the customer, noi their competitors. This is an excellent time to show others what an important asset we are. Have a banner made up that says in large letters, "Communications Support by Your Amateur Radio Neighbors." The club name can still be included, but shouldn't detract from the main message.

If we could plan effectively forbad weather, Hooding, earth-quakes, or other emergencies, they would not be disasters. They are disasters because they give tittle or no warning. As the Boy Scouts say, "Be Prepared !"

Temporarily off line

On a personal note. I've been cui off a bit from comments for the last month or so because I have been in the process of moving from Louisiana to Florida, This has restricted my ability to get mail, and the phone system where I've been living temporarily is not friendly to the modern on my computer. By the time you read this, I'll be settled in my new home (and hopefully getting my antenna farm transplanted), If you've tried to contact me without success, I apologize. I look forward to your letters, packet messages.

radiograms, and E-maii messages. This is your column as much as it is mine. Please continue to share your ideas, experiences, and suggestions, Like any other ham, 1 do best with two-way communications.

Radio Bookshop

Phunc BÛQ-274 7373 Of tfH-924 D051J. FAX ftfW-924 8613, Or urdrr form w puyc 88 for O«fcriflfi information.

Wayne's Five Buck Books & Stuff:

Boilerplate. 45 of Wayne's ham oriented editorials. Great material for cJub newsletter editors w tio arc always ^bon of impressing items for filler. Submarine Adventures- Wayne's WWI i adventures on the USS Drum SS-228, now on display in Mobile, Alabama,

Wayne's Caribbean Adventures* Scuba diving ami hamming all through ihc Caribbean. 11 islands in 21 days on one trip? You bet, and you can't beat the price either.

Wayne & Sherry *s Travel Diaries. Cheapskate traveling 10 Russia, Europe, and so on. Now. how did Wayne and Sherry fly first class to Munich, drive to Vienna, Krakow. Prague, and back 10 Munich, staying j( excelkni hotels and citing up a storm, alt for under 51 ,000?

Cold Fusion Journal - Issue #20 Read the latest scoop on cold fusion in this whopping 92-page sampie issue. Cold fusion dead.' No way! One-Hour CW Course, How anyone can pass the 5 wpm code tesi with less than one hour of study. This also explains ihe simplesi system for learning the code a I 13- and 20-per ever discovered. Or, do it the old fashioned i ARRL) hard waj and suffer Your choice. Other, Slightly Store Expensive Stuff:

Pure Silver Wire ior making those miracle silver colloids Two 3" lengths of

#10 99,999 pure silver wire $1.1 Should last for years.

Bioekctrifier Hand book. B ack ground, circ uits, uses, etc. $10._


Mu Iti Mode

^ BP-2M MuitiMode $69,95

The best littEe pricket modem ium got beticr' Umldini; on the tradition of Ihc BP-i Packet Modem, ac are ver> proud to announce the BP-1 anil BIJ-2M The BP-2 is new and improved version of our famous BP-1 + while the BlJ-2M expands your horizons even fun her with MulhMode operation! So, wheihcr you have been waiting to automate yo\n CW, checkout AMTOR or just copy Weather Fa* - Now iMhciime for you to jump in and join in all (he fun! f^^^m ff f l~1 Call Today! 1-800-8RAYPAC

iinBflnifMCB >33-97Z2 (MS1 4TJ-G700 Fat 474 6703

J accHPOWATiD Worid Wide Wch: hllp://w*w.tietnjr>nia,com ^PBf j

TtgertfOrtics, Inc. 4Q0 Daily Lnt P.O. Box 5210 Grants Pass. OR 97527

Wü/tiöer 56 on your Feedback card

The Digitrl Port

Jack Heller K87NO 712 Highland Street Carson City NV 89703 [[email protected]

Keep that mail coming

You readers give me some truly great tdeas through your correspondence, ii comes in all flavors, E-mail and snail \ ariety, and there are suggestions and solutions as well as questions. One of the most popular subjects has concerned my occasional omission of ke\ facts such as Internet addresses. For several months, you folks were asking about the address at which to find XPWare (line I in Table 1). By now that has probably fallen off the wish list of most readers, but i hope this chart w ¡11 be of al least some help b> providing lhat and some other addresses of possible interest.

Dan KA3ZOF sent some ideas about solving serial port problems with diagnostic software. He gave me names of software packages. I ran a few searches on the Internet and found them located on a Web site loaded with useful files. The page address is listed on line 2 in ihe chart I found three tiles referred to in Dan s message and downloaded them,

The largest Hie. MO DEM D bO.ZIP, required unzipping with a copy of PKUNZIP from PKWare, I found it to be a very well-written, powerful utility that displays the pons and their addresses and IRQs. and has extensive documentation. More than just a listing of w hat the system is doing, it contains helpful suggestions about configuration, too.

The other two files were also compressed files/ Tie difference was that they were compressed with a different system evidenced by the ARJ extender, There were many files listed with this compression scheme for which 1 did not have the decompression program.

Following a bit of logic, 1 hunted around the site and found a reference to a Main Inde\ page. And there I found the real meat oi ihe site. There are listings of numerous useful utilities to meet the needs of computer users of all types. And. yes. 1 did find the file. ARJ250.EXE, to compress/decompress using the ARJ archive system. It works m a straightforward way—that is, if you consider the use of PKWare as the norm. The commands are similar anyw ay*

Don't try this at home

So that was a good adventure. However, one of the files I downloaded got me in a little trouble, The file MDML1TE, ARJ is a little utility to place a set ofpseudo FCD lights on the screen to show when you: modem is connected or transferring data. Sounds like fun. I made a quick attempt to watch it work w ith the copy of Ba\ Com in this . desktop computer.

in the process, I hooked up the serial cable to the BP-2M, turi ed on the W2At and made a connection to the local PBBS, According to ihe authors of BavCom software, this won't w work while 1 m in a DOS window with Windows™ running, so I had never tried it. But it looked OK and here 1 was. happy as a clam, a* i left to eat dinner w hile the automatic tape backup ran at that time oi evening.

On my return the backup was concluded, but there was something not quite right. The cursor would not respond to the mouse. After going through a lot of extra calisthenics to close open files and shut down the computer, i was sure all would be well.11 Well" is det ined many ways, 1 guess. The mouse functioned after a reboot, but the tab key was executing a peculiar code. After another cofd boot the system settled down, I team very slowiy.

By, now, most of you realize lhat the BajPac™ BP-2M has occupied more ofm> time than 1 would like to admit. As of this writing. I have not gotten the multimode operation (e.g.. AMTOR. RTTY, etc.) to function. The Ham Com ni software package comes with some greai diagnostics, and I think I have isolated the problem, but I am awaiting an E-mail reply from the author, W. F. Schroeder DL5YEC (E-mail is quick, but the ham at the other end must translate my message, determine what I really asked, and then reply in English. I

Along the way, Don KA6LWC sent a note concerning the connec

Line #






Multimode TNC Software


DIY Battery Repair

DIY Battery Repair

You can now recondition your old batteries at home and bring them back to 100 percent of their working condition. This guide will enable you to revive All NiCd batteries regardless of brand and battery volt. It will give you the required information on how to re-energize and revive your NiCd batteries through the RVD process, charging method and charging guidelines.

Get My Free Ebook

Post a comment