This contest is simple, and is designed to teach you the basics of VHF/UHF transmitter direction finding and hunting.
To participate in the RF foxhunt you will need a radio or a scanner that can receive signals in the 2m and/or 70cm Amateur Radio Bands (144.000 MHz - 146.000 MHz, 420.000 MHZ - 450.000 MHz). To participate in the IR foxhunt you will need a device that can receive IR light in the 900nm range.
This contest uses custom built VHF/UHF transmitters from VA7IF, along with the Byonics MicroFox VHF transmitters, both are a purpose-built transmitter designed for Fox Hunting and ADRF. These units transmit between 15 mW and 500mW of energy, and they will burst a short message in CW (Morse Code) approximately every 15 seconds. Each of the six transmitters will use a different frequency in order not to confuse their individual locations. This year we have added an additional type of fox to the hunt, a type of Infra Red LED transmitter! The IR LED transmitter beacon is a small plastic case with a hole for a single IR LED. It has a sticker that reads "I'm an IRLED". It transmits a message coded in standard morse. What is the code and what easter egg might it reveal?
This is the inside of the unit.
The units will be in a casing like this.
When you locate the transmitter, please be kind to other participants (and to the Contest), and do not remove it, switch it off or otherwise tamper with it. There is no prize for first place or the shortest hunt. Everyone who participates and finds the transmitters will receive a small commemorative trophy!
So here's the fun part - you don't need fancy antennas or complex/expensive gear to find many foxes. All you need is you, a radio, and patience!
The technique you should use (if you're new to this - if you're not, why are you still reading? Go find the foxes!) is called Body Fade. In a nutshell, you are using your body itself to block as much signal as possible in order to give you a vector to search towards. Hold your radio close to your chest while slowly turning in a circle when you hear the transmission from the fox.
You're looking for the direction where your body blocks most or all of the signal (the "null" or "signal null"). Some radios will have a signal strength meter that you can watch, or you can adjust the Squelch on your radio while listening until the transmission no longer breaks the squelch. What does that mean? Well, that means the signal should be directly behind you - so do a 180 turn and walk for a bit.
After walking for a short moment, repeat the body fade technique to ensure you're still heading in the right direction. The signal should increase in strength. Note that the null you've created with your body is quite shallow. It can sometimes pick up signal reflections off of RF-reflective surfaces. If you are not getting a good null, reflections might be an issue: just move to a "clearer" location and try again.
When you've reached a place where the signal is so strong that you can't find a null, tune your radio 5 or 10 KHz off frequency. This should help find a null, but this depends on the quality of the bandpass filter on your radio. to put the signal into the skirts of the receiver's IF passband. If your hand-held is dual-band (144/440 MHz), try tuning to the much weaker third harmonic of the signal in the 70 cm band while performing the body fade technique.
Disconnecting the radio's antenna will knock down the signal even more. If you hear the signal with the antenna off? Look around you, you're probably within a few feet of the fox.
Congratulations! You're now a Fox Hunter! No DCFurs were harmed in this hunt!
The contest table will be staffed from 10:00 - 11:30 and 14:00 - 15:30 local time Friday. You can come by to discuss your hunt, and you can collect your trophy.
On day two, the Foxes will get substantially more difficult to locate.... So come back to the website Saturday morning for a more difficult challenge, if you're up for it!
The foxes will be transmitting codewords plus N3RTH. These frequencies are subject to change but will most likely be within a few megahertz of listed frequencies. Keep an eye on the daily notices and re-check the website for any updates. Record the codewords and bring them to our booth for lame prizes and more!
146.565 MHz
146.565 MHz
145.430 MHz
446.025 MHz
446.175 MHz
446.325 MHz
Please take the time to stop by our booth for info, tips & tricks and more. We're located in the central section of the main contest area of the Caesars Forum.
Day 1 of the Ham Radio Fox Hunt was a great success! Thanks to all the folks for coming by our booth and inquiring about the contests and participating in the hunt! Tommorow will be even better with more hidden foxes in new locations with new codes. Don't worry the frequencies haven't changed(much). Stop by and say hello during contest hour 10am-6pm. 73 VA3MXY
Thanks for your interest and/or participation in the annual Defcon Fox Hunt! Your involvement has kept this contest alive and energized over the years, we look forward to your future involvement so please spread the word!
73's!
-The Defcon Foxhunt Team
VA7SHX/N3RTH