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Equipment Ideas

As mentioned elsewhere on this site, there is a rumor that transmitter hunting is an expensive aspect of Amateur Radio. This rumor is simply false. Most equipment can be bought surplus, or can be built from scratch, as most of our hunters have done.

Below are various examples of equipment that are either commercially produced our the design data can be found on the web. Sometimes the equipment can be obtained at major ARDF events.

Recommend use (ARDF or CAR hunts) is posted after the name of the item.

Receivers

VHF Hunting

VK3YNG sniffer - (ARDF hunts & Car hunts) This is a new arrival to the DF receiver market. Detailed Information and an instruction manual can be found at the VK3YNG Sniffer website. I found this photo of the sniffer on the VK3YNG website.

Ron Graham Electronics RX1 - (ARDF hunts & Car hunt end point sniffing) This is the 2 meter receiver of choice among many ARDF hunters! The receiver can be used with the optional ANT1 antenna or a Yagi such as the one described below. The receiver is sold in kit or assembled version. More information can be fond on the Ron Graham electronics web site (opens new browser window).

A modification which makes the RX1 PLL tuned was developed by Jerry Boyd, WB8WFK and Mike Pendley, K5ATM. A prototype version was used during the 2001 USA ARDF championships by several team Albuquerque members. The current version being used by team Albuquerque members operates off of 4 NI-Mh Batteries. A DC/DC converter powers the system. More info The LCD Display displays the following data:

Inside view of a RX1 with OZMOD installed. The missing parts are for the circuits that make the PLL work with the Foxfinder-80. Most of the parts are SMT and the board has a silkscreen on both sides.

2-meter Tape Measure Yagi - (ARDF & CAR hunts)This is the antenna of choice among many transmitter hunters! Made from PVC pipe, flexible tape measure material and hose clamps, this three-element yagi is perfect for any 2-meter hunt, and even normal on-air 2-meter operations! More information (opens new browser window).

WB8WFK 2-meter Active Attenuator - (ARDF & CAR hunts)This active attenuator, with a built-in field strength meter, is a must to locate hidden transmitters. This design is compact, and allows you to nearly walk right up to the antenna of the hidden transmitter without overloading your receiver! More information.

W9DUU TDOA - (CAR hunts) This unit is based on an article in the July 1990 issue of 73's amateur radio magazine. Photographed is a version built by WB8WFK that has been modified for low current operation. (LED's and LM339's removed). This unit was originally used for end point sniffing at car hunts. For the original article and circuit description contact 73's for reprints of the article. Not recommend for ARDF as multipath will cause you to louse valuable time. To download is a scanned in schematic for the low current draw WB8WFK version of the TDOA click this link 162KB JPG file.

Doppler - (CAR hunts) This unit is a modified version of the Roanoke Doppler found in Transmitter Hunting Radio Direction Finding Simplified on page 123 and was built by WB8WFK. The K0OV wide band antenna array is also used with this set. Doppler's are good for hunting short duration and strong signals.

Doppler - (CAR hunts) This unit built by Mike Pendley, K5ATM is a more recent design based on the Montreal Doppler. Mike is also using the K0OV wide band array.

 

HF (80 meter) Hunting

PJ-80 - (ARDF)This is a low cost direct conversion 80 meter ARDF receiver. Some of the Albuquerque transmitter hunters purchased them from the USA 2002 ARDF Champs email reflector during the summer of 2002. The receiver suffers from low audio output but its a cheep way to try 80 meter DFing. The receivers described below are better performers.

Dale Hunt WB6BYU - (ARDF)Dale's 80 meter direct conversion receiver is a winner! Its easy to build, operate and best all the cost is low. For information about the receiver design contact Dale WB6BYU Marvin Johnston is offering kits. For information about the kits contact Marvin direct via email. Several Albuquerque Transmitter hunters have assembled some of the kits that Dale had for sale at the 2002 championships in Georgia. The kits are easy to assemble and the receiver performance is very good. This photo is a unit built by WB8WFK before Dale had his circuit board kit versions ready.

WB8WFK Foxfinder 80-meter ARDF Receiver - (ARDF) ARDF enthusiasts will greatly enjoy this received used to DF 80-meter hidden transmitters. It's compact design allows you to easily find the direction of the transmitter by listening for the null, and solving the 180-degree ambiguity by activating the sense antenna at a touch of a button. More information. The Georgia Radio Orienteering Club did a group build of foxfinder-80's as a club project.

Altai-3,5 - (ARDF) This is a Russian made 80 meter direction finding receiver named for a town/region in southern Siberia/northeast Kazakhstan. The unit is easy to hold, even after being on a long course. The nulls are very well defined and the sense antenna is easy to operate. Another nice feature is that the controls are arranged in such a way that they are easy to operate using a single hand. Measured current draw at 9 volts is 15ma. Frequency stability is good. The only part of the receiver that I have problems with are the headphones. They are heavy and bulkily. I obtained my unit at the 2002 USA ARDF championships in Georgia.

 

Transmitters

Albuquerque Amateur Radio Club (AARC) Foxbox (ARDF & CAR hunts). This is the foxbox that our club is currently using for our ARDF and CAR hunts. The box shown to the right is one of 5 which was built by Mike Pendley, K5ATM for use during the 2001 USA ARDF championships in Albuquerque. An additional box also contains spare parts and a battery charger. For 80 Meters the ATX-80 transmitter is used for MOE-MO5 and MO transmitters. One ATX-80 has been modified to hold both crystals and can be field configured by changing a jumper. An Icom HT is used for 2 meters (MOE-MO5). A hamtronics VHF exciter is used for ARDF VHF homing beacon "MO" service. Using A HT is not recommend for VHF "MO" duty. The ATX-80 transmitter can handle "MO" duty. No overheating problems have been encountered. The MO transmitter uses a larger battery then the one shown in the AARC Foxbox photo. The controller is a modified Montreal Fox Controller. A users manual written by Mike Pendley, K5ATM (ms word format)can be downloaded from this site to assist club users with setting up and operating the foxbox. A development effort is in process to design a new FPGA based generation foxbox that is smaller in size and provides more functionality. On air testing started December 2007.

AARC Foxbox ATX-80 transmitter Montreal Fox Controller

 

The equipment mentioned above is used by many of our hunters, who are extremely happy with their use. If you have any questions about any of the equipment, do not hesitate to email us at abqthunt@yahoogroups.com. Enjoy!