View Full Version : Fox Hunting for Randall County

04-23-2011, 01:09 PM
On April 10, 2011, Amarillo area amateur radio operators (hams) were asked to assist in tracking down a signal which was jamming the input frequency of the Randall County Fire Department repeater by using radio direction finding (http://en.wikipedia.org/wiki/Direction_finding) techniques known as Fox Hunting (http://en.wikipedia.org/wiki/Transmitter_hunting). Numerous hams across Amarillo provided signal reports from their fixed and mobile stations which indicated the interfering signal was not coming from inside the city limits. Armed with mobile rigs and high gain mobile antennas, KE5WXN and W5MJM of Amarillo were able to determine that the signal became audible while heading south from Amarillo at about McCormick Road and Interstate-27, and the signal increased as they continued South. Onboard a DPS helicopter, KC5HQY was able to further determine that the interfering signal was originating from Happy, TX. KE5ZRT and KE5ZRU, using a directional homebrew tape measure beam antenna (http://www.ccars.org/Projects/TapeYagi/index.htm) (on loan from N5LUL) and a handheld transceiver, were able to isolate the signal to within 50 yards of the source of the interference which was determined to be one of two locations in Happy, TX. By tuning slightly off frequency and removing the rubber-duck antenna from a handheld transceiver, and through the process of elimination, N5SUJ and W5AMA were able to successfully isolate and terminate the source of the interfering signal which was determined to be a decommissioned county repeater with an opposite frequency pair, known as an extender. This was an excellent opportunity for local hams to serve their community by putting their amateur radio skills to use in a real-world application.

Andy N1ORK
04-23-2011, 06:22 PM
Great job people! Love those tape measure yagis, I've built 3 of them.