Piedmont Transmitter Tracking

Piedmont Transmitter Tracking

William B. Umstead State Park, NC
April 16, 2000

For the second time in 15 days a record was set for the number of transmitters in a North Carolina transmitter hunt. William B. Umstead State Park, between Raleigh and Durham, was the site for this Raleigh Amateur Radio Society event marking National Foxhunt Weekend. Observers and participants added up to fourteen individuals, easily outnumbering the six transmitters hidden in the park.

The format for this hunt was in some respects quite similar to an international-style Amateur Radio Direction Finding competition. Umstead Park is, in fact, large enough to host a genuine ARDF hunt. But for this hunt, the area was restricted to a region roughly 500 meters in diameter. All the transmitters were placed within 20 meters of a foot path, so that no serious off-trail hiking was required. (Which is not to say that some hunters didn't take some serious off-trail hikes!) The six transmitters were divided evenly among two different frequencies: 146.565 MHz and 146.500 MHz. A 30-second transmit period was used, so hunters needed to wait only one minute for a transmitter to come back on the air after completing its transmission.

Photo © KN4AQ
Matt Cooney,
Chris Lawless,
Jacob Holbrook,
Rick Holbrook, strategize before the hunt.
Photo © KN4AQ
John Swartz, James Heinis scrutinize signal strength.

The transmitters consisted of five Alinco DJ-S11 HT's with built-in antennas running 50 mW, and one crystal-type Wilson 1402SM HT with rubber ducky, running about 1.5 watts. Each transmitter was controlled by a Montreal Fox Controller, with customized software that allowed the transmit interval to be adjusted. The transmitters were placed in the park on the morning of the hunt, and individual travel alarm clock turn-on circuits activated them all simultaneously 15 minutes before the hunt started.

Photo © KN4AQ
Decoy or real McCoy?
Photo © KN4AQ
Chris Petrich "logs" another find.
Photo © KN4AQ
Hmm, which bag would you bag?

For beginning hunters, two of the transmitters were placed within 150 feet of the starting point. To make things interesting, a dozen decoy transmitters were spread out among those two transmitters. Each transmitter, and each decoy transmitter, had a 3 x 5 card with a unique 2-letter "control mark" identification printed on it. Participants were awarded a point for each transmitter's control mark they recorded on their score card. A point was deducted for any decoy transmitter control marks they recorded.

Photo © KN4AQ
This decoy was a real stumper.

Photo © KN4AQ
Chris Petrich bags a live one.

Photo © KN4AQ
"Is your radio saying what my radio's saying?"

The remaining four transmitters were located in wooded areas within the park, between 200 and 400 meters from the starting point. The red circles on this map show the positions of the transmitters.

Many participants were experiencing their first taste of on-foot transmitter hunting, and as the results show, everyone experienced the taste of victory over at least one transmitter.

Results
Individual	Call	Club	Real Foxes	False Foxes	Score	Time
Fred Decker	N4IXL	RARS	6	0	6	90
Chris Petrich	no call	-	5	0	5	89
John Swartz, James Heinis	KB1DLB, WA4RCU	-	2	1	1	88
Chris Lawless, Matt Cooney, Jacob Holbrook, Rick Holbrook	no call	OCRA	2	1	1	97
Byron King, Mark Gibson	K4NGJ, N4MQU	JARS	1	0	1	100
Renard DellaFave	KC4AQC	-	1	0	1	110
John M. Guerriero	KG4HDT	-	Observer	-	-	-
Dave Humphries	G4ETG	-	Observer	-	-	-
Gary Pearce	KN4AQ	RARS	Observer	-	-	-

Photo © KN4AQ
KB1DLB, WA4RCU
prepare their hunting gear.

Photo © KN4AQ
KB1DLB, NZ0I,
WA4RCU

Equipment used by the hunters ranged from body-fading, to a four-element log periodic beam. Most hunters favored the WB2HOL tape measure yagi and an offset attenuator. Tracking the third harmonic was a helpful technique for several hunters.

My sincere thanks and congratulations go to everyone who participated. Special thanks to Gary Pearce, KN4AQ, for capturing the action with his digital camera, and to the Raleigh Amateur Radio Society who sponsored the event. Thanks also to the Backwoods Orienteering Klub, of Raleigh, NC, for providing custom orienteering maps, and to Superintendent Martha Woods, and Ranger Bob Davies, of Umstead State Park for their support before and during the event.

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