El Dorado County Amateur Radio Club

1

• El Dorado County Amateur Radio Club
• 2007 Foxhunt

2

• Foxhunting History and Philosophy

3
Why Foxhunt?What Skills Can be Gained?

• Finding sources of RFI (Radio Frequency
  Interference)
• Search and Rescue location of lost people or
  aircraft in wilderness
• Getting to know your regions back roads
• Raising community awareness of ham radio(what
  are those folks up to?)
• Coordination among a team of hunters
• Having fun with your fellow amateurs

4
EDCARC Past Foxhunts(Courtesy of Bill W6LSW)

• Club conducted regular T-hunts during the 1990s
• Start was breakfast at the Waffle shop near the
  east end of Placerville
• Who ever was hiding the transmitter would leave
  early and hide it, then about 9 or 930 the rest
  of us would begin hunting.
• It was a requirement that you had to be able to
  hear the hidden transmitter there or at some
  designated location.
• Bill (W6LSW) had a timer that would key the
  transmitter and a tape recorder which would turn
  on for approximately 30 seconds.
• The tape played was pre-recorded with suitable ID
  and voice messages that just taunted the
  searchers.

5

• The Rules and Boundaries

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Foxhunt Rules

• The Fox will hide only in an area that is
  accessible to the public without the payment of
  an admission fee.
• This event is a Mobile hunt where participants
  hunt from their vehicles. No walking is required
  to find the fox.
• Hints will be occasionally be given on the FOX
  frequency and on the EDCARC repeater, 147.825, if
  possible. Hunters are encouraged to ask for
  hints if they are lost!

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Foxhunt Rules

• The fox will transmit every 5 minutes for a
  minimum of two minutes.
• The fox frequency will be announced on the
  147.825 repeater at the start of the hunt. The
  hidden transmitter signal must be copyable at the
  starting point by agreement among the hunters
  present. The start point will be at the Federated
  Church, 1031 Thompson Way, Placerville. The hunt
  will be Saturday July 28, 2007. Start time will
  be determined at prior Thursday Club Meeting.
• At the beginning of the hunt each team will
  record their starting odometer reading, to the
  nearest 1/10 mile, to be given to the Huntmaster.
  Hunters will verify their reading to other
  participants if requested.

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Foxhunt Rules (Continued)

• The hunt will have a Maximum Time Limit of 1 hour
  and 30 minutes, at which time the location of the
  FOX will be announced to any remaining hunters.
• So that all teams can hunt with equally high
  enthusiasm, the FOX will not announce that the
  hunters are in the area or that any teams have
  found the fox.
• Upon arriving at the FOX each team will
  immediately check in with the Huntmaster by
  stopping in front of the Mobile FOX, to record
  their time and mileage.
• The team with the lowest true elapsed mileage
  will be the winner.

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Area Covered by Foxhunt(Not to Scale)
Hwy 193
Hwy 49
Hwy 193
Hwy 49
Salmon Falls Road
Hwy 49
El Dorado Hills Blvd
Hwy 50
N
W
E
The fox will be located inside the following
boundary West EDH Blvd, Salmon Falls Road,
and the stretch of Highway 49 between Salmon
Falls Road and Hwy 193. South Hwy 50 East
That stretch of Hwy 49 between Hwy 50 and Hwy
193, Hwy 193.
S
10

• Recommended
• Equipment

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What to Bring (Personal Gear)

• Water
• Sunscreen
• Comfortable clothing and shoes
• Sunhat
• Snacks
• Adequate gasoline for your car
• Camera or Camcorder

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What to Bring(Recommended Radio Gear)

• 2m Transceiver (in car or hand-held)(2m receiver
  will also work)
• Portable directional antenna
• Map of area
• Notepad to copy hints
• Watch
• Compass

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What to Bring(Optional Radio Gear)

• GPS Unit
• Second 2m Transceiver for coordination
• Second team member to drive and navigate
• Cell phone
• Doppler Unit

14

• Building
• The Cheap Foxhunt
• Beam

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Beam Overview

• A simple three element beam can be constructed
  using a steel tape measure (cheap), PVC (real
  cheap), and a few spare parts in our shack.
• The design is courtesy of Joe Leggio WB2HOL and
  is on the websitehttp//home.att.net/jleggio/pr
  ojects/rdf/tape_bm.htm
• The cost is minimal (20 or less) and easy to
  build
• The beam works very well for both transmit and
  receive, with the following performance
  parameters GAIN 7.3 dB
• Front-to-Back Ratio50 dB
• 3 db BeamwidthE 67.5 degrees
• 3 db BeamwidthH 110 degrees

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Beam Parts List

• 4 ft ½ PVC (Schedule 40)
• Qty 2, ½ PVC Crosses
• Qty 1, ½ PVC T-Section
• 10 feet of 1 wide steel tape measure
• Qty 6, 1 ½ auto hose clamps
• 6 household wire
• Electrical tape
• 50W coaxial feedline
• PL239 connector (with coax adapter)
• (If necessary) adaptor for radio (SMA, BNC, etc)

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Beam Construction

• Cut PVC tubes to make understructure. As cross
  and t joints vary in size, cut PVC tube to
  achieve final dimensions when inserted.
• NOTE! Dimensions are to center of joints, NOT to
  joint or tube ends.

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Beam Construction (Cont)

• Trim four pieces of tape measure -Reflector 41
  3/8 long -2 Driven Elements 17 ¾ (you may
  wish to make them longer and tune after
  assembly) -Director 35 1/8 long
• CAUTION Steel tape is sharp. Use safety glasses
  and care when cutting. Tape ends to protect
  yourself and others.
• Center tape measure sections on crosses and t
  joints, and along boom

TAPE ALLEDGES TO AVOID INJURY!
Reflector
Driver 1
Director
Boom
Driver 2
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Beam Construction (Cont)

• Add hose clamps to tape measure elements
• You may need to use electrical tape to keep tape
  measure elements straight (avoid gull-wing effect)

Cross
Hose Clamps
20
Beam Construction (Cont)

• Remove tape measure paint at inside ends of tape
  measure
• Solder 4 ½ hairpin between driven elements

4 ½ long wire
hairpin design
Hairpin location
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Beam Construction (Cont)

• Separate braid and center wire on one end of 50
  Ohm coax cable
• Solder braid to one driver, center wire to other
  driver
• Make sure to remove tape measure paint prior to
  soldering
• Terminate coax appropriately to your radio

50 Ohm Coax
Hairpin location
Braid
Center Wire
22
Beam Construction (Cont)

• Hold you beam via the handle.
• Add a counter weight to end of handle to have
  beam balance when held
• Duct tape and a rock will work just fine!

Antenna Grip Area
Handle
Counter Weight