Bloomington Amateur Radio Association

Transmitter Hunt Practice Saturday 9/21

Weather Update

Despite rain in the morning, the activity is go for a 1:00 PM start time.

Details

There was a lot of interest in the hidden transmitter hunt last week. At our monthly meeting, there were requests for a program on the final few meters of searching, covering both theory and practice. Accordingly, at 1:00 PM CDT on Saturday, September 21st we will have a hidden transmitter hunt (2-meter) practice session in Tarnhill Park (98th St. and Little Rd.) in Bloomington. The practice session will focus on on-foot techniques and relatively simple equipment. Bring what transmitter hunting equipment you have; there will be some extra gear available for use.

This is a fair-weather activity, and a final go/no-go decision will be made by 7 AM CDT on Saturday 9/21 and propagated on the BARA website post for this event.

Techniques

• Built-in attenuator
• Polarization
• Third (and other) harmonic hunting
• Slight frequency offsets
• Body fade
• Triangulation
• Hunting with an omnidirectional antenna
• Step attenuators (PDF)
• Offset attenuators

Frequencies:

• 146.565 MHz transmitter
• 439.695 MHz 3rd harmonic
• 293.130 MHz 2nd harmonic
• 147.090 MHz (+600 kHz, no tone) voice repeater

Updates:

Go/No-go weather decision has been made, activity is go for 1:00 PM start time.

Hidden Transmitter Hunt Thursday 8/29

Overview:
With a stretch of nice weather in the forecast, it’s time to dust off the transmitter hunting gear! This Thursday (8/29/19), the Bloomington Amateur Radio Association will be hosting a transmitter hunt, beginning at 6:30 PM at Bloomington Civic Plaza from the parking lot on the west side of the building (near the southwest entrance).

The field of play will be the City of Bloomington, bounded on the west by US HWY 169, to the north by I-494, and to the south and east by the Minnesota River.

Format: Two hidden transmitters; one 500 mW to 1 W, the other 10-20 mW and in the general vicinity of the stronger transmitter. The transmitters will be on alternate 1-minute transmit windows.

Accessibility: A vehicle will be required for finding the transmitters, but at-home operators (in Bloomington and possibly surrounding municipalities) with omnidirectional or directional antennas can still contribute with coordinated hunting (see Resources below for tips from WB4APR). On-foot hunting is expected to take up to a mile of walking on sidewalks, dirt/grass paths, or over cut grass.

Difficulty: This is intended to be a beginner-friendly event, and those without directional antennas are encouraged to take part in a coordinated hunt (see Resources below). With sunset at 7:56 PM, the event will be complete around 8:00–8:15 PM.

Frequencies:
Two hidden transmitters: 146.565 MHz FM
Safety and administrative: 147.090 MHz, +600 kHz, no tone, analog FM (KD0CL VHF repeater)
Coordinated hunting: 443.175 MHz, +5 MHz, DCS 047 (TX and RX), analog FM (KD0CL UHF repeater; repeater is Yaesu C4FM capable, but please use analog for this event)

Resources:
Homing In, and specifically this page on first-time hunting techniques and equipment.
Bob Bruninga’s (WB4APR) Direction Finding Tips for those with Omnidirectional Antennas.
K6KN’s Presentation for SFARC on Transmitter Hunting.

Map:
Parks, roads, and lakes of Bloomington (PDF).

Contact:
Bill; AE0EE[at]arrl.net

Updates:
8/26/19 0105z: Added K6KN presentation link.
8/26/19 1846z: WB9CFN looking for teammate.
8/28/19 1652z: Added printable map of Bloomington.
8/29/19 1746z: Corrected UHF repeater frequency, 444.375 443.175 MHz.
8/29/19 2105z: Updated printable map to be more grayscale friendly.

Further updates will be added to this post on the BARA website.