Use and Construction of A Noise Sniffer

Figures 4 & 5 Antenna Sniffer, And Checking For Noise On A Wire:

USE AND CONSTRUCTION OF A NOISE "SNIFFER"
The antenna sniffer can be used along with the vehicle's Radio to locate "hot spots" which are generating Radio noise interference. These "hot spots" can be found in the harnesses, in the upper part of the dash or even between the hood and windshield.

The sniffer can be made from an old piece of antenna lead-in from a mast or power antenna. The longer the lead-in the better.

Make the antenna sniffer as shown in Figure 4 in the accompanying image. The 2" section with the black coating and braided shield stripped back becomes the antenna when the sniffer is plugged into the Radio's antenna socket. It can then be used to probe and search out "hot spots."

To use the noise sniffer:

1. While listening to the complaint noise, disconnect the antenna and plug the sniffer into the antenna socket.
2. Turn the Radio volume up.
3. Search for the noise source, keeping fingers off the 2" probe.

When checking for noise on a wire, the best results will be achieved when the sniffer is placed parallel to the wire, see Figure 5 in the accompanying image.

USE AND CONSTRUCTION OF A HAND HELD NOISE "SNIFFER"
A noise sniffer can be built from a personal AM/FM stereo cassette player.


EQUIPMENT
^ Personal AM/FM stereo cassette tape player with headphones
^ Four feet of 75 ohm antenna coax
^ One-half inch heat shrink tube the same diameter as the coax
^ A drill and bit the same diameter as the coax
^ Book of matches or hair dryer
^ Soldering iron and solder

INSTRUCTION FOR THE PERSONAL TYPE RADIO
1. Strip 1/4" off both ends of the coax.
2. Place the heat shrink over one end of the bare wire. Fasten the heat shrink to the wire by heating it (a match or a hair dryer).
3. Disassemble the Radio and locate the antenna.
4. Disconnect the antenna and fasten the bare end of the coax to the antenna mount. A soldering iron may be needed.
5. Feed the coax to the exterior of the Radio. Drill a feed hole if necessary.
6. Reassemble the Radio.

To use the Radio sniffer, turn the Radio on AM and select an appropriate station.

INSTRUCTION FOR THE PERSONAL TYPE CASSETTE
1. Strip 1/4" off each end of coax.
2. Disassemble the cassette deck and locate the tape head.
3. Remove the head and mount one end of the coax to this point. A soldering iron may be needed.
4. Feed the coax to the exterior of the cassette deck. Drill a feed hole if it is needed.
5. Reassemble the cassette deck.
6. Feed the heat shrink tube through the other end of the coax. DO NOT FASTEN THE HEAT SHRINK.
7. Fasten the head to the open end of the coax. Use a soldering iron.
8. Cover the exposed wires between the head and the wire by positioning the heat shrink tube and heating it.

To use the cassette sniffer, push "play." It will work on the same idea as a metal detector.