Have fun with this basic handheld radio direction finder!
H.F. Pix The HANDI-Finder ®
This Radio Direction Finder Device Connects to an FM Receiver, Transceiver, or HT

HF Layout
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Click here to print or download
the full view layout drawing
from a PDF file
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HF Layout


The HANDI-Finder®

The HANDI-Finder® is a HANdheld DIrection Finder which can be used to localize both AM and FM carrier-based sources using a single connection to the antenna input of an FM receiver tuned to the frequency of interest in the range of 45 to 450 MHz. It has been designed for bare-bone functionality as well as low power consumption, simplicity, and economy!

Because it is both an easy-to-build kit for the beginner and a convenient basis for further experimentation by those with more experience, it makes a great club project! Overall, it is a quick, inexpensive way to implement the concept of direction finding, and provides something relatively compact to keep readily available for locating sources of interference.

Except for adding a handle, fabrication is minimal. Two open-loop antennas are made from coat hanger wire bent into halves of a "bow-tie" shape and mounted directly to the circuit board, as illustrated in the "layout" drawing.

The coax downlead is connected to an FM receiver and detects the carrier regardless of whether the transmission mode is AM or FM. The unit is switched on (UP) and rotated for a null in the audio tone that it adds to the audio coming out the receiver. The signal direction is perpendicular to the plane of the antennas. There is 180-degree ambiguity, but this is not a problem in actual use because multiple "bearings" must be taken anyway in order to establish a "fix" on the location. Once close in, the operator works toward the general sense of the direction, and again the ambiguity is not a problem.

The 3-position switch is moved DOWN to stop the tone but still keeps the antenna activated for monitoring and standby purposes, --or it is moved to the CENTER position to shut off the unit. Refer to the extensive discussion in the manual which describes construction variations, and the concepts behind the design.

"Build the HANDI-Finder" appeared as an article in QST Magazine, May, 1993.  All the information in that article and much more is included here! By clicking on the appropriate boxes in this web page, all the drawings and text that come with the kit can be printed out or downloaded from PDF files.


HANDI-Finder® Experimenter's Kits
may be obtained by contacting:

Northern Ohio Amateur Radio Development

P. O. Box 271
Brunswick,  OH  44212-0271  USA
Tel: 330-225-7373   


Click here for prices and order info:

www.noard.com

Click here to open an HTM file
that will allow you to read and print
the Instruction Manual		 Click here for quick full-size
view of the SCHEMATIC

Click here to open a PDF file
that will allow you to read, print,
and download the SCHEMATIC		 Click here to open a PDF file
that will allow you to read, print,
and download the Kit Parts List

This is the HANDI-Finder® information webpage.   We would love to hear from you!  Please tell us how you discovered this website, and what you would like to see added to it.  Perhaps you have interesting experiences using the HANDI-Finder® that we could share with others.

This page was last updated Aug 11, 2006 at 0900 local time.

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RALTEC® and HANDI-Finder® are TRADEMARKS registered with the U.S. Patent and Trademark Office




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