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This is an excellent DF unit once you get close to your objective.  Its operation is as simple as you could hope for.  It does not have the long range accuracy to replace a unit such as the Little L-Per, but once you're at a row of hangars or at the marina there is no equal.


There is a good DF sniffer--not as accurate as the L-Per but REALLY quick and intuitive at close range--see the stuff at:
If you build the sniffer, I have some specifics to make it work on 121.5 MHz. Its a cool device!


Bob Dehner showed me the antenna you'd loaned him at NESA.  It looked good and was directive enough to work pretty good with the Mk4 Sniffer I brought (and also loaned him).  I've been building PVC & Measuring Tape antennas for the Sniffer and am looking into using 3 layers of tape to make them stronger but still collapsible.  I'd like to play with design you used (maybe even looking into making the elements detachable), especially given the reduced spacing between the driven element and director element.

Do you have any info on the antenna design you could provide?

 Attached are the dimensions for the measuring tape antenna.  I now use clear heatshrink over all the 5.5" pieces and place reflective tape under it to augment safety.  I sent the info to Scott Lanis last year, but apparently it got lost along the way.  The Sniffer User Manual (and associated links) is at:

Building the 121.5 Antenna for the Viking powerpoint presentation







This page of the CAP Emergency Services Resources website was last updated 01/06/2009

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