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Monster Media 1993 #2
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DF1
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1993-07-08
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34 lines
DF1
Ramsey Electronics DF-1 Radio Direction Finder
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The DF-1 Radio Direction Finder allows you to track down hidden or unknown
radio transmitters using the Phase Difference method.Two antennas are switched
back and forth rapidly,and if the antenas are not the same distance away from
the transmitter,a phase modulation is developed in the received frequency.
This phase modulation can be demodulated on any FM receiver.This demodulated
siganl is a tone with a specific phase in reference to the rate at which the
antennas are being switched.As the antenna array is shifted to the left or
right,the resulting audio also shifts.This shift in phase is detected and
displayed via a LEFT and RIGHT LED display.
The construction of the kit is easy,and all parts are included,except
the case and mounting structure for the antenna array.The Ramsey instructions
reccomend 1/2 inch PVC pipe for mounting the antenna arrays and the optional
model CDF case.
I found an error in the assembly instructions,step #34.The VR1 voltage
requlator should be mounted with the tab towards the INSIDE of the board,
not outside as indicated in the assembly instructions.
The kit functions very well,and has enabled me to locate several noisy
CATV connections on various telephone poles that were disrupting 2 meter
reception in my area.
The DF-1 kit is about $60,matching CDF case is about $13 and the 1/2
PVC pipe aand TEE connectors and endcaps came out to under $5.
Total cost for the entire project is about $80 and you end up with a
valuable tool to locate interference sources,accidental or intentional.
The address and phone number for Ramsey Electronics can be obtained from
most any issue of QST,CQ or 73 Magazine.
Paul,N2MOD @ NY2S.#NLI.NY.USA.NA