JUMA DRF1 is a stand alone direction finder receiver for 160 and 80 metes.
It is mainly designed for man made interference finding and it can be also used as a general receiver on the go.
Click DFR1 picture to enlarge
The loop dimension is 26cm x 26cm. Total height is abt 39cm.
The antenna is a four turn magnetic loop made of two layer FR4 PCB which provides good sensitivity.
The two band analog DSB receiver is implemented in the handle with a 9V battery and a small speaker.
Best listening experience can be achieved with phones plugged into the 3.5mm stereo jack.
The antenna is mechanically very symmetrical and the coupling is electrically well balanced
which provides a deep minimum during direction finding.
The tuning of the magnetic loop and the frequency is using capacitance diodes.
The VFO control has coarse and fine tuning potentiometers.
The gain adjust range is is wide to hear a low level interference as well as a strong signal.
The directivity is best for ground wave signals like near by man made interference sources.
The signals coming via ionosphere have many arriving angles which doesn't provide a reliable directivity.
Documents download (PDF ans Excel)
Schematics PDF
PCB top layout PDF
PCB bottom Layout PDF
Front panel PCB PDF
Part list Excel
Update 2020-11-28 OH7SV
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