Westerbork, Dwingeloo and field day

Some photos made last week.

Close to one of the antenna’s in the Westerbork radio telescope array
Before Westerbork we had Dwingeloo, currently this dish is used by PI9CAM, see also http://www.camras.nl
Fieldday 8-apr-2017
40m elevated ground plane
This is the antenna I tested on the 8th of April and I call it an elevated ground plane for 40m. The essential part is the 9 meter of wire that you loosely wind around the mast. Use an antenna analyzer to tune it. The simplicity is that it works on a glass fiber mast without any guy wires, the tripod at the base is sufficient to keep it upright, secure the tripod with three tent pins. At 9 meter with 5 turns the antenna is resonant in the high part of the 40 meter band. The length of the radials is not critical, the box is a straight through, it has a SO-239 connector, center pin goes to the vertical and there are several bolts with butterfly nuts on which you attach as many radials as you carry, I always carry four of them. At the end of the radials I fix them with a tent pin. The transceiver is kept 20m away with a RG-58u 50 Ohm coax cable which is light and flexible which is ideal for field activities, the transmission line loss at 7100 kHz is negligible, we only run at most 80W on the transceiver and we avoid any tuner. The transceiver was a FT-991 running on a 3S lipo battery 5000 mAh. I got the mast at dx-wire and the batteries at CONRAD.

Last update: 9-April-2017


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