7QNL setup until now

After our arrival (May 21st) in Malawi Remco put of the station as soon as possible and made  a 1/4wl vertical with two elevated radials for 15m in the dark, just to be on the air as soon as possible.

The next two days were spent looking for material to build antennas.

Fortunately ~1000m galvanized iron wire was arranged. Although not optimal, it’s at least something! (velocity factor of this wire was calculated to be 0.99 …)

In two days (yes, this is Africa) four modelled antennas were erected:

For 10, 15, and 20m VDA’s pointing ~335 degrees. These VDA’s perform surprisingly well,despite likely ground conditions (take off angle).

Calculated take off angle is ~18 degrees.

As time was limited, and also daylight, it becomes (very) dark in Malawi ar around 1600 UTC, only 40m was ready for the 24/25 May weekend. The 40m antenna is a deltaloop modelled to 200 Ohms and fed 1/4wl from the apex. Matching is done with a 4:1-balun.

After it was erected the first SSB (!) QSO’s were made into Europe with good signals.

There is heavy QRN on 40m and the four Beverages help siginficantly to pull stations out of the noise.

Remco made a solid state HP amplifier especially for this trip. It has a 2nd generation LDMOS FET, and generates ~700W max with the power supply used with ~70% efficiency.

Unfortunately 80m was not ready for the contest weekend, but the 40m deltaloop pole is 16.5m long, thus when time allows a T-antenna for 80m may be an option.

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