Coming Events

KARTS & AWA Flea Market and Open Day

The Kempton Park Amateur Radio Technical Society (KARTS) and the Antique Wireless Association (AWA) combined flea market and open day event will take place on Saturday 24 May 2014 from 08:00

The venue is the Impala Voortrekkers Centre, Rooibos Avenue, Allen Grove, Kempton Park. Please visit the KARTS website at for directions to the venue.

Apart from the flea market, a display of antique radios and associated equipment will be put together as well as an active HF + V/UHF station from where the Saturday AWA SSB net will be operated.
This event promises to be a most interesting, enjoyable and memorable day.

For table bookings or any queries, contact Selwyn ZS6SEL at 082 804 2782 or email to This email address is being protected from spambots. You need JavaScript enabled to view it. or Nico ZS6QL at 083 269 9939 or email to This email address is being protected from spambots. You need JavaScript enabled to view it.

KARTS and the AWA are looking forward to welcome you there!

Alexanderson Day

Alexanderson Day will be held on Sunday 29 June this year. This day commemmorates the Swedish radio engineer Ernst Alexanderson and is celebrated by having an open house at the Swedish VLF transmitter, Grimeton. The transmitter operates on 17.2 kHz with the call-sign "SAQ".

Alas, it probably can't be heard in South Africa (Please someone prove me wrong.)

The remarkable thing about this transmitter is that the signal is produced by a rotating machine called an Alexanderson alternator. In essence this is a series of rotating iron discs swith cut-outs arounds the periphery. The field coils are also placed on the periphery and the iron induces an alternating voltage of very high frequency in the field coils. The spaces between the cut-outs are filled with non-magnetic gunmetal to reduce air-resistance.

The signal can be received using a tuned circuit attached to a PC sound card. A program such as "Spectrum Lab" can be used to decode the transmission. There's even an SAQ receiver script for this software.

Alternatively, a TRF receiver could be used.

For those who like to experiment, a stepper motor from an old disk drive can be used as a high frequency alternator, but keeping the frequency steady is another thing altogether.