19 Feb 2015 – A Talk Out of a Hat

Aerials at Grimeton
Aerials at Grimeton

The first topic was ‘did you hear SAQ?’  Some did and some didn’t.  Victor, G3JNB used his Spectrum VLF up converter and could hear at about S2 or so.  Ian, G3ORG used a general coverage receiver that could tune 17.2 kHz without a converter and with his 500ft longwire could copy at RST 589!  Various other methods were tried, Bryan, M0BIK used the SDR programme suggested on the SAQ website with an indoor wire and I tried the online SDR provided at www.websdr.org     but neither could hear a signal.  Victor provided a recording of the transmitted message and Ian described the giant Alexanderson alternator, one of many around the world, however this is the only working model. More details can be found at: http://www.grimeton.info/world_heritage_grimeton.html

Richard, G3NII then described the problems associated with high powered pumps driven at variable speeds and the large current spikes, as large as 400 Amps, which causes interference in the control circuitry.  The problem was cured by using better screening on the cables.  We didn’t get around to a Talk out of a Hat, which we will do another time.

Alexanderson alternator at Grimeton
Alexanderson alternator at Grimeton