[Aavso-sid-list] SID receivers

[Rodney Howe]

Francois,

I think Dusty sent you the AAVSO web sites for the Gyrator II. It is the
radio some of the SID group have been using, perhaps it would be worth
trying. For example:

http://www.qsl.net/SARA/projects/vlfrx.htm

A group in North America also detected the SGR1806-20 'super flare'
magnetar. I was fortunate enough to record a strong signal with the Gyrator
II and a 1.5 meter loop antenna.

http://www.aavso.org/observing/programs/solar/sid-sgr1806.shtml

I think there have been three GRB or X-ray transient detections so far with
these VLF radios (SGR1806-20, SGR1900+14, GRB030329). These have been long
hard bursts: It seems it is not so much the distance from receiver to
transmitter as the geometry of where the GRB event took place during the
daytime, where you are [the receiver], and where the transmitter is
located. If these are in 'line', then detection may be possible, see:

http://var.astro.cz/oejv/issues/oejv0022.pdf


rodney howe




>Hi SID Monitors !!
>
>For the last few years,I have been scanning the Internet for possible SID
>receiver circuit diagrammes, in an attempt to improve what I currently
>use. I am using a homebrewed received based on a SEA receiver from the
>early seventies. This receiver consist of two tuned ferrite pot cores
>around an opamp,then into a two diode detector followed by a DC amp.
>Antennas are  DIP switch tuned amplified loops with a 75cm diameter
>
>I am getting very good results from NWC on 19.8 kHz (9363 km) and good
>results from  NAA on 24.0 kHz (11461 km). But the question that came up in
>my mind is : now that solar activity is down and the easy flares are gone
>as well, is it possible to come up with  a "new" design that will still be
>technically possible,even in a far-off country like mine ?? I have tried
>the direct circuits using op-amps,ones with tunable inductors,superhets
>and even a SA612 DC receiver....... This may also be used for GRB
>detection ?? I am trying to get reception from VTX3 in India at 7555 km or
>possibly LeBlanc,France at 9100 km. Will I get "better" results if I tune
>to a more distant station or to a more local one ?
>
>Unfortunately I have no contact with the other AAVSO SID monitor here in
>South Africa so I cannot confirm any results.
>
>I am watching with interest any feedback !
>
>Regards,
>
>Francois Steyn
>Villiersdorp
>South Africa