A few days ago, I had a post about the new proposed 2m beacon for St Helena Island. Dee, ZR1DEE has very kindly sent on some additional information.
Garry, ZD7GWM is the beacon keeper and recently took delivery of a Motorola GM340 FM radio, power supply, cables and a Diamond X700H antenna.
As of the 4th of February, the antenna still needs to be installed and then the beacon will be turned on.
More info from Dee.....
Now we wait for the Diamond antenna to be erected and BEACON SWITCHED ON
The keyer circuit is a 8 pin PIC12F675 chip fed to the input of the Motorola GM340 FM radio
Call sign of the beacon ZD7GWM
QRG – 144.475 frequency
Grid locator IH74DB
QTH LONGWOOD ISLAND OF ST HELENA
Antenna type DIAMOND X700H
Height above sea level 545M
Height above ground 10M
Antenna direction OMNI-DIRECTIONAL
Horizontal or Vertical VERTICAL
Power output 20 W
Keying – mode CW
Machine Generated Mode if applicable
GPS coordinated S 15⁰ 56’ 54.68 W005⁰ 41’ 02.34 (-15.9485 -005.6840 )
Beacon status activated soon
Beacon Keeper GARRY MERCURY ZD7GWM
Analysis... Let's have a look at where St Helena is and who is likely to hear this beacon.
As the map shows, St Helena Island is a lonely spot situated way out in the South Atlantic Ocean and it's a long way from everywhere.
Tropo... The coast off the west coast of South Africa and Namibia has some excellent conditions for marine ducting of VHF & UHF signals at times and the path from South Africa to St Helena has already been bridged on 144 MHz and 433 MHz. It's likely that the new beacon will be very useful as a propagation indicator for these type of openings.
Looking further north, the path to the African coast is in the region of 2500kms but it's likely that a lack of active stations in these coastal states will be a limiting factor. The dominance of low pressure systems close to the equator may also be a factor in preventing long distance tropo paths.
The path to D4VHF on the Cape Verde Islands is over 4000 kms and probably unlikely.
The real test however will be the path to Brazil in South America. Is it possible??
As the map shows above, there is a 2000km stretch of Brazilian coastline which is about 3500kms from St Helena. While the north-west corner of Brazil is about 400kms closer, it is also closer to the Equator and the low pressure area. My own guess is that the more southerly Brazilian stations might have a better chance of hearing the St Helena beacon on 144 MHz.
There is also the chance of some Sporadic-E at these latitudes which might help with 2000kms or so of any path. Between a combination of Sporadic-E and some marine ducting, I suspect the path to Brazil should be possible.
Trans-Equatorial Propagation (TEP)... Another possible path is via TEP to an area around the south of Spain.
At 144 MHz, TEP signals need to be close to 90 degrees to the Geomagnetic Equator. St Helena Island is about 16 degrees south of geographical equator. The Geomagnetic Equator is about 10 degrees north in this part of Africa so the equidistant point to the north is at 36 degrees latitude which is in the Straits of Gibraltar.
Is it possible for stations in that part of the world (EA7, EA5, CT, ZB2, CN or EA9) to hear the St Helen beacon on 144 MHz??
We'll have to wait and see. It'll be interesting to see who hears the beacon and how often.
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Additional information from Dee, ZR1DEE....
Greetings All! Beacon for St Helena Island and more….
Kobus ZS3JPY was instrumental in restarting up having a beacon for St Helena Island. Well, the time has come, and it is happening as history is being made!
Now, let’s follow the journey of the beacon and more….
Channel 1: 144.475