GB3WGI Radio Beacon


144 MHz Beacon
Frequency: 144.487MHz
ERP: 30dBW
Heading: 280°
Locator: IO64BL21
Location: Lough Navar
Keeper: Gordon Curry GI6ATZ

The 144 MHz beacon is constructed from a driver designed and built by Andy Talbot G4JNT. More info on the design and construction of the driver can be found here: -

http://www.g4jnt.com/Beacon_Source.pdf


The reference 10 MHz Oscillator for the beacon source is derived from a GPS Disciplined Oscillator designed and built by James Miller G3RUH. More information on the GPSDO can be found here: -

http://www.jrmiller.demon.co.uk/projects/ministd/frqstd.htm

The driver generates both CW and JT65b coding allowing the transmitted signals to be decoded either by ear or by using the WSJT software written by Joe Taylor K1JT: -

http://www.physics.princeton.edu/pulsar/K1JT/wsjt.html

The output of the driver is set to around +13dBm and is feed to a commercial PA with a final RF power of 100 watts.

The beacon transmits JT65b on the even minutes and CW on the odd minutes in the following sequence: -

00:01 – 01:51 GB3WGI IO64BL in JT65b mode
00:52 – 01:03 GB3WGI IO64BL in CW
01:04 – 01:29 Plain Carrier
01:30 – 01:42 GB3WGI IO64BL in CW
01:43 – 02:00 Plain Carrier

The sequence then repeats

To decode the JT65B, tune the carrier to obtain a tone of 1500Hz with the receiver set to USB, and the dial frequency reading 144.4855. The JT65 will then be tuned in correctly.


The antennas used for the 144 MHz beacon are a pair of 6 element Flowa yagis designed by Derek G4CQM and phased using a two-way power divider. The antennas are connected to the power divider using Ecoflex coax.

Roger GW4WND of the DX Shop -
http://www.thedxshop.com - donated the antennas and the power divider.

The antennas are connected to the transmitter using LDF-450 cable.

The yagis are on headings of 280° and are 35 metres above ground level

The Brendan Awards The Brendan Awards are designed to encourage experimentation with two-way trans Atlantic communications by radio amateurs using the Two Metre Band. Further information is available at www.irts.ie/brendan The Brendan Medal is a triennial Medal, awarded to the group or individual who, in the opinion of the Awarding Committee, has contributed most to the promotion of propagation studies on the trans Atlantic two - metre path and to the Brendan Quest. The Awarding Committee has considered the submission of a nomination for the Brendan Medal and has decided that Brian Justin, WA1ZMS, should receive the first Triennial Brendan Medal for his work on setting up and maintaining the trans Atlantic 2 meter beacons. The medal will be presented to Brian by IRTS President Séamus EI8BP during the ARRL Centennial Celebrations in Hartford Connecticut next week. Source: IRTS









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