plot
Predicted coverage area

spare
        Main and standby 3cm beacon units

pa
              1W PA and driver module

ant
 3cm Waveguide slot antenna and location

East

south

west
north

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3cm beacon keyer:  IK0WRB

GB3CAM    Cambridge microwave beacons
IO92WI          Wyton           Cambridgeshire                                                                                                         
 
3cm:  10368.755 MHz                                1.2cm:   24048.870 MHz

reports always welcome, either direct ( gb3cam[at]earf.co.uk ) or via www.beaconspot.eu                       
                                                                                                                                                                                      


***** The 3cm beacon will be off during the morning of Thurs 18th September for maintainance *****
                                 NOW BACK ON AIR     plus     24 GHz UP AND RUNNING!                                             

The first of the two Cambridge microwave beacons came on-air on 11th June 2008. This was the 10 GHz
beacon.  Although Wyton is only some 35m asl, the beacon antennas are 30m above ground level - well
above the local tree cover. There is some obstruction due to other antennas on the same site however.
.
beacon-details
 
beacon antennas LHS:  24 GHz multiplier/PA/antenna.                         
RHS:  10 GHz antenna.

These units are mounted on the eastern side of the     
tower (the camera is looking SE).

      3cm 'Spots' added to www.beaconspot.eu                      3cm Beacon frequency error since switch-on
                      as of the 1st May 2009
beaconspot Frequency error  

 
3cm beacon frequency error history (measured every Wednesday against a rubidium standard):
Measurement date
 10.06.08
 16.07.08
 23.07.08
 30.07.08
 06.08.08
 13.08.08
 20.08.08
 27.08.08
 03.09.08
 10.09.08
 17.09.08
 24.09.08
 		01.10.08
 08.10.08
 18.10.08
Error
 -130Hz
 -140 Hz
 -180Hz
 -240Hz
 -260Hz
 -330Hz
 -250Hz
 -360Hz
 -350Hz
 -350Hz
 -440Hz
 -420Hz
 		-370Hz
 -350Hz
 -460Hz

22.10.08
 29.10.08
 05.11.08
 12.11.08
 19.11.08
 26.11.08
 03.12.08
 10.12.08
 17.12.08
 24.12.08
 31.12.08
 07.01.09
 14.01.09
 21.01.09
 28.01.09
 04.02.09
 11.02.09
-490Hz
 -500Hz
 -460Hz
 -480Hz
 -420Hz
 -510Hz
 -480Hz
 -520Hz
 -460Hz
 -510 Hz
 -450Hz
 -510Hz
 -460Hz
 -460Hz
 -510Hz
 -500Hz
 -510Hz

18.02.09
 25.02.09
 04.03.09
 11.03.09
 18.03.09
 25.03.09
 01.04.09
 08.04.09
 15.04.09
 22.04.09
 29.04.09
 06.05.09
 13.05.09
 20.05.09
 27.05.09
 03.06.09
 10.06.09
-390 Hz
 -420Hz
 -450Hz
 -510Hz
 -530Hz
 -480Hz
 -500Hz
 -490Hz
 -490Hz
 -500Hz
 -460Hz
 -460Hz
 -465 Hz
 -470Hz
 -485Hz
 -315Hz
 -390Hz

17.06.09 01.07.09
-420Hz
 -460Hz


The reference oscillator used in this beacon is a 25 year old Racal 9420 unit. It operates at 5 MHz.

A 500 Hz error at 10 GHz equates to a clock that gains or loses 1.5 seconds per year.
For more 1.2cm details see:  http://homepage.ntlworld.com/john.g4bao/page12.htm
For more 3cm details see: http://www.earf.co.uk/3cm_proposal1.htm