| Predicted
coverage area |
|
Main and standby 3cm beacon units |
|
1W PA and driver module |
| 3cm Waveguide
slot antenna and location |
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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 first of the two Cambridge microwave beacons came on-air on 10th July 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.
.
It
is hoped that the 24 GHz beacon will go live some time in August 2008.
'Spots'
added to www.beaconspot.eu within first week of operation (3cm)
| Measurent 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 |
| Error |
-130Hz |
-140 Hz |
-180Hz |
-240Hz |
-260Hz |
-330Hz |
-250Hz |
-360Hz |
[This is quite an error, and does not relate well to what was found during initial soak testing (less than 100 Hz error). The
5 MHz reference is quite elderly (at least 25 year old), and the coarse tune trimmer is a little intermittant, so I believe all the
mechanical bumps of moving the beacon onto site has upset the trimmer - certainly the temperature excursions on the new
site are noticeably less than during soak testing]
For
more 3cm details see: http://www.earf.co.uk/3cm_proposal1.htm