Martlesham Microwave Beacons Update

John Quarmby

We braved the winds today and managed to get the antennas for the GB3MHS
3.4GHz beacon installed, and re-installed the 10GHz Beacon at the same time.
We also checked and reset all the beacons using a GPS locked frequency
counter, so they should be very close to their nominal frequencies now.

The new GB3MHS 3.4GHz beacon uses a DB6NT beacon tansmitter unit feeding an
ex-Ionica PA module. This is followed by an 8 cavity filter (again ex Ionica
Base station), and produces about 10W at the output connector. Keying is
courtesy of a WW2R/G4FRE PIC keyer. The antennas are also ex Ionica (thanks
to Mark GM4ISM), with 14dBi gain and 120 degree horizontal beamwidth. One
beams East (covers 030 to 150 degrees), the other West (210 to 330 degrees),
and taking into account feeder losses the EIRP is about 75W. Reception
reports will be very welcome.

On 10GHz the outdoor multiplier/PA unit has been re-built by Sam G4DDK to
include a PA module donated by G4BAH and now produces 500mW at the antenna,
giving an EIRP of about 5W, a 7dB increase on the previous system. We hope
that the increased power will be useful for spotting rainscatter conditions.
Again, reception reports by email or on the DXCluster are always

The beacons are located 10km East of Ipswich in JO02PB.


John G3XDY
Martlesham Beacon Keeper

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