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PI7ALK Beacons - PI7ALK
Written by PH0V   


Beacon PI7ALK on 2320,920 Mc operational.

The 13 cm and 3 cm beaons are operational!! On the 10th of april 2010 around 13.00 hrs the mains switch hjas been put to "on-air". Both beacons are operating on a height of approximately 35 m above street level. Frequency 2320,9198 on 13 cm and 10368.931 on 3 cm (according to PA0EZ). Locator JO22IP, power on 13 cm  4,5 W, antenne Slotted waveguide, gain about 4,5 dB omni horizontal. Reports are most welcom on:

Future beacon 1296,920 Mhz. Also plans for beacons on 9 cm, 6 cm en 1,5 cm (24 Ghz). All PI7ALK.

What happend in the past:

For a long time most UHF - SHF hams knew the beacons in Zandvoort on 70, 23 en 13 cm. But since Arie PA0QHN passed away a few years ago his beacons were not maintained anymore. At this moment, 16-th of april 2010, the 70 cm baken is still on-air and workes fine, 23 cm is very week and the 13 cm beacon is off-air for some years.

Ruud, PE1BTV has got in touch with the holder of the licences in 2008 and proposed the repair or building of new beacons to get every PI7QHN beacon operational again, this after cheching with me about the feasability of this job. This proposal is (of course) accepted by the licence holder of the 3 beacons. The 13 cm beacon was our first goal since this was off-air for a longer period allready. Below some pictures about what has been done since.

The long tinned box on the left is the oscillator designed by Sam G4DDK, it contains a Butler oscillator using 2 BFY 90 transistors. This oscillator has been replaced later with an OCXO, designed by G8ACE. This signal is been FSK modulated with the callsign PI7ALK. The callsign generator came also from the UK and is a circuit around a PIC processor, such as designed by Dave WW2R (G4FRE). The oscillator signal then is multiplied in the left tinned box several times finally to 2320 MHz with an output level of about 8 mW.

On the heathsink next to this, the signal is amplified (box in the middle) by an ERA5 and an RF2126 to approximately 600 mW. The final stage is an amplifier using an MGF0905 Fet (special gift for this beacon done by PA0HSM tnx Hans). Now an output level of 4,5W has been achieved. On the very right a small PCB is mounted on this PA, this produces the nessesary supplies for the MGF0905, + 9,5V and - 5V.  On this PCB a special security circuit is made to prevent the FET whenever the - 5V is failing, the + 9,5V then will be limited. This circuit has allready proven it self, because due to a short circuit of an tantalium capacitor the  -5V was failing after some hours during test. The MGF 0905 has survived perfectally.

Finally; the instalation of this beacon will not be at Zandvoort. In spite of all promises by the licence holder, no action has been seen from him since. Our goal now is the install the beacons in Alkmaar on the same location as the 70 cm FM repeater PI2ALK. The call PI7ALK will be used. At this moment 2 beacons are operational from 10-th of april 2010 on 13 cm and 3 cm.

Last Updated on Thursday, 02 June 2016 21:32
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