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I now have built up a useful programmable signal generator from the PLL. The whole of the PLL area of the pcb was cut out and leads were attached to connect to a PIC microcontroller. Four push buttons and an LCD complete the design. By adding a diode harmonic generator output to at least 24GHz is easily attainable - DETAILS TO FOLLOW. - 12 July 2001
I recently got hold of one of those -now unused- house mounted boxes which contains a microwave link and were used instead of a land line.
I wonder how many have been prying inside them? there are quite a number of useful bits :-
1. A good weatherproof case
2. A switched mode power supply
3. A programmable microwave PLL -Mine produces 1660MHz
4. A DSP processor and reprogrammable EEPROM
..... as well as all sorts of other less useful bits and pieces tuned to frequencies like 1.9GHz.
I have managed to get the unit working after a fashion by injecting 5v directly onto the regulator output - this operated the PLL etc.
What I don't yet know is the normal input voltage to the PSU. Try as I might I haven't yet managed to get the Switch Mode PSU working. So far I've had up to 25v on the input with no effect and little current drawn. - it may be that there is an enable line which I haven't yet dicovered.
Looks like it could be the basis of a 2.3 or 3.4 Transverter or beacon.
Anyone out there working on these units - perhaps someone just possesses one - drop me a line for a chat - perhaps we can make some progress?
fig1- PCB space allocation
Antenna/connector/diplexer- The antenna is a broadband printed array which terminated in a connector to the Diplexer filter on the PCB.
LO. This is probably the most useful part of the whole unit.It consists of an adjustable 10MHz refence oscillator feeding a (NS) Microwave PLL chip. The whole thing is serially programmable via the DSP processor (but could equally well be fed from a PIC chip. I have considered just cutting this part out and driving it from a PIC. I don't know the range of the VFO included - it has 620-1720 on the case- it may be the specified frequency range. The synthesizer will go up to 2.5GHz.
DSP - The DSP processor is a powerful and well documanted AD device - however the associated AT&T device is unknown
SMPSU- This should be easy to get working but has so far kept me guessing
Interface connector - a few of the connections have been deduced but there are a greater number of unknowns here. The power supply can't be too high a voltage since the creepage distances are limited by the EEC low voltage directive. I would guess at no more than 48 Volts.
Last updated 2001 July 12