GPS

GPS locked, 10Mhz standard to lock the local oscillators so that the beacons can be used as an off air frequency reference.
The GPS locked Reference oscillator will be a stand alone unit that will have slave outputs for each beacon.
1pps output of the GPS so we'll have a VNG like time pulse to broadcast rather than just CW, this will reduce the PA's duty cycle to about 30 -50% depending on how wide we make the "second" pulse.

FLASH CRYSTAL

From Expanded Spectrum Systems, their Flash Crystal and their Freaking
Beacon controller. More info on both units can be found at this URL...

http://www.expandedspectrumsystems.com/

INTERSTAGE AMPLIFIER

The ERA5 interstage amplifier is a local product from VK5EME,
more info can be found at this URL...

http://www.minikits.com.au/kits2.html

PROGRAMMABLE ATTENUATOR

The programmable attenuator we can either build ourselves or use a
MiniCircuits ZSAT-31R5, these can be often found on eBay for a
reasonable price.

DRIVEN AMPLIFIER & BAND PASS FILTER

The buffer amp could be built from a Motorola M67710L on a Down East Microwave PCB part number DEM2303, both available from RF parts in the
US, see this URL for more info.....

http://www.rfparts.com/pcb.html

The BPF ( Band Pass Filter) we would have to design and build ourselves, plenty of circuits in ARRL and RSGB manuals and stacks on the net.

PA STAGE & COUPLER & OUTPUT FILTERS

I'm aiming for an ERP of 100 watts on each band so we'll need about 50w at output - this is very easily attained.

The Final PA, we could either build or buy. I recently picked up such an amp for $55 off eBay, much cheaper than buying the bits to build it.

The coupler we could build or buy.

Each beacon will have band pass filters on output to ensure harmonics, sidebands etc are negligible.

POLARISATION

Horizontal polarisation, omni directional antenna for each band,
Probably slot radiators for 23 and 13cms

EXTRA

Each beacon will can be switched between either the external reference or its own internal unit so it can operate out of the rack for testing etc.

Each beacon will control its output in 10db steps so that for any 1minute of transmission 15 secs will be spent at full power, 10db, 20db and then 30db down before returning to full power for ident.

Modular construction with interchangeable sub components to minimise cost.

Where possible, each sub component will be a kit of some for so that as many people as possible who can weild a sodlering iron can take part in building these units.

The ident switch we will build and the Vreg circuit and the REF Failure Detect circuits are all simple and can be either built from our junk boxes onto bits of vero board or buy some of the simple kits from JayCar.

The switched mode PSU we will have to buy too - dont think too many people would like to try their hands at building on of those :).

Using this design we only have to put triplers, doublers etc after the attentuator, to get to the other frequencies.

I'd also like to have each beacon built into a 2RU rack mount case. 

While it may be a bit expensive to head down this road, it will give as many members as possible some hand in creating these projects rather than just the few of us with all the skills.

At the completion of each beacon I'd like to have all the callsigns engraved on the front panel or back panel or inside to recognise the contribution of everyone who helped in its construction.

I want our members to look at or hear on air these things and be able to say " I helped make that!"

We can do this :)

regards

TIM TUCK VK2XTT