The AD9850 DDS Board is now with the PCB manufacturers. I went there
yesterday to check the solder mask, and had a fascinating trip round the
factory looking at PCB manufacture and SMT component pick and place
mounting. Delivery is still quoted as 30 days so we have about 3 - 4
weeks left as these are being batched with other PCBs.
Price of the PCB will probably be £8.00, plus p&p whatever that will
come out at. HF Instruments will also coordinate a bulk purchase of
AD9850 chips and some AD9851 devices too (see below), prices still to be
fixed. I have also been told that it will be possible to supply chips
mounted on the PCB for those frightened by the thought of soldering 28
0.65mm spaced pins - although its not as difficult as you might think
especially with a solder mask there to help avoid shorts underneath.
The AD9851 DDS chip is pin compatible with the AD9850 device and has an
internal x6 clock multiplier allowing it to be used with up to a 30 MHz
oscillator to give a clock freqeuncy to 180 MHz - output range can then
go from DC to 70 MHz in steps of 0.04 Hz. For LF use however, I would
still recommend the AD9850 device with a drive frequency of 4 - 5 MHz
giving mHz steps.
One interesting aspect that comes out of the 9851 data sheet is the use
of the aliassed DDS products, after bandPASS filtering, to generate
frequencies in the VHF range up to 100s of MHz. Very useful to
microwavers.
Andy G4JNT
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