> Hello Janne, > > welcome to the group which, I am sure, will benefit from any >contribution you will give. > >The AD9954 should have the same core of the AD9951. This latter has >been used by Giuliano I0CG in his SDR-X receiver, with a clock of 500 >MHz. The SDR-X can receive up to the 6m band, so the DDS must be able >to generate at least up to 51 * 4 = 204 MHz, and actually it is. >At that frequency there are much more spurs than at lower >frequencies, >but in any case the spurs level is lower than in the much celebrated >SDR-1000. >Giuliano told me that it tested the AD9951 even at 600 MHz clock >frequency, and it continued to work, though it is spec'ed only up to >400 MHz. > >Good luck with your project. > >73 Alberto I2PHD >
Hi Alberto! Thanks for the reply. So, it would be possible then. It might be wise to make pcb with just one AD9954 and test it with, lets say 550 MHz clock signal. If it doesn't work well enough, just put another PCB back to back and make it IQ pair. The thing is, that here in Finland 6 meters go as high as 51.990, which is the output section for repeaters. So, I need 208 MHz to cover that up. Best choise of course would be to use pair of AD9954, but I'm a bit afraid of the complexity, because I haven't done anything with DDS before. Also the synchronization, 90 degree phase shift for a first DDS project, including the register stuff, sounds too complicated :-/ But I'm also afraid that going the easy way might bring as much problems, hihi. 73 de Janne, OH1GTF
