EMRFD Message Archive 10749

Message Date From Subject
10749 2015-01-22 07:33:24 Chris Howard w0ep general question about DDS chips and such
For the various varieties of programmable frequency sources,
the Si5351A, Si570, the Analog Devices DDS chips, etc.

Is it safe to assume that they can run on a lower frequency
clock (C < Cmax) and then produce outputs scaled by
C/Cmax ?
10750 2015-01-22 08:26:23 Dana Myers Re: general question about DDS chips and such
10751 2015-01-22 10:37:04 jorschei Re: general question about DDS chips and such


The Si570 has a internal X-tal thad cannot be replaced. The Si5351A has a external X-tal as reference and it possible to test a higher or lower frequency X-tal. The data sheet say 25 or 27 MHz, bud it is interesting to test how high or low the x-tal frequency can be used outside the specification, and measure the harmonics and noise (jitter) of the output. In theory if the the x-tall is 50 MHz and twice the divider for the same output frequency may be the noise will be lower, bud experiments will give the answer. The same for lower x-tal frequency's.

73"  Joris PE1KTH