Re: Pluto via Ethernet - TX dropouts #pluto

Jean (DJ0VL)

The Si5351a works quite well if you use integer divisors, but do not expect any miracles from a $1 chip. As soon as you use fractional-N divisors, spurs show up on the output signal. I did play around quite a while with the SI5351a as a first setup to generate the 25MHz reference signal for the qo-100 RX LNB, however the phase noise gots visible on strong signals due to the x390 multiplacation of the LNB PLL. As there is no information available on the internal PLL and phase comparator, I do not know the  amount of performance degradation when feeding in a 10MHz reference signal instead of using a 25-27MHz XTAL as specified by the datasheet.  

The Leo Bodnar GPSDO is quite popular among Pluto users and is a great device if you need programmable outputs. As is is build around a VCTCXO and a fractional-N synthesizer, I would personally prefer an OCXO based GPSDO if just a single 10MHz output is required.


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