[time-nuts] Ettus OctoClock measurements

Anders Wallin anders.e.e.wallin at gmail.com
Thu Sep 15 04:23:46 EDT 2016


>
> > The results are decent but not stellar:
> > http://www.anderswallin.net/2016/09/ettus-octoclock-
> distribution-amplifier/
> > In particular the AM noise on the 10MHz looks high. Any
> thoughts/comments?
>
> I am not surprised. They used a digital clock distribution chip. The chip
> is not designed for lowest phase noise, neither is the surrounding
> electronics.
> And selling that whole thing, which is nothing more than the example
> circuit
> in the datasheet, for 1700 is a bit of a rip-off, IMHO.
>

In fairness my link was to the version also containing a GPSDO.
The price I see on the web for only the distribution amplifier is 960 eur.
Timetech and/or Microsemi are probably better - at a higher cost.


> IIRC your design beats theirs already in performance, doesn't it?
>

Yes, my prototype of the TADD-1 design with an AD8055 op-amp, powered from
a +12VDC battery, and wrapped in alu-foil to shield, looked quite good:
http://www.anderswallin.net/wp-content/uploads/2015/12/alufoil_and_battery.png
The 6502 is better and I opened it up to find it has an LMH6702 input stage
and LMH6609 output stages.
I will try that at some point.

Anders


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