[time-nuts] New 10mhz Distribution Amplifier

Bruce Griffiths bruce.griffiths at xtra.co.nz
Thu Aug 14 18:46:07 EDT 2008


Rick Karlquist wrote:
> Additional specs to consider:
>
> The return loss should be low for 10 MHz and the first 8 harmonics.
> The harmonic distortion should be low.
> The isolation between outputs should be high.
> The phase drift vs temperature should be low.
> The short term stability at 1 second should be good.
> The magnetic field susceptibility should be low.
> Line sidebands should be low.
>
> Compare, for example, the HP5087, a so-so design, to the
> output amplifier design in the 5071A cesium, as documented
> in my FCS paper in 1992.  Huge difference in specs.  The
> 5071A has 120 dB isolation between outputs.
>
> Rick Karlquist N6RK
>
>
>   
Rick

Did you mean a high return loss or equivalently low reflection coefficient?

The layout of the board in the picture is perhaps preliminary the input 
signal track to 3 of the output sections is a little too close to 
another track.

Its hard to tell from the low res image but have thick film resistors 
been used?
These can have excessive flicker noise thus increasing the close in 
phase noise above that possible with thin film resistors.

Bruce



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