[time-nuts] New 10mhz Distribution Amplifier

Rick Karlquist richard at karlquist.com
Thu Aug 14 19:13:58 EDT 2008

I should have said the return loss should be "high" or "good" :-)

Bruce Griffiths wrote:
> 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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