[time-nuts] Effects of noise on EFC line? - Resolved

Alex Pummer alex at pcscons.com
Fri Aug 8 00:27:08 UTC 2014



he is on the right truck, just look around in your testing environment, 
do you have shielded test set up, common ground for all the test gears ?

  On 8/7/2014 3:58 PM, Hal Murray wrote:
> bob at evoria.net said:
>> So, I may throw another cap on it, but it seems to be clean down to what I
>> can measure at the OCXO on my old Tek 455 with an X10 probe.
> Another thing to consider when chasing that sort of problem: How much are you
> picking up with your scope probe and/or its ground wire?
>
> The classic home brew better-probe is to use a chunk of 50 ohm coax feeding
> into scope with a 50 ohm terminator.  (You get 2 of them if you cut a readily
> available connectorized cable in half.)  Insert 950 ohms at the probe end to
> get higher input impedance at the cost of a 20:1 divider.
>    http://www.signalintegrity.com/Pubs/straight/probes.htm
>
> It usually requires soldering at the DUT.  For me, it also requires a mental
> shift.  You have to think of your scope probe as a consumable rather than
> something that won't wear out if you take care of it.  A chunk of coax will
> last a long time.  Just cut off another 1/2 inch when the end gets too
> mangled.
>
>




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