[time-nuts] I can't get a nice waveform from my rubidium !

GandalfG8 at aol.com GandalfG8 at aol.com
Thu Apr 17 04:06:34 EDT 2014


Hi Claude
 
I don't have any specific experience of this unit but suspect your  problem 
may be down to impedance matching.
 
The manual for the Quartzlock A10-M specifies the output impedance as  
being 50 ohms nominal and it would be reasonable to assume this is the  same.
 
Scope inputs and scope probes won't present such a low impedance so the use 
 of a coaxial pass through 50 ohm termination would be my first suggestion, 
if  you haven't got one to hand just try hanging a 50 ohm  resistor, 
anywhere between 47 and 56 ohms say, across the output and  ground and monitoring 
across that.
 
This is quite a common problem, especially on supposedly square wave  
outputs, so chances are your unit is fine.
 
Regards
 
Nigel
GM8PZR
 
 
 
In a message dated 17/04/2014 08:17:12 GMT Daylight Time, labtf1 at yahoo.fr  
writes:

Hello  List,
I've recently bought a Quartzlock 10A R (rubidium). Does anyone has  
experience with this unit? 

My
unit has two outputs with no options.  The problem is the shape of the 
waveform (see attachments), it's the same  shape for the two outputs. 
When I
connect an output directly to the  oscilloscope, the shape is nearly 
"squared" and when I use a probe, the  shape is nearly "sine" !

When I send a 10 MHz signal from a generator,  the waveform is a clean sine 
with or whithout the probe.

So what signal  should I except from this rubidium ? Or most probably, what 
is wrong with my  use of the oscilloscope ?
(The frequency is ok by the way (+2E-10) and I  didn't open the case yet) 

Thanks for any  advice

Claude


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