[time-nuts] 10811 changing frequency when load impedance changes ?

[Mark Spencer]

Thanks..  

I'll likely do some more testing with the 50 ohm load in place and see how 
stable this unit is before investing more time in this.    


----- Original Message ----
From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
To: Discussion of precise time and frequency measurement <time-nuts at febo.com>
Sent: Fri, December 24, 2010 10:05:51 PM
Subject: Re: [time-nuts] 10811 changing frequency when load impedance changes ?

Mark Spencer wrote:
> Seasons greetings.  
> I was pleasantly surprised to find that a new to me HP 5328A had an 10811 in
> it.    (I was expecting the older OCXO..)    After leaving it running for a
> week I adjusted the frequency and while doing so I noticed that the out put
> frequency changes by a third of a hz or so if I add or remove a 50 ohm load.  
>I'm measuring the frequency at the timebase output connection of the
> 5328A.  Is this to be expected ?
> 
> Many thanks
> Mark Spencer
> 
> 
> 
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>    
No, that seems to be a couple of orders of magnitude larger than the specs for 
the 10811A would lead one to believe.
Maybe there's a problem with the output buffer amp in the 10811A?

Bruce


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