[time-nuts] EFC divider resistors

[Bob Stewart]

As to what the specs are on this oscillator, I couldn't say.  I have two of them.  The one in my GPSDO wants about 2.101V for 10MHz.  The other one wants about 2.6V (from memory).  So that pretty much limits my options to a divider and a summing device to bring the EFC back up for the oscillator.  And, that's my preference, in any case.

What I put together works just fine, except for during heating and cooling cycles in the house.  In fact, when the unit was down on the work bench, it was working really well.  I put it on top of the stack last night before I went to bed to see what would happen.  It was ugly, as the HVAC vent is pretty close.  Maybe I should make up some longer jumpers and put it on the floor to see how much that stabilizes it.

Bob





>________________________________
> From: "GandalfG8 at aol.com" <GandalfG8 at aol.com>
>To: time-nuts at febo.com 
>Sent: Friday, January 31, 2014 3:18 PM
>Subject: Re: [time-nuts] EFC divider resistors
> 
>
>Is the op amp just a unity gain buffer or does it have any gain  setting 
>resistors that might be adjusted?  
>
>I'm just wondering if you could tailor the gain to reduce the swing rather  
>than require the oscillator to effectively require a larger swing.
>
>The 344310-T is likely to have come from a Trimble Nortel NTGS50AA, that  
>might even be the only source although I don't know for sure, and the EFC  
>swing on those runs from 3 to 6 volts, or at least that's the hunt range, so 
>the  344310-T needs to tune to 10MHz with an EFC somewhere  within that range 
>and that would have been a design or  selection restraint on the oscillator 
>when new.
>
>Older units are likely to be closer to the top of that range and I know  
>some have exceeded 6 volts whilst still seeming to be otherwise ok, so it's  
>probably a fair bet, with that oscillator for example, that you wouldn't  
>need to drop below three volts anyway.
>
>