[time-nuts] Supply voltages for the Efratom 105243 10MHz OCXO

[Bob Camp]

Hi

It's tough to know just how far off of 24 V they compensated the oven. It's unlikely that they have a pre-regulaor on the heater. As you drop the voltage, the oven gain will also decrease. It's safe to bet that it will work at 24 +/- 10%. Past that - who knows... At 20% low, the failure is unlikely to be catastrophic. The impact will simply be a degradation in the temperature stability. 

Bob


On Mar 20, 2011, at 4:24 AM, Mike Millen wrote:

> Many thanks to both of you.
> 
> Is it safe to assume that the oven has its own temperature control system?
> I ask, because I'd prefer to run it from  approx. 20v instead of 24v.
> 
> With a controller (& a room-temperature environment) I'm hoping that it would still be
> operating at its design temperature with a lower voltage.
> 
> Comments?
> 
> Mike
> 
> 
> Bob Camp wrote:
>> 
>> The board looks a lot like a pull from a Lucent base station. The
>> voltages would all make sense in that context. The unit swaps in for
>> an LPRO and the 15V would be easy enough to come up with. I'd bet
>> they ran both pins off of +24 though.
>> 
>> Bob
>> 
>> On Mar 19, 2011, at 5:20 PM, Arthur Dent wrote:
>> 
>>> The pinout shown is close. The oscillator supply voltage on the
>>> one I have in circuit is +15 @ low current. The Oven requires
>>> 24VDC @ .25A and this drops to under 100ma when the unit
>>> reaches operating temperature. There apparently is an internal
>>> regulator on the oscillator supply and if you watch the output
>>> level as you increase the oscillator supply voltage you will see
>>> it increase until you hit about 13.5VDC then it remains constant.
>>> This may mean that you could run the oscillator on either 15 or
>>> 24 volts but where I'm only guessing what's inside the case I'd
>>> stick with 15VDC to play it safe. The pin next to the output that
>>> goes through the on board  diode is apparently an oven o.k. signal
>>> that drops from 5VDC (cold) to around .8 when the oven reaches
>>> operating temperature in around 3 minutes. This probably could
>>> go to the base of a transistor with or gate input if you want to
>>> use it to drive an LED. 0-5DVC on the EFC pin changes the output
>>> by about 28Hz
>>> 
>>> -Arthur
> 
> 
> 
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