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

[Ed Palmer]

Measure the wattage used by the heater at 24V and room temperature.  
This is what's required to keep the oven at the proper temperature.  
Lower the voltage to 20V and see if the heater draws the same wattage.  
As a second check, measure the current drawn at 20V at startup and then 
after warmup.  The difference tells you how much headroom you've got 
until the heater runs full on.

Ed

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 
>