[time-nuts] Opening an Isotemp OCXO

Tom Miller tmiller11147 at verizon.net
Fri Oct 28 12:41:02 EDT 2016

When I have an unknown OCXO, I put a scope on the output and connect a bench 
power supply to the DC inputs. I bring up the voltage until the RF out hits 
a stable level. That is where the internal regulator starts regulating. Then 
set it to the nearest normal power supply voltage, +5, +12, +15, +24, +28 

Some OCXOs will have separate inputs for the oscillator and the oven. 
Example- an HP OCXO has a +15 regulated input that is switched for the 
oscillator and a +24 volt input for the oven that is on always. I usually 
try the same voltage as the oscillator first and watch the current as the 
oven warms up. If it takes too long to heat up, try a little higher voltage.

Some units have a separate ground return for the oscillator and oven so you 
need to watch that.

Good luck and thanks for the report.


----- Original Message ----- 
From: "Peter Reilley" <preilley_454 at comcast.net>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Friday, October 28, 2016 12:09 PM
Subject: Re: [time-nuts] Opening an Isotemp OCXO

> The only document that I could find said 12 volt.
> Pete.
> On 10/28/2016 11:49 AM, Poul-Henning Kamp wrote:
>> --------
>> In message <10a3ea7d-37f0-51bc-2470-35645d767bbd at comcast.net>, Peter 
>> Reilley writes:
>>> The chip is run off 12 volts so it must be CMOS.
>> Or the OCXO is not a 12V model ?
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