[time-nuts] Datasheet for TeleQuarz 20TQG01?

[Bob kb8tq]

Hi

Regardless of who made it, OCXO’s often don’t do well after being knocked around. 
The process of puling them off pcb’s is stressful to the internals. The shock and vibration
in normal “junk box” storage can be an issue. As a result, the original performance data
may not be of much use. 

I’ve tested a lot (like hundreds) of surplus OCXO’s. Well under 10% of them met their original 
performance specs. That’s just for the stuff I can test in the basement, with better test systems, 
the total would be lower. 

Pinout wise, the ground pin *should* be easy to spot. Normally it’s bonded to the case. Once you 
have it identified, start looking at pinot diagrams for similar sized OCXO’s. It may fit a standard
pattern. That would give you a guess for the +12V pin.

Hook up with a supply set to about a 1.2A current limit. Apply 12V to the assumed supply and 
ground. The part probably pulls < 1A and almost certainly pulls < 1.5A. After 10 minutes on power
the current should start to cut back. If the case gets really hot (like you can’t touch it for the count
of 5) then something probably is wrong ….

Once you have it on power, a ’scope hopefully will spot the output pin. If it’s a sine wave, running
without a load may give you a pretty distorted output. 50 ohms is a good guess for the load.

The EFC pin should look like a high resistance on an ohm meter. It may or may not have a bias
on it when the device it powered. Feeding it 0 and 2.5V while watching the output on a frequency
counter should let you ID it. After running the device for a day or three, “tune” the EFC to whatever
voltage gives you 10 MHz. That’s the center voltage for what you have, regardless of what it
was when it left the factory ….

Lots of fun !!

Bob

> On Aug 22, 2020, at 8:34 AM, Paul Boven <p.boven at xs4all.nl> wrote:
> 
> Hi again,
> 
> Replying to myself:
> 
> More online searching has revealed that 20TQG01 is likely a date code (week 20 of year 2001, charge G?). The other identifiers printed on the OCXO are '7368' and 'EO10391410'.
> 
> On 8/22/20 11:56 AM, Paul Boven wrote:
>> Dear time nuts,
>> In my surplus drawer, I found an OCXO which I would like to use for a home-built GPSDO. The part in question is a 10 MHz, 12V OCXO, type 20TQG01. It came from a flea market, and looks to have been removed from a PCB. It's fairly large metal case (h = 2.5cm, w = 4cm, l = 5cm) and has 7 pins. According to the seller, it achieves 1.2 ppb (!).
>> Unfortunately, the Telequarz group no longer exists, and I've been unable to find anything resembling a datasheet. Any further information would be very welcome, especially pinout and performance parameters.
>> Regards, Paul Boven.
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