[time-nuts] Pins of ERC Precision Crystal Oscillator EROS-800-NTL-5 OCXO

Bob Camp kb8tq at n1k.org
Sun Jun 14 15:26:33 UTC 2015


Best guess is that the 4 pins are:


An ohm meter is your friend in this case.

Ground should be shorted to the case. 
Output should be DC blocked (as in > 1 meg ohm)
EFC should be something like 100K or so to ground
Power should have a fairly big cap on it, the ohm meter will go up in resistance slowly. 

In some cases the output has an attenuator (pad) on it. That will give you something like
< 300 ohms (but not a short) to ground. The EFC might be any impedance from 10K on up.
If your ohm meter will read capacitance, that’s a great way to spot the input capacitor on the
power pin. The EFC may have a bypass, but the power pin should have a much larger one.  

Once you have that worked out, check your results:

Apply power through a 1K ohm resistor. It should come up to a a few volts (< 8V). Don’t
leave it in this condition for long. You are simply trying to make sure you have EFC 
and power straight. If you apply +12 to the EFC through 1K, it will go up to roughly 
12V.  The same is true applying power through 1K to a DC blocked output pin. 

Now apply +12 to the power pin with a current limited supply. It should pull less than 1A. 
If it does, leave it on power and see if there is an output. If it’s got an output, you have 
things worked out correctly. If it has no output then either you have the pins wrong or the unit
is defective. 

Good Luck! This is not a prefect way to do it, but it works in about 90% of the cases. It’s fairly
safe in this case. You already know that the power supply is +12V.


> On Jun 14, 2015, at 5:41 AM, Mod Mix <modmix at t-online.de> wrote:
> Hi,
> got an ERC Precision Crystal Oscillator EROS-800-NTL-5 OCXO 9.9000000 MHz +12V RF (ebay item no. 140779678375).
> Can not find any data sheet to see which of the four pins is used for what, though.
> Any help would be much appreciated.
> Ulli
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