[time-nuts] MTI 260-0624-D OCXO

[wb6bnq]

Hi Mike,

There are three possibilities in play.

1. The pot does set the EFC range OR
2. It adjusts the oven temperature.
3. In either case the adjustment range may be small enough that your 
current equipment resolution may not be able to see the change.

If it were the EFC adjustment, I would think that should be see able.  
The oven set point circuitry may mask the pot change in that the pot's 
range may be just a small fraction of the total temperature adjustment.  
That is to say there may be fixed resistors in series with the pot that 
would have a bigger effect.  The fixed values set it to near the 
turnover point and the pot's small value may have just enough range to 
make it just past the turnover point.

My two cents,

Bill....WB6BNQ


timenut at metachaos.net wrote:

>I have just about finished trashing this OCXO. I was able to run it outside of
>its case, and I have repaired the case, but I was unable to reinstall it into
>the case because I have to patch it on both the top and bottom. I could,
>perhaps, put it into a larger case and might do that later. For now, I will
>keep it as a potential future resource. The SC crystal is worth that much -
>they aren't cheap and nothing wrong with that. Also, just the bottom circuit
>board has problems, possibly another bad unit could be used for parts.
>
>That leaves one final question. The suggestion that the POT adjusts the
>temperature set point for the crystal sounds very reasonable. It clearly does
>not significantly affect the frequency. At least, not in the range that would
>allow for tuning the output frequency.
>
>However, the POT is clearly designed to be adjusted AFTER everything is
>assembled because it is intended to be adjusted through the hole in the case.
>That assumes some sort of feedback. What feedback? What can it affect on the
>available five pins that would let you know when the temperature is set
>correctly? If it is not for setting the temperature, and not for setting the
>frequency, what is it for? Perhaps output voltage level? I would have to get
>it working again, but I could test that. Any ideas?
>
>
>Mike
>
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