Adjustment Procedure - ONE EOSC10KV3 User Manual

5) Adjustment procedure.

First, verify that RV1 is at middle position (It's H2 trim). Then :
Connect one output to a real time spectrum analyser (sound-card and FFT analysis software like Arta),
or to an oscilloscope (you need to show amplitude change, choose fast FFT view with low bin count).
Turn RV3 slowly counter-clockwise until the amplitude start to increase.
As soon you see something on spectrum, let it increase to it's final value.
If the gain is sufficient , you must clearly see the low frequency damping loop with output voltage
converging to it's final value (That can take some time).
If not, continue to turn RV3 very slowly counter-clockwise to add a little more loop gain.
After the oscillator start to oscillate WITHOUT saturate (excessive loop gain), verify that you can change
the output ampitude using RV2 on the front panel.
If yes, you have closed the control loop right !
So now, with RV2 (at front) set the output level to desired value .
Then, verify by powering on,off and on again if the unit start OK again and reach the previous setted
output. If the oscillator do not restart, you need to increase a little the gain again.
OPTIONAL and only if you can read H2 level with accurate setup :
I noted that H2 level could be reduced using lowest loop gain of RV3.
So, you could try after to turn very slowly RV3 clockwise to reduce gain and see if it affect H2 level
(while maintaining output level of course).
SUMMARY OF IMPORTANT POINTS TO REMEMBER :
This is RV3 that control global gain loop (to start the oscillator), but NOT control the output amplitude.
If control loop gain is too big, the output saturate, if too low there is nothing on output.
Is there a short range where the oscillator work, with output settling to the adjusted amplitude (with
RV2).
After the oscillator start to oscillate WITHOUT saturate (excessive loop gain),
then we use RV2 on the front panel to set the output level to desired value.
NOTE :
Because of the very narrow adjustment gain band to make the oscillator working stable, it is
possible after a correct adjustment to have the oscillator not working properly after some time of no use
or when temperature gradient occur. Note that the operating voltage can also affect stability, it is
recommended to always supply the oscillator with same input voltage.
If this problem occur, it can be necessary to repeat the adjustment procedure.
If the oscillator work properly, you must have output voltage corresponding to your previous setting.
That's all !
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