[time-nuts] FTS 1200

[EWKehren at aol.com]

Bjoern
Thank you for the link I am able to change the frequency 4 Hz from - 2Hz (  
0V)  to + 2 Hz (-12.2V) using pin 2. Reading the info that you got me  
probably explains the slot next to the connector, but I experience a much wider  
tuning range on pin 2 and John is right any positive voltage forward biases 
the  diode cutting off oscillation. Will do some testing.
Thanks again Bert 
 
 
In a message dated 8/10/2012 6:28:17 A.M. Eastern Daylight Time,  
bg at lysator.liu.se writes:

Bert,

Good that you got the EFC working!   But I  would be a bit suspicious of
needing -13V.

It seems from:
http://www.ece.gatech.edu/academic/courses/ece4007/08fall/ece4007l01/al4/dat
asheets/symmetricon_oscillator_instructionsheet.pdf

that  the default EFC configuration is (0 to +10)V with a range of 4e-7
(2Hz).  From the same document there are a lot of other EFC configurations,
but  none that goes outside of +-10V.

My 1200 has about 3.5Hz tuning range  on (0,10)V. Se attached jpg. I did
not check behavior on negative EFC  voltage.

--

Björn

> John,
>   that did the trick I can tune it with a negative voltage, minus 13   
gives
> me plus 2 Hz but this unit came out of a FTS 5000 and it had a  positive
> tuning voltage.
> Bert
>
>
> In a  message dated 8/9/2012 9:13:29 P.M. Eastern Daylight Time,
>  jmiles at pop.net writes:
>
>>  John
>> Oven did  reduce in current and I can not imagine that it would be   that
>> close with an overheated oven. At 0 V it is within .5 Hz of  what  they
> normally
>> are. Ground has no effect but  even 0.8 V on pin 2  stops oscillation
>
> That's a  suspicious-sounding voltage.  Are you  sure you're not
>  forward-biasing the varicap?  Maybe some of these  OCXOs were  specified
> for
> use with negative EFC voltage.
>
>  If so, then  driving the diode with a negative voltage should raise  the
> operating  frequency (which is what you  want.)
>
> -- john,  KE5FX
>  www.miles.io
>
>
>
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