[time-nuts] FTS 1200
EWKehren at aol.com
EWKehren at aol.com
Fri Aug 10 10:46:24 UTC 2012
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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