[time-nuts] Typical EFC frequency response (bandwidth) of a OCXO

SAIDJACK at aol.com SAIDJACK at aol.com
Mon Dec 18 15:00:42 EST 2006


Hi Bob,
 
thanks for the specs!!
 
For some reason this unit is slightly different though in it's specs:
 
It only uses +24V, no negative input provided by the Wavecrest PS. If you  
are right, the -5.2V is only applied to the output to bias  it, which is not 
needed. The -5.2V pin is left floating, only  +24V and the GND pin are connected 
in the Wavecrest DTS units (I have three  different DTS Models, all are the 
same).
 
Also, it's output is 100MHz, not 50MHz, maybe they multiply 2x?
 
I will fire it up again, and measure it's pull-range and jitter with my  
SIA-3000 Wavecrest analyzer, will try both EFC and mechanical tuning. Last time  I 
measured it, it had about 3ps jitter RMS.
 
Do you know what voltage range is safe to apply to the EFC pin (which was  
not used inside the analyzer)?
 
The phase noise seems great, considering that this is a 100MHz output!  using 
the typical formula for phase noise multiplication 20log(f1/f2) this means  
an equivalent phase noise at 10MHz of:
 
Equivalent Phase Noise (at 10MHz):
-145 @ 100
-160 @ 1k
-165 @  10k
-170 @ 50k

Thanks again!
Said
 
Said,

The 7 pin header is as follows: (starting from gap - going  CW)
1 -5.2 V (see comment below)
2, 3 case ground
4 +24V (6 W max at  turn-on)
5 probably NC - but may be reference supply output
6 probably NC  - but may be electronic frequency control in
7 may be NC - but could be EFC  return, in which case would be case ground

There is no EFC required by  the spec - but in some cases, a small
range EFC is included to facilitate  phase noise testing.

The output is specified as 1Vp-p into 50 ohms biased  to -2V - I
suspect that biasing is internal - and the only purpose of the  -5.2V
on pin 1 is to provide the negative bias.

Temperature spec is  +/- 10 ppb for 0 to 50C

aging: 3 ppm/yr

AVAR:  5E-11/sec

Phase noise:
-125 @ 100
-140 @ 1k
-145 @ 10k
-150 @  50k

The crystal is 50 MHz - there is a -40 dBc sub-harmonic  spec.

That unit shipped in March 1996.  If you get a chance, let me  know
what the frequency adjustment range is - I wonder how well it  really
aged. (Ideally, it would have been ~ centered when it was  shipped)

Bob




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