[time-nuts] 5370B and 10544 OCXO

[SAIDJACK at aol.com]

No necessarily.
 
It could also mean the 5370B "likes" the output signal of the 10544 fed  
internally better than the other two, maybe due to a higher signal level or 
less  noise in the internal PLL bandwidth?
 
You could verify this by feeding in the 10544 into the front jack while the 
 10811 sits inside the unit itself, then reversing (switching) the two  
oscillators with each other and comparing results.
 
Theoretically the result of both measurements would be identical, except if 
 your 5370B somehow likes one over the other, possibly due to the way it  
multiplies the 10MHz up to 200MHz.
 
One oscillator may have a better noise spectrum in the loop bandwidth of  
that 20x multiplication PLL etc.
 
Your measurement is basically using the following: full noise bandwidth on  
the external "A" input, and possibly only limited noise bandwidth in the  
internal connection due to the internal 10MHz to 200MHz up-conversion PLL 
which  has a smaller noise bandwidth than the "A" input.
 
Hope that makes sense,
bye,
Said
 
 
In a message dated 5/4/2012 15:06:37 Pacific Daylight Time,  
iovane at inwind.it writes:

Recently  I bought for cheap a nice looking latest production but not 
working 
5370B.  It turned out to be missing the 10811, its power supply card, and 
the  
relay. I borrowed these parts from my 5370A, and the 5370B worked fine.  
For 
some reasons today I've been swapping OCXO's between various counters.  
What I 
noticed on the 5370B is a different behavior in the test made  feeding the 
time 
base output (rear panel) to the front panel input and the  counter set to 
frequency. As we know (already discussed here), the readout  in this 
condition 
is not 10 MHz (which would appear logical as the  oscillator measures 
itself), 
but something like 9,999,999,xyx, with xyz  varying continuously. Well, in 
my 
case, I noticed that:
-with the 10811  all of the three rightmost digits (xyz) were varying 
randomly;
-with a  Piezo Crystal clone, same result as with 10811;
-with a 10544, only the two  rightmost digits were varying.
I repeated the test several times.
This  would mean to me that the 10544 is less noisy, at least mine. Am I  
right?
Antonio I8IOV