[time-nuts] Fury Interface Board: 5MHz needed?

[SAIDJACK at aol.com]

In a message dated 11/7/2007 14:04:04 Pacific Standard Time,  
bruce.griffiths at xtra.co.nz writes:

>However for an OCXO using a high thermal gain oven controller  (E1938A)
>or a double oven (OSA B8607) such effects may be significant  if a single
>ground pin is used.



Hi Bruce,
 
on our 230 single-oven version of Fury the effect is negligible as you  
state. However on the 270 Double-Oven option it can become significant much like  
on an E1938A.
 
One simple solution is to use two transformer-isolated power supplies, one  
12V one for Fury, and one for the OCXO heater. No ground current can flow due 
to  the transformer isolation.
 
As long as the EFC control ground is connected as close to the Oven  
enclosure as possible there should be no negative effect on the system since no  
current can flow through the EFC SMA cable.
 
BTW: I also did some microvolt measurements on the OCXO Euro-can used on  
Fury, and I am happy to say that I cannot detect any voltage drop whatsoever on  
the OCXO case itself.
 
So it should be safe to solder the SMA coax cable center pin to the EFC pin  
of the OCXO, and the SMA cable ground shield to the case next to the EFC pin 
(as  long as the OCXO is not overheated by the soldering itself).
 
bye,
Said



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