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

Hal Murray hmurray at megapathdsl.net
Wed Nov 7 14:23:45 EST 2007

[from two separate messages]

> Any ground loop error above about 10 - 50 microvolts would affect the
>  systems' accuracy on good double oven OCXO's.

> George for a single ground pin OXCO you might want to consider
> compensating  for the oven's internal ground bounce. The voltage drop
> caused by a normal  heater current is around 1/4 to 1/2mV for an MTI
> 260 oven.

I'm missing something.  MTI has been in this business for a while.  I'm 
assuming they aren't dumb.  Why are they still making (otherwise) very high 
quality parts with only a single ground pin?

I'm not picking on MTI.  They are just a handy example.  Many of the data 
sheets I've looked at have only one ground pin.

My first guess is that it's a backwards compatibility mess.  Ages ago 
somebody made a part with a single ground pin and somebody used it in some 
telco gear and everybody has been using the same footprint ever since.  If 
that's the case, I'd expect there would also be a variation with a second 
ground pin to get better performance.

How much better would their part be if they had a second ground pin?

Are they running temperature tests with the EFC pin open so they don't see 
any problem as the heater current changes?  (or something like that)

These are my opinions, not necessarily my employer's.  I hate spam.

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