[time-nuts] thunderbolt fault
warrensjmail-one at yahoo.com
Fri Feb 26 23:59:25 UTC 2010
Yes, I Did that, The +5 and -12 has NO effect on freq or operation of the
unit except for really far out voltages.
I tested mine with the -12 from -2 to -15 and could see no effect in the
The -12 is used for the RS232 and the -Dac out so If you don't need the neg
Dac out voltage or neg RS232 Drive, then it can pretty much be anything.
But It should be kept in -7 to -13 range, and common sense means there
should be little noise on it so it does not couple into other things. BUT
the circuit it's self does not care what the supply is at or what is used.
The +12 on the other hand, Needs to be stable and quiet with no ripple.
I found using a +15 volt supply feeding a 12V three terminal will heat
slinked regulator a good way to go to keep ALL the ripple out of the +12V
Has anybody actually measured the supply sensitivity on the -12 volt line to
see weather a 5 volt change makes any noticeable difference in the output
frequency? The power on -12 is very low, so there should be negligible
thermal impact from a change.
On Feb 26, 2010, at 4:52 PM, George Dubovsky wrote:
> The -12 can be anything from -7 to -12V and it will work. The units that
> were removed from Grayson or Andrew equipment had a zener diode changed on
> the Thunderbolt (by Trimble) that kept the power alarm from being invoked
> low values of this voltage.
> geo - n4ua
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