[time-nuts] Thunderbolt Power Supply Question

Bob Camp lists at rtty.us
Mon Apr 26 13:00:09 EDT 2010


I'd say those are all pretty safe guesses with any modern OCXO. The drop out
on the internal regulator is likely to be well below anything we would put
on the +12 supply. 

The Trimble spec on the TBolt shows a +/- 10% tolerance on the +12V supply.
>From that I'd assume you could run the unit pretty much forever at 10.800
volts on the input. 


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Arthur Dent
Sent: Monday, April 26, 2010 12:36 PM
To: time-nuts at febo.com
Subject: [time-nuts] Thunderbolt Power Supply Question

The +12VDC supply (internal to the sealed oscillator) supplies both the oven
and the oscillator circuits. I think you'll find that internally this +12VDC
goes to the heater circuit as well as through a regulator to the oscillator
which is running on something like +7VDC. This is speculation at this point
but a number of similar type oscillators I've checked are set up this way
and even have a temperature compensated regulated reference voltage out of
about +7VDC to feed a pot or EFC circuit. For instance the HP 10811 has an
internal +5.7VDC regulated supply for the oscillator circuit

One crude way to check is to take a removed 10Mhz oscillator Trimble
oscillator and power it from a bench supply at +12 and let it stabilize.
Then reduce the supply voltage slowly and see where the output level and/or
frequency start to change. If you see no change until you've reduced the
voltage a few volts then the oscillator has an
 internal regulator for the oscillator circuit.    

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