[time-nuts] Re: Tbolt

[Andrew Kalman]

I'm a rank amateur on the time-nuts scale ... we did some replacements of
MTI OCXOs a few years ago, and folded all that info into a manual as we
built our own drop-in replacement OCXO modules for some XL Microwave and
SRS instruments.

It has some data on trim values for IsoTemp brand OCXOs, etc. that some
might find useful.

http://www.pumpkininc.com/space/manual/UM-20_Pumpkin_OCXO.pdf

----------------------------------
Andrew E. Kalman, Ph.D.


On Thu, Jul 22, 2021 at 9:37 AM Bob kb8tq <kb8tq at n1k.org> wrote:
>
>> Hi
>>
>> If you manually set the DAC with the commands LH nicely provides
>> (LH is the *best* thing about these TBolts !!!) you will find it runs from
>> -5 to +5V. The OCXO should tune linearly over that range ( all of mine
>> do).
>>
>> If you take a saw to the typical TBolt OCXO, you likely will find
>> a 10 MHz SC cut crystal in a single oven. The design changed over
>> the many years they were supplied. One date coded 1997 is not going
>> to be the same as one date coded 2005.
>>
>> On any OCXO, to see if it’s using a doubler, just hook up a spectrum
>> analyzer to the OCXO output. You *will* see the sub-harmonic. Much
>> quicker / easier than tearing the thing to pieces.
>>
>> Bob
>>
>> > On Jul 22, 2021, at 5:00 AM, Dave B via time-nuts <
>> time-nuts at lists.febo.com> wrote:
>> >
>> > On 22/07/2021 08:30, time-nuts-request at lists.febo.com wrote:
>> >> Message: 1
>> >> One more comment on the Vectron OCXO. My Tbolt shows a tuning voltage
>> of +0.4 Volt and has 3.6 Hz per Volt. Assuming the OCXO was sold to Trimble
>> with 0 V and my unit has at least 12 years on it (4380 days) aging is 3.29
>> E-11 per day. Not bad for an  OCXO.
>>
>>               Bert Kehren
>> >
>> > ------------------------------------------------------------------------
>> >
>> > Hi.
>> >
>> > According to Lady Heather, My T'bolt sits with it's DAC at about 0.2V
>>  I always wonder about that.
>> >
>> > From the above comment, is the DAC output (and VCXO input I guess)
>> bipolar, as in can range +- some amount from 0V?
>> >
>> > I've not seen any schematics for them, so in honesty haven't a clue
>> what it's likely range is, good bad or indifferent.
>> >
>> > I did email TVB direct about the possibility of sourcing another one or
>> two of them, but as he said (and I guessed) he was swamped with responses.
>> >
>> > I use mine mainly as a frequency reference, powered on 24/7
>> >
>> > Regards to All.
>> >
>> > Dave G8KBV (In the UK as far as I can tell.)
>> >
>> >
>> > --
>> > Created on and sent from a Unix like PC running and using free and open
>> source software:
>> >
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