[time-nuts] Re: 10 MHz TCXO periodically jumping 20 mHz up and down

[Bob kb8tq]

Hi

If it’s a sub $1 device, it’s pretty much guaranteed that it has digital 
“stuff” inside it. That circuitry will generate blips and pops totally
independent of any attempt it makes at compensation. If it “wakes 
up” this or that digital sub section every 107.34 seconds, you get 
an internal current spike. Spike hits grounding on the board ( or
the supply) and the output moves. 

There are dozens of other possibilities. Just like the one above, all
of them require a knowledge of what’s inside the part. Taking a 
hammer to it would be the first step ( = remove the lid :) ). Getting
a full schematic and the specs on the chips inside would be a somewhat
deeper dive. Dumping the programming information on top of all that
( = you have the layout of the PCB, the schematic, the parts list and
the specs on the parts) would top off the “need to know” details. 

Bob

> On Feb 18, 2022, at 6:52 AM, Erik Kaashoek <erik at kaashoek.com> wrote:
> 
> Hi Magnus,
> Tom also replied to my question and suggested a 107.34 seconds interval related to dithering with a 1e7/2^30 interval
> Unfortunately the datasheet is rather short (sub $1 device) and does not provide any hints to being a digital implementation.
> Thanks to all for helping!
> Erik.
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