[time-nuts] Leakage, tinySA

[Dana Whitlow]

Another data point:  My newly-received TinySA has a big birdie at 10 MHz,
which is a
disappointment since I had hoped to use the unit as a sniffer to track down
leaks in my
10 MHz distribution system.  This birdie in the TinySA persists even when
nothing is
connected to the input and does not vary in amplitude when I move around
the house,
or with time while I'm sitting still with the unit.

I, too, received no manual.

Dana


On Sat, Jan 16, 2021 at 5:28 AM Hal Murray <hmurray at megapathdsl.net> wrote:

>
> My tinySA arrived a  few days ago.  I'm happy.
>
> It comes in a nice box with an antenna that extends to a foot, a USB
> charging
> cable (mini, not micro) and a couple of cables.
>
> It doesn't come with a manual.  I haven't found a manual online.  Their
> web
> site is pretty good, but sometimes I like a document organized to be read
> by
> turning pages rather than following links.
>
> The minimum receive bandwidth is 3.1 kHz.
>
> The specs say the lower frequency limit is 100 kHz but the UI doesn't
> enforce
> that.
>
> My strongest signal is at 30 MHz.  It's -60 to -80 dBm as I wave it
> around.
> At 100 kHz bandwidth, the noise floor is -110 dBm.  The 30 MHz blip is
> clean
> enough to see the shape of the receive bandwidth filter.  (I'm assuming
> the
> raw signal is much narrower than 3 kHz.)
>
> I haven't figured out where it is coming from.  At first, I thought it was
> coming from low power do-it-yourself PCs.
>   https://www.mini-box.com/
> If I get near them, lots of spurs near 30 MHz come up out of the noise.
> But
> powering them off doesn't change the 30 MHz.
>
> The 30 MHz is clean.  I'm guessing it's the 3rd harmonic of 10 MHz.  I
> only
> have a few of them, but I don't like turning them off.  Or maybe the 2nd
> harmonic from the Lucent boxes.  ??
>
> The 10 MHz is stronger near coax carrying 10 MHz and next to a Z3801A.
> I'll
> have to try some good cables.  Anybody have a favorite source?  Is there a
> magic word?  Do I have to specify the type of coax?
>
> I have lots of Gigabit Ethernet.  I have a blob at 125 MHz, and spurs at
> 120
> MHz and 130 MHz.  120 has a little brother 18 kHz higher.
>
> The normal power up mode scans 0 to 350 MHz with enough attenuation so
> that
> most of my signals are lost in the noise.  Sometimes it comes up without
> the
> attenuation.  Then I can see all sorts of stuff.  The biggest ones are at
> 240
> and 288 MHz.
>
> I think there is a mode for overlaying displays.  I haven't investigated.
>
>
> Their web page has links to software to talk to it over the USB cable.  I
> haven't investigated.  Plugging in the USB cable adds lots of cruft.  The
> software would be unusable unless you are looking at a strong signal or at
> something in a hole that the cruft misses.  It might work if you can
> freeze
> the display, then plug in the USB cable to capture it.
>
>
>
> --
> These are my opinions.  I hate spam.
>
>
>
>
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