Hi Jerry
My scope isn't up to 600 MHz either. I have an RF Explorer handheld
spectrum analyser but that samples the spectrum in a similar way to the
nano. Consequently its unlikely to be measuring 600 MHz from the nano at
the same time the nano was generating 600MHz. I may have a look by setting
the nano to CW mode but there's no guarantee that it works exactly the same
way as when measuring.
My two nanos have very different firmware. The semi-bad one has 2 trace
antenna analyser firmware dating from about April I think. The better nano
has 4 trace vna firmware that I think is August.
I haven't tried 800MHz firmware on the semi-bad one for two reasons. The
spikes aren't a problem andthey board in unmarked. There are two connection
points in the right place but given the lack of need there seems no point
in risking zapping it if those turn out to be unrelated to programming.
Mike
On Mon, 26 Aug 2019, 00:16 Jerry Gaffke via Groups.Io, <jgaffke=
[email protected]> wrote:
Regarding that 600mhz spike:
Would be interesting for somebody to look at the si5351 output clock with
a scope
on a unit with that 600mhz spike, see if anything weird happens when
scanning through 600mhz.
Does the spike goes away when the 800mhz firmware is used, or does it just
shift down in frequency?
Is this the same firmware as shown in the SA shot of post 1084, so we know
for sure
it isn't using the second harmonic?
Does the clone without the 600mhz spike have the same firmware as the one
that does?
The desired signals out of clk0 and clk1 of the si5351 are always 5khz
apart.
Could be weird if clk0 at 300.000mhz is using the fundamental
but clk1 at 300.005mhz is using the harmonic.
Unfortunately, I have no nanoVNA (yet) or a scope suitable for anything
beyond 100mhz.
Jerry
