Very good to know! ?This is a strong indication that everyone with a Raduino emitting 1mhz has a broken 25mhz crystal. ?Goran had earlier reported 1mhz coming out of his Raduino Si5351 instead of 4.8mhz, and that he could not see 25mhz at the Si5351's crystal. ?I have found crystals in general to be relatively sensitive to high G shocks, such as when dropping a board one meter to a concrete floor.
When I get back to my bench in a few days, I'll try powering up the Raduino with that crystal disabled, see if the output of the Raduino goes to around 1mhz. ? Unless somebody else steals all the glory first. ?(Please do!) ? Probably ok to just short one side of that crystal to ground. ?The data sheet does not indicate which pin drives the crystal and which receives (both pins XA and XB are called out as "input"). ?So I'll short the pin that has the smaller 25mhz signal, that's almost certainly an Si5331 pin that is input only.
Jerry, KE7ER
On Tue, Mar 14, 2017 at 05:46 pm, Goran VE6GPO wrote:
I just tried that on Adafruit's 5351 module, and yes, you can see the 25 MHz. I was looking at the output of 5351 with one channel set to 10 MHz an triggering there. Output was 3.something Vpp. While doing that, probed both side of xtal with second channel, x10 probe, seeing 25 MHz of almost-sine wave, ~1 Vpp on one side of the xtal, ~700 mVpp on the other side. Output signal wasn't disturbed at all while doing this. Tried loading with x1, 25 MHz dropped to <300 mVpp, but output was still going on.
Cheers,
Goran VE6GPO
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