Hi Jerry,
we might be on the wrong track here ... last night I quickly put together one of these G3UUR crystal test circuits. Put the 25 Meg xtal from Raduino, and I'm getting 25 MHz out (actually, 24.99459 MHz). Didn't have another 25 meg xtal to put in the Raduino, but tried 20 MHz that I had on hand, tried probing but don't see anything. Still getting same wrong frequencies at the output as without any crystal. Granted, I know that 5351 needs either 25 or 27 MHz crystal, and I'm not sure if 5351 would even consider working with some other values. Worth a try.
But, it's definitely not a Nano, because I have same results with Arduino Nano, Arduino Pro, Arduino Uno, and Freeduino, all from different sources. Well, chasing this problem was so fun that I sidetracked from BITX itself. Now, I'll just use Adafruit's 5351 and get back to BITX. I have no intentions to try to desolder Si5351 from the Raduino board ;)
Cheers,
Goran VE6GPO
On Wed, Mar 15, 2017 at 07:21 am, Jerry Gaffke wrote:
No. ?The 1mhz problem is not due to bad Nano firmware. ?Not a bad 5v or 3.3v rail. ?There's no way for a reference clock to go from Nano to Si5351, so it's nothing to do with the 125khz startup clock in the Nano. ?But there is evidence that the 25mhz crystal is not working.
In post /g/BITX20/message/23393?I gave three threads, the first of which included post ?/g/BITX20/message/23306?which points to these two older threads: ?/g/BITX20/message/21886?and /g/BITX20/message/22008?regarding Goran's issue. ?Goran was the first to see the 1mhz problem, and he thoroughly checked his board with a scope, reflashed the Nano, checked his 3.3v, and probed the 25mhz crystal. ?No source for the problem found, except that there was no signal at the 25mhz crystal pins, but it was felt that perhaps the scope probe was disturbing some sensitive nodes there. ?However, now in post?/g/BITX20/message/23400?Goran reports that he can see a 25mhz sine wave at both pins of the 25mhz crystal of his Adafruit Si5331 board. ?My conclusion is that Goran's problem with his Raduino board is most likely a broken 25mhz crystal, and that may be the issue with all Raduino's giving a 1mhz vfo at power up.
On Wed, Mar 15, 2017 at 01:11 am, John Backo wrote:
In other words, the Nano itself may be the source of the problem. It would seem to be at least likely, since the
25 MHz oscillator for the Si5351 chip is working.
?
?
Goran VE6GPO