Tuesday, February 24, 2015

Calibrating the Si5351

Jason's library has a very good calibration procedure found by clicking on 'File\Examples\Etherkit-si535\si5351_calibration'
You will need some way of measuring frequency. Once done you will end up with a number that will replace the 0 in this statement:
si5351.set_correction(0);

Initialization now takes two arguments in the new library. Instead of just the crystal load capacitance - it now takes the crystal frequency as well.

 si5351.init(SI5351_CRYSTAL_LOAD_8PF, 0);

 A zero as the second parameter defaults to 25Mhz, as above.
 If you're using a 27Mhz crystal you could change it in the header file (si5351.h) or just put in 27000000.
Any and all comments are appreciated.

Tuesday, February 10, 2015

Sunday, February 8, 2015

KD1JV PFR-3 transmitter

I always wanted to try making making a cw transmitter like the one in KD1JV's PFR-3. It looks so simple. Steve uses the square wave comparator output of the AD9834 into an *74HC02 quad nand gate to buffer the output into 3 paralled BS170's. Since the Si5351 already puts out a square wave - why not? A quick test gave me 4 watts into a dummy load. I added a 40M LPF because I plan to lash this up with an already built CRX1 since it has some nice built-in conveniences, like TX/RX switching, muting and a nice twin-T sidetone oscillator.
Spectral plot of output.





Below is the finished product.

Receiver/Transmitter

Front Panel



Etherkit Si5351 breakout board
Close-up of transmitter
video

Sunday, February 1, 2015

Codebender Arduino IDE

Recently I came across this video from the Open Source Hardware group which describes a cloud based IDE (Integrated Development Environment) for Arduino. This may simplify things for some people who have had problems with setting up an Arduino Environment on their home computers. For me, it means keeping the code all in one place and the fact that I simply like it better than the Arduino IDE.



To add a new library in Codebender click on the codebender gear in the upper left corner of the page (if you are on the code page) or "Upload library" on the upper right if you are at the home page. The library must be zipped. If it is downloaded from NT7S Si5351 or Rotary it is already zipped for you. In that case, just drag them from your download folder onto the Codebender "Upload a personal library" pop up that occurs when you press the green button.
Codebender allows me to embed my sketch into my blog where you can have your way with it. If you have Codebender installed on your browser, you can compile and download to your Arduino from here. If you want just the LCD_VFO_Si5351_IF.ino file for the Arduino IDE  click here.