Saturday, August 6, 2016

ADF4351 signal generator





Although I have a portable signal generator using the SI570 that can get to 200MHz I needed something that goes a bit higher. Looking on ebay I found some modules that cover 35 MHz to 4400MHz using the ADF4531 for 20GBP so I ordered one (auction 172152204149 by ayanhu81)






It took 4 weeks to arrive. The next question was how to control the module. An internet search revealed a design by F1CJN here  using an Arduino UNO and LCD shield with buttons from dfrobot.com, which I did not have. However I remembered in my collection I already had a similar LCD/Switch unit from adafruit This would need some code modification, time to remember how arduino's worked. It was not too hard as Adafruit provide the libraries and examples for this unit on their web site. The biggest issue was as my switch reading used SPI not the A/D converter of the original design it was much faster resulting in much keybouncing.  Some strategically placed delays stopped that issue.

I now have it working. Listening to the signal on 144MHz and 432MHz it sounds OK, if a little off frequency due to the cheap on board reference (6kHz low at 432.2MHz) but as the board has an external reference input that is not an issue. Next to take a look at the output spectrum, which is reputed not to be too good at lower frequency, then to put it in a box.

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1 comment:

  1. Looks interesting. Interesting enough that I have one ordered to play with for 1296 MHz. I've been playing with ASD9850's and the SI Labs synths but this one seems to be rather useful for 23 and 13Cms. 73 AL. GM1SXX

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