build of the Si570 Controller and Frequency Generator Kit #2

The first step towards completing my January 2010 project was to construct the Si570 Controller and Frequency Generator Kit #2 by K5BCQ. This fairly simple kit, which is composed of mostly surface mount technology (SMT) parts, will generate a square-wave signal from the Silicon Labs Si570 oscillator, has a LCD display, and a rotary/push-button encoder.

Despite my best efforts to botch the assembly and initialization of the device, I successfully completed it over the weekend. Partly due to me breaking one of the rules of kit-building (i.e., no building kits when you are sleepy or tired), I soldered the V+ and ground from the power supply to the output locations. During check out, the unit wouldn’t power up. A quick email to Kees K5BCQ asked me to check the voltage on the regulator–which led to my realization that the V+ and ground weren’t connected to the regulator. <sigh> Lucky for me, the location of a few capacitors kept me from frying any ICs. Once I connected the power to the correct points, and performed the initialization steps (holding down the push-button while applying power), everything is working as expected.

The Si570 comes programmed with its initial frequency from Silicon Labs. I requested 10 MHz initial frequencies. The initial frequency of the Si570 is set in the menu of the kit in menu item 000. While 10,000,000 Hz should be fairly accurate, I’d like to measure the exact output at the indicated frequency to make sure that it is not off by a few hertz in either direction. The accuracy of the start-up frequency of the Si570 in the menu item affects the frequencies generated using the controller, so this is key to its operation.

The kit is flexible in the voltage required for its operation. I’m thinking about adding a 5V regulator from the main power jack and feeding the display/generator rather than having to drill another hole for a separate power supply for the device. Using a wire jumper (rather than a 1/4W resistor) near the voltage regulator, allows for the use of power less than 11V.

In addition to the printed instructions provided with the kit, I followed the instructions on Clifton Laboratories’ site which were very helpful. Thanks for providing this excellent resource, Jack!

Next–on to building the PSK-20!