haburton's blog

In my first blog, I discussed getting my WSPR station receiver system working. In this installment, I'll describe the work I've done on a stand-alone WSPR transmitter.

Thanks to Andy G4JNT, I began working on the MJB stand-alone beacon controller designed by Johan Bodin SM6LKM. I implemented the schematic pretty much as shown. I had a small board with a RS-232 to TTL converter on it, a MAX236, so that's where I started. I wired in the PIC 16F628, the DDS-30 board from AmPRO and a hex-inverter for the I2C Clock, Data and Chip select lines. I wasn't sure I needed them, so I tried it both ways, but he definitely inverts the signals in his software so the inverter is necessary. I didn't have a 74HC14 that he recommended so I used a 74LS04 which worked fine. The pin-out is different but he didn't show it so that was an easy change.

I recently joined into the WSPR throng and wanted to share my experiences in making it all work. This was a very challenging project to me, harder than it should have been. I have been a ham for almost 30 years, I am an Electrical Engineer and have been an electronics hobbiest for over 50 years. However, in my older years, the ADD has really set in and I don't comprehend all I read as well as I should so most of the problems are my own and might not affect you at all.

To begin with, I downloaded the WSPR V1.11 software for my PC, installed it and connected my Sony ICFW-7600G Shortwave receiver through its earphone output to the microphone input of my PC. Tuning to 10.1402MHz proved very difficult. The Sony only has 1 kHz tuning digitally and a BFO knob for fine tuning. There is a USB/LSB switch, but it doesn't really give you good USB/LSB selection. The BFO is the thing. I don't own a regular ham receiver so the Sony was it.