Hi,

I now have my WSPR transmitter working. I have had several requests for the schematics so I have included them. My output power is 1/4W but I suspect if you ran a higher gain output transistor with a better output matching network, you should get at least 1/2W and possibly more. Since the two stages of the PA are the same, you could also add a third with a lower value emitter resistor and get more power. Be careful though to use a higher rated output transistor. The 2N2222A that I use won't deliver much more without blowing up. I use mine with natural air convection and I do not use a heat sink but I think I should. I just don't have one.

If you have any questions on this, please don't hesitate to ask. Good luck,

Remove the _.txt from the filename and you can get all the remaining information to complete this magnificant product.

Harley
N5BFB
73's

06-18-09
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.

06-18-09
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.