Over the holidays, I picked up a second hand outernet kit to play around with. The kit consists of an sdr dongle, a low noise amplifier, and an L-band patch antenna and can be purchased new from https://outernet.is. What is outernet? Well, outernet is a filecasting service that beams community submitted and curated content from three Inmarsat satellites. Its sort of like a very slow off-grid news feed. The three satellites are:

The bitx module now has its own enclosure: A star wars lunch box! I didn’t change much about my original setup. I ditched the s meter and added a manual usb/lsb switch to the front panel. The red knob is the power/volume pot. There is a headphone jack under the switch and the rotary encoder on the right. On the rear panel, I added the antenna jack, a dc jack that supplies the 12 volts to power the module, and an optional set of binding posts to supply up to 25 volts for the power amplifier.

I finally put the universal qrp transmitter in its own enclosure. I cut down the board to fit inside an altoids sized tin. The actual tin came from a cheap arduino kit that I picked up on discount during the final days of radio shack. The circuit diagram for the transmitter can be found here. I made a small change from my original design. I remove the 60pf trimmer cap and the 47pf ceramic cap from the collector of the 2N2222 and added an old variable cap for tuning.

I added an arduino/SI5351 vfo that I had previously made for a dc receiver to my new bitx40 module. I tweaked the arduino code to add the offset, and added a low pass filter to the output of the SI5351. On the bitx board, I desoldered a leg of the L4 coil and plugged the output of the SI5351 to the DDS pins and it worked perfectly. Here is the code that I used for the vfo.

My bitx40 module from hfsigs.com finally arrived on Friday after a 23 day wait. USPS left a ‘We missed you’ note even though my wife was home and I had to go pick it up from the post office, but I finally have it. The package was slightly damaged during its journey from India to the US. It was a little crushed, but the board survived. The heatsink on the IRF510 was bent, but I will be replacing it with a larger heat sink to accommodate 24 volts for more output.

I ran across some code for turning a raspberry pi into a wspr transmitter with nothing but the GPIO pins (and a filter). Here is the code repository. I loaded up a raspberry pi with raspbian lite and compiled the WsprryPi code. From there, it was just a matter of adding a filter between the GPIO pins and the antenna. I fired up the software and let it transmit for about a half hour or so and here is the result.