I’ve been planning to build a tesla coil for a while now. I’ve even wound a secondary for it, but I haven’t gotten around to doing anything else with it yet. My end goal is to set up a spark gap tesla coil with some home made capacitors being driven by my zvs driver and a flyback transformer. Earlier this week, I saw this youtube video by Keystone Science demonstrating a very simple circuit that will drive a coil.

So I guess I’m going with a DDS vfo and bfo. I put together the most of the bfo from the schematic, but instead of using a crystal, I will pipe in the dds signal into the base of Q9. For the transformer, I did 8 trifilar turns of 28 gauge wire on an FT37-43 toroid.

I haven’t done much on the bitx in the last few days, but I did put in a 12 volt relay to do the transmit/receive switching. All I did was glue the relay upside down and solder a diode between the relay coil. Right now I just trigger it by touching that loose red wire on the right to one side of the relay coil. I played some audio from my phone through the audio amp and tested the switching and it is working as it should.

Last night I continued my work on the bitx 20 by adding the mic amp. I put it in next to the af amp. I also added some rails to the side of the board. One for 12 volts, one for transmit, and one for receive. I’ve got some sharpie markings between each section to try to keep things separate in case I need to troubleshoot anything later on. I soldered on an electret microphone and the amp appears to work correctly.

My experiment with digital modes on 40 meters was rather unsuccessful and I’d like to try my luck on 20 meters, but unfortunately, I don’t have a 20 meter transceiver. I’ve had fun with my bitx40, so why not try building a bitx20? I will try to log my entire build here. There may be some breaks while I order parts, but hopefully by the end, I will have a working bitx 20 meter transceiver.

Over the weekend I tried my hand at some digital modes with the bitx 40. I was really wanting to try out PSK31, but I couldn’t find any on 40 meters. I did run across plenty of RTTY though. First, I needed to get the bitx talking to the computer. I tried rigging it up to three different laptops, but I had no luck. I even built a board to split the TRRS connectors into separate line in and out jacks with full on audio transformers and everything, but I still couldn’t get it working correctly.