First prototype for the receiver unit

Been a while since my last post. A lot has been going on with both antennas, electronics and other stuff!

Some days ago I got the big privilege to borrow a CNC router from my friend. It’s an old LPKF91S and I had no software nor cable to the computer. I had no idea of how it worked and what to do to get everything running. Luckily some of my friends had both worked with this exact machine and also with similar models though a bit more advanced. I found a schematic of the cable via the internet and the software part eventually worked out! Now I was ready to mill my first printed circuit board!

The first thing I did was to mill out a sample that came with the software, turned out really bad as I had no idea how to set the height of the drill. Three tries later and I got it working really good. I quickly ran to my main computer and started to put together the last parts needed in one of my schematics in Eagle to start milling. It turned out that I had to do a double sided board and that was at first no problem as I had double sided copper but after the top layer was done milling, I noticed that the software had no idea were to put the bottom layer. My first thought was that I had done something wrong in the Eagle files but it turns out it has something to do with the calibration in the software, I will look into that later.

So, I can print one sided circuit boards.. Let’s make one!

One of my biggest projects is the Diversity Receiver System. This system will decide the best receiver in a 8 receiver system for analog repeaters. The schematic for the part that will be placed in each receiver was almost done, so I added some extra components and then started with the layout of the board. Some hours later and it was finished. Now for some milling!

The milling almost went great the first time, I had to mill some parts of the board a second time to get it perfect. While this board could be better, I am very pleased with the results! The components where quite easy to solder on with flux and a good solder tip. Unfortunately I didn’t have all the components needed for this board to fire it up today but I will take a trip to Elfa on Friday and buy the rest plus some other useful stuff.

I have to give a big THANKS to Mikael Larsmark (SJ2W) who was kind enough to help me with both schematics, layouts and exports for the CNC machine when I had some trouble. He is the god of electronics in my eyes, check his page out for some awesome stuff!

2x13el 70cm DK7ZB Yagis

For some time ago, I built two 70cm yagis to be used in the NAC contests. These are 2 antennas with 13el each and a DK7ZB design. Each antenna has around ~14dBd gain and the two of them stacked should have ~15-16dBd gain including cable losses. This day had crazy winds and sometimes I really thought that the tower would break or at least that I would. But after some struggling and twisted ropes I got them up and mounted.

New tower section

It has been a long time since I last updated this blog but now I’ve had some time over to write new posts. My tower has now one more section and finally I can see over the trees! This makes a huge difference in contesting on high bands like VHF, UHF etc. The weather was good and no wind so it was pretty easy to go up with the skylift and attach the new section. Took about half a day.

Clearing tower for new section

Today I’ve done some work around the tower. I am going to put up a new section so all the cables had to be cleared from the tower. Really unwieldy cables to wind up! Maybe I’ll take down all the antennas and other stuff in the tower tomorrow. I also have to fix better guy lines as I am now using real guy lines on the first section but only blue rope at the second..

First prototype for the diversity system

The last week has been a lot of fun. I’ve finally “released” the first part of the diversity systems firmware and also built a prototype PCB for testing. This board controls the receiver and will be placed in each receiver in the system, a vital part that must work before anything else can be tested correctly.

While testing the board I realized that one of my filter designs didn’t work out as expected but I’ll look into that this weekend. This is just one part of the whole system but still fun to see that I’m making some progress after such a long  time.

For all of my firmwares in this system I’ve built a CLI (command line interface) to control all the AVR processors via the computer (usb). This makes everything so easy as I can make all calibrations and debugging etc. directly from the computer.