Category Archives: openASC - Page 2

New SO2R position

I’ve been upgrading the SO2R position at SJ2W with the addition of a Elecraft K3 and an MK2R+. I’ve been busy making cables with filters built into the D-SUB connectors for the MK2R+ since I think it lacks a bit filtering. I need to finish up the cables for the K3 and need to think abit of how to do it so I can change between remote and local operation without changing any cables. I’ve listened a bit on the radio and it seem to be OK, we will see after the first contest what I think of it.

Various stuff has happened lately

SM0W, SA0AZT and SM0SHG came up to spend the weekend at the lab at work building antenna switches and I finished up the openASC-boxes for SK0UX. It was a lot of fun and we got lots of stuff done. They still have quite a bit of work to do but they got with them the openASC boxes as well, so now there are three stations in Sweden using the openASC system, SK0UX, SJ2W and SK3W.

It also seems like I am claimed #1 Europe on 20m SSB in WPX SSB which is a lot of fun!

I also did some tests to test if the theoretic Q-value of the PI-filters we use in amplifiers correspond to measurements done with the VNA. It did not match at all, I got the values 4 times higher when having Q-value of 12 on the VNA compared to the theories. However I need to do more thinking and testing on this to figure out why. Maybe somebody can explain? I used the -3dB bandwidth to calculate the Q-value.

I also spent time cutting metal for the power supply for the amplifier project. I’ve collected some material at work which would have been thrown out and used it for the amp. I also bought some wheels that will be mounted to the amp which limits the weight of it to 400kg, but I should have quite some margin 🙂

More work on the shack

I took a few days off work to get down to SJ2W and try to prepare it for the contests. I had some plans to maybe do ARRL CW next weekend and I have not yet decided if I will do it or not. Right now I don’t really feel motivated but we will see, if not I will do it part time remotely or if the girlfriend wants to come here next weekend I might go down with her.

These days I have almost gotten position for radio 1 and 2 (also SO2R position) running with some small things left to do. I have also plans to get the IC-7400 (Pos 4) up and running so that SM2LIY can listen to the beverages. However the neighbor has cut down trees so half of them are broken and there is a lot of snow, so fixing them is out of the question. Positive thing is that that piece of the forest wont be worked in for 25 years…

I also made it possible to turn on and off the electronics in the basement, so that we can reboot everything if needed remotely. The openASC system seem to be quite stable, but a few times this winter SM2XJP has had to go here to the station to reboot it. Now we can do that remotely so he should not need to go here *knock on wood*.

I am pretty happy with the result, its a huge improvement but still a bit left to do. I am gonna try to save some money to get another radio for position 3 or 4 so hopefully we’ll have 3xFT1000 MKV in the future, which would be really nice since it would also be a spare rig when doing SO2R contests. But first, the summer projects need to be paid 🙂

PowerMeter electronics

I milled some circuit boards at work and smuggled in a few of my own designs as well. A few boards which are ULN2003A driver cards, a couple of ethernet module boards for the openASC box. I also designed a few peak-hold circuits which I plan to test with the PowerMeters. I have a problem that the new 16-bit A/D converter is too slow so the time between the FWD and REF sample is too long and the SWR calculation does not get accurate. And since the sampling time is too slow I can not do any proper filter either except a very slow one. So I am going to try using an LF398 chip so that I can hold both channels for enough time, that I can get a couple of samples and do the calculations. I guess we will see tomorrow if it works or not 🙂