Monthly Archives: January 2012

Various electronics

I’ve been a bit lazy lately but now I started to do something useful again. I started building the housing for the input filter for one of the amplifier projects going on. I also found a big fan which is capable of moving 21 m3 of air each minute that they were going to throw away at work. So I took it and when I tested it would not run, so I took a guess and replaced the motor capacitor and now it runs just perfectly.

I also finished up the box for the LP-filter for 20m. I have almost run out of 7/16″ connectors (chassie females) so I will need to pick a couple from the 80m filter at SJ2W which did not work properly and install it on this box instead. I did some quick measurements and managed to get about -65dB harmonic attenuation on 10m and about 0.15dB insertion loss on 20m. I think I can tweak these values slightly more, maybe I can get down to 0.1dB insertion loss and I will be pleased with it.

SO2R shacks added to the website

I added a page on the website which does contain pictures of SO2R contest shacks around the world, I think all information regarding this should be on the page so check it out!

This is inspired by K8ND but since there are no updates since a long time back on his page, I decided to add it to this website and add lots of shacks.

High power 20m LP filter

The LP filter I built earlier for 200w was today built for high power instead. It was a real mess, its hard to bend these copper pipes to fine tune the things and after some problems with the network analyzer I managed to get something that looked pretty good, but it took me hours. It takes a long time to solder one of those coils to the copper, so that is what is the biggest problem and of course after you have un-soldered it the thing is really warm.

Anyway, I managed to get 0.1dB insertion loss and about -65dB notch BUT when I was fine tuning the notch I managed to break one of the 220pF capacitors, and of course I did not have anyone left. I had lots of 150pF and lots of 330pF but nothing between and I did not want to redo the layout and use some other values in parallel. So I ended up ordering 18 pcs of 220pF capacitors from an Ukrainian.

Here are some pictures, now I need to make one for 80m too. On 40m the current hybrid low pass filter works really well, but the one I did for 80m did not work well at all so I am gonna make a similar HP filter as the one previously made.

Some progress

Hello lads,

Not much interesting stuff has been happening lately. I have mostly been working on the openASC firmware, which does not bring much updates to the website. I have also done some non radio related work at the station, however most time right now will be spent in the lab. I am making in input for the 4-1000A amplifier and will continue to work on the automation of it, so some updates of that will come in the soon future. When that is done I will start working on the 2x4CX1500B amplifier again.

RF-choke for the 80m 4-SQ

So now I promise to start updating the web page again.