Här kan ni ladda ner presentationen som PDF.

Anyway, I showed a video tour of SJ2W during this ham meeting and I have published it on youtube. Currently it is in Swedish but I have plans to make a dubbed version in English.

Now I need to order some connectors and switches, so that I can finish up the maneuver boxes and start programming it. I will mount it in a 19″ rack box which will also contain the transfer relay and dummy load which will be used if the “wrong” radio transmits at the wrong time.

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Stay tuned…

I also added the in-band QSX electronics to the panel, which will hopefully this summer make us able to work in-band QSOs for real. I also got a couple of transistors from a friend at work (from mini-circuits) that I will use to build a 25dB preamp to be used to compensate for the cable loss. We are going to put up a vertical about 400m from the house using RG-59 as coax as a start to test how well it works on 20-10m. We will later extend the system using a small loop with the NULL towards our TX antennas. More information on this when I am putting the system together.

I also built a couple of power splitters. Or actually one of them is for 160m and does not contain the option to power split, its a regular 2×1 switch but with an A/B output making it possible to route it to both 6×2 switches, which means to any of the four operating positions. The other box is for 10m to replace the one at SJ2W which has got some funny problem which I have not been able to find. So I will replace it and see if the problem goes away, if so I will fix that splitter and make a new UN-UN for it with 6 windings so its optimal for 80m. I use 4 windings on 10m. I put the 7/16″ connectors in the lathe to make them fit into the PCBs. The connectors were donated by SG3P, thanks Gunnar! He has probably donated 90% of all 7/16″ chassis female connectors at SJ2W. I did order a few from China, very cheap so we will see the quality if they are good enough to be used at the station.

I also removed some BNC-connectors from old research projects that I will use on the in-band QSX electronics.

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Another problem is that since SK3W is primarily a M/M station, transmission will occur on 10m at the same time as for example 160m. Since this will result in any reflected power getting into the antennas on 160m from 10m will be shown as 24dB higher, thus if for example 1 watt is inserted into the pickup on 160m from 10m this will result in the 160m meter showing 250w of reflected power, which is quite a big error in the measurement and will for sure trigger a high VSWR reading. So to avoid this I very quickly designed a few 2-pole bandpass filters in Elsie which were just optimized to give lots of attenuation higher in frequency and insertion loss was not an important factor. It took a couple of hours to make the filters and the result was superb when we calibrated the units. Even when transmitting with 100w in the reflected direction through the couplers they as most indicated 0.1w in the 160m pickup.

We did not build any BPF for 10m since I felt this was not needed. Only measurement error will be from harmonics which should be at such a low signal level that the measurement error will be very low.

After calibrating the units Gunnar seemed to be very happy and hopefully it will work well at SK3W. I think he will be very happy for the high VSWR protection feature in openASC, a step of making the stations safe for “The Tord”.

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More to come…

The ringing sound is from the gears, hopefully it will go away after I put some grease on them. Everything isn’t perfectly centered so I don’t want to put much tension on them.

It feels good, now I need to clean my desk at work so I have some room to put the stuff up so I can write the firmware for it. Later I will extend the system by measuring grid current, anode voltage, anode current etc. The amplifier has got built in grid protection so I don’t need to worry about that.

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I also did more work on the amplifier project. I mounted 2 pcs of small relay boards which will be used to switch the input filtering plus also the relays that switch the output PI-network of the amplifier. I found this to be the easiest way to solve the issue of switching 12/24v relays since the amplifier control board had ULN2003A drivers to drive these small 12v relays. I also soldered lots of cables, so now the control panel is hooked up to the micro controller and soon its time to actually start writing the code, not that much too do on the electronics. I need to add another relay board to be used to switch ON/OFF the amplifier, toggle HV etc. plus I will need to hook up the potentiometers used to position the capacitors of the PI-tank to the control board.

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