Category Archives: Electronics - Page 29

Finished up the stackbox for the 40 stack

Posted by sm2wmv on October 6, 2011 Comments Off

Yesterday I had some time over at work, so I spent an hour mounting the 40m stackbox into a weatherproofed box which will be mounted between the top and lower Yagi in the 60m tower. The box contains a few W2W Russian vacuum relay and allows us to switch between both in phase and out of phase. With no voltage to the box the Top Yagi only is connected (because of the relays just being SPST) but through the L-match, so SWR will be a bit bad. The L match converts the 25 ohms we get when connecting the Yagis in parallel to the 50 ohms we wish to have to the radio. The capacitors are Russian doorknob 220pF capacitors. When I measured the box I pretty much a perfect match and about 3.04dB insertion loss measuring on one port, which means the insertion loss is 0.04dB to each antenna which is very little.

The thing left to do is to make a mount so that we can attach U-clamps to it which are attached to the tower legs. This will hopefully be done on Friday or Saturday morning, so we can get the box up the tower on Saturday or Sunday.

No real effort in SAC SSB this year, we don’t have the time for it. The tower work will probably take quite some time and after that we will start finishing up the 18m tower which we want to get up before the snow arrives, which can be any day now.

Here is the old picture gallery from when I built the box. Ignore the measurement values since those have been greatly improved now with a bit of tuning. I have a feeling too that the network analyzer during those pictures were not calibrated, because it seem to be a bit too much insertion loss.

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Control box for the amp conversion kit

Posted by sm2wmv on September 7, 2011 Comments Off

I’ve been building a bit more on that conversion “kit” for making one of our manual tuned amps automatic (in this case, an 4-1000A amp). The idea is that you already have all meters etc on the amp, grid current, anode current etc. So this box is just a way to tune the amp manually but then save the settings and they get loaded automatically when the box is switched from LOCAL to REMOTE mode by sending commands over the openASC bus. The C1/C2 PAD is to switch in extra C in the Pi-filter. As a first step the openASC box will send the band information and when the amp should be tuned, but later I will make an similar box as the openASC which will show grid current, anode current etc in the shack as well.

I am quite pleased with how the box came out, except the REMOTE ending up too close to the hole.

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openASC has got rotator support

Posted by sm2wmv on September 6, 2011 3 comments

I’ve done some coding on the openASC project. I took a KR-400 rotator home with me which SE2T gave me, which I earlier converted to be controlled with an openASC box. Now I’ve written the code to both rotate antennas with preset or manually. I also implemented so that one can configure a rotator board through the USB port of an openASC box. That way we don’t need to physically access the rotator board when configuring it. It seem to work well, both on rotators which are centered north and south. That is now indicated on the display, so that when we manually rotate antennas we have an indicator telling us if we should go over north or south.

Now I will need to build boards for all my rotators and put them in, hopefully I can have the openASC system controlling all rotators @SJ2W before CQWW CW, which means our 4-radio openASC positions are pretty much completed with full control of the whole station from each position.

I will need to write some support for rotators which we don’t control by pushing its buttons with a relay, but those rotators who have built in presets etc and can be communicated with through RS232. The openASC rotator board does support this, I just need to implement some communication protocols. Since I bought an alfa spid I assume that will be the first, but if I implement for example DCU-1 protocol, it should work with most rotators.

I’m also building a 4-SQ box for the 80m 4-SQ array, so that SM2NOG can get his COMTEK box back which I borrowed when the QTH was bought. I will post some pictures of that maybe tomorrow so stay tuned!

Some milling done

Posted by sm2wmv on September 2, 2011 Comments Off

Today I milled bigger holes in two type of gears which will be used to give a 2:1 ratio between a stepper motor and an 10-turn pot, which will give us an absolute position of the capacitors. This will be used to convert one of our manual tuned amps to an preset tuned one. Hopefully if I get this working before CQWW SSB it will solve our amplifier problem since I can use it on most bands thus freeing up the 4CX1500B amp to be used on the 2nd radio. The idea is that the double axle stepper motor will be put in “series” with the capacitor axle. So the idea is to tune the amp as usual, and when you have it at maximum output power we just press save and it saves the position for the current band and segment. That way the openASC box can inform the amp of which band its currently on and the amp will tune to that position. I will make a real maneuver box for it in the future, similar to the openASC but for amps. However this is a lot of work and will be built in the future, now I want to get the amp functional.

The 2x4CX1500B amp project will continue when the outdoor work at SJ2W has stopped because of snow, so hopefully I can finish that amp up this winter too.

The excavator will probably dig some holes at the QTH this weekend, stay tuned!