Category Archives: Electronics - Page 30

Antenna switch system refurbished

Posted by sm2wmv on August 9, 2011 Comments Off

I have been working hard on the switching system the last few days. As mentioned earlier I was tired of how it looked and decided to change the mounting of the power splitters and try to get the control lines more organized. I am very pleased with the result. I used some cable ladders that I had gotten donated by SM3WMU which made it easier to handle the quite large amount of cables.

I’ve just briefly configured one openASC box and that works on all bands except 10m. I think I have some problem in the power splitter for that band, will investigate more tomorrow. I will now be able to use 10, 15, 20 and 40m on all four radios and with addition of 2 more power splitters for 80/160 I will be able to route those bands to all radios as well. Right now they are only on radio 1 and 2.

I’ve been thinking a long time about making it possible to unhook the 2×60 leaded control lines between the driver cards in the basement to the antenna switches located out in the barn. This is to make it pretty much impossible for close by lightning to ruin any of the driver electronics. Because even though I have transient protection I don’t fully trust it to 100% There is no safer way than just disconnecting everything. So I sat down and pealed and soldered a total of 240 leads, which was later installed. So I peeled a total of 480+ cables, a real pain.

Now I will also install some cable terminals that was donated by SG3P which has got the possibility to break the connection between the poles. That will be installed to the rotator cables so that everything to the house is unhooked, except the beverages. But for those I’ve gotten some GDTs to add as protection against surges.

Here are some pictures,

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Cleaing up the antenna switching

Posted by sm2wmv on August 5, 2011 1 comment

Today I first did work some on making it possible to use the fireplace in the basement again. Its half done, so I will try to finish it up tomorrow.

SM2LIY did move the 2 half squares for 30m to another position and has put the cables into the antenna switch room. A 6×1 box has been mounted so that we can hook up WARC antennas and route them to the main antenna switch system, so that no manual switching will be needed and the amplifiers can be used on them.

SM2XLL said yesterday that we should mount the stairs up to the switch room again since it has been removed since two years back. So today he showed up and we mounted the stairs again and also brought me some tape he bought in town. Its funny how a job which has been put on hold for 2 years gets done in 20 minutes, why not just do it at once?

I decided to do something I have been thinking of for a while since its been raining today, and that was to redo all the antenna switching so that its more tidy with cable ladders and proper accessories to mount cables easily. I also added the 2nd 6×2 switch which makes it possible for us to have four radios hooked up so that they can access all antennas plus I added a power splitter for 10m. Its only half finished though, I hope to finish it all up tomorrow except the power splitters for 80/160m which still need to be built. Do you have any 7/16″ females for chassie mounting which you don’t use? Then I need some of them to finish up the switch system.

Now me and SM2LIY will try the sauna since we now have the SM0W hinges mounted and ST0R in the log on the low bands 🙂

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Antenna switch progress

Posted by sm2wmv on June 25, 2011 Comments Off

This weekend they promised rain at SJ2W so I decided to stay in Luleå instead. Spend some more time with my girlfriend but also get some work done on the electronics. Earlier this week HA1AG guided me a bit through dissembling the FT1000MP MKV which had stopped delivering any output power. After checking the voltages etc to the finals which looked OK I started going backwards to see where the RF signal disappear and it did just before the finals. So I started measuring the bias voltage of the amp stage and it showed that the inductor in series with the bias was burned. So after changing it the radio worked again and HA1AG guided me through some of the tuning process along with the tech reference of the MP. Thanks to Zoli that helped me an convinced me to try to fix it myself before sending it to him. So instead of paying a lot in shipping it ended up costing me about 5 euro including of the inductor shipping.

Today I built another powersplitter, this one is intended to be used on 10m now when we hopefully soon get the 10m yagi up in the 60m tower. This time I put a fan on the device since we noticed that the 20m unit got quite warm in the WPX CW contest. So now when there is no radio activity I will plug the air holes and have the 15w heater inside each box to keep away moisture and during the contests we remove that and start the fans. So I will need to modify all the boxes which are currently at SJ2W as well. I also built a 6×2 switch which will make it possible for us to route four radios to any of the antennas, up to 18 different antenna systems (3 on each band). I have however run out of 7/16″ connectors so until I get hold of some more the switching system can’t be completed. This is because each band need to have a powersplitter even if we just have one antenna on the band. This is because of the A/B output on the splitbox, making it possible to route the powersplitter to either 6×2 #1 or 6×2 #2.

I am not very pleased with how the 6×2 turned out. The mounting plate for the connectors/board is fine but the casing wasn’t very nice. I couldn’t fit it in the milling machine so I had to bend it by hand which is always a mess, at least when not taking it slow and careful. I don’t like to spend too much time on making these things look perfect, I try to make the visible things in the shack look perfect, this kind of things is fine just as long as they work.

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Notch filter built and isolators made

Posted by sm2wmv on May 26, 2011 1 comment

I’ve done some work in the lab again. We’ve been seeing some QRM on 10m from 20m, so I decided to built another notch filter. I am very happy with the result, about -86dB notch and around 0.01dB insertion loss on 20m. I also spent some time in the lathe making some isolators for the 40m verticals for the 4SQ.

I really recommend these notch filters. They work great and are very easy to build. I start with making the stubs a bit too long. Then I cut them until I have the notch at the correct place. After that its a matter of decreasing the insertion loss, so I adjust the L until I get rid of the C from the stubs, giving a perfect 50 ohm match.