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38. The Seti Markup Language (SML) 3/1/2001 to 2002-09-20 -
37. The Seti Markup Language (SML) 2002-09-20 to Present
36. Antenna Rotor Repair (2003-4-9 to 2003-4-18)
2003-4-11- The antenna has been disconnected from the rotor and lowered to the deck. The rotor is also remove from the pole and is now in my work shop for repairs. As I was dropping it, using only a small winch, I realized that I could never get it back up that way and had to come up with some better way of doing it. During a survey of the project I took some pictures of the LNA case and the effect of the sealing tape used to weather proof the type N connectors.
The LNA case looks a bit worse for ware after a year but is still water tight.
As you can see the tape does a good job of keeping moisture out of the type N connector.
This motor is rated at 24 volts but I run it at a higher voltage to generate the torque the antenna needs. At this point all the mechanical links have been remove, re-greased and re-installed. I don't see the problem with the system but other things need to be fixed so I still could run into the main problem. 2003/4/16 - I did find several thing wrong with the rotor and rotor control box. Mostly wires that weren't a large enough gauge to handle the current to the elevation motor and other odds and ends - small problems. I fixed all of those and found a couple of other wiring joints that didn't look to good so I reworked them as well. I also replaced a SN7406 (hex open collector inverter) in the LNA control system that had blown out. This made it so that the filter after the LNA was always in the circuit and could not be switched out. I put a 3 dB pad (fixed co-ax attenuator) between the LNA and the 25 dB line amplifier that I built (three MAR 6). I noticed that some noise spikes in the spectrum from the line amplifier that must have been self oscillation caused by a mismatch between the LNA and line amp. The co-ax SMA pad killed them and I really didn't need the full 25 dB anyway. 2003/4/18 - I had to construct a gin pole to rise the antenna and rotor back on the pole. The ladder in the next picture is 8' tall and the gin pole, behind the black 3" pipe that will hold the rotor and antenna, is about 15 foot. The gin pole itself is made from two 10 foot pieces of square steel tubing nested to 15 foot. The outside one is 2 1/2" the one inside it is 2 1/4". They are mounted to the side of the deck with 3 pieces of 1/2" threaded rod.
When you build a gin pole you must remember that it has to be a good bit higher than the assembly you want to lift. I miscalculated the overall height needed and was attempting to use only a single 10 foot tube. I couldn't raise the antenna high enough to place it on the rotor. I had to bring it all down again and go buy the second tube, climb up the pole and slide the second one inside the first. At one point I had a 10' piece of steel waving around over my head as I attempted to get them to slide together - damn near lost the whole thing down the hill.
If you ever have to build a thing like this don't skimp on the pulley. It has to be a strong 'V' shape that can keep the lifting cable in line and not get cut in half by the forces placed on it. The one I bought is a solid piece that can be directly lubricated with gear grease. There is nothing worse than having an antenna suspended in the air and the cable jam up in the pulley case. Its the critical part of a good gin pole - buy the best.
With the gin pole ready to work raising the 60 pound rotor was a piece of cake. Now the antenna itself. While the antenna is accessible I replaced all the galvanized hardware with stainless steel. The galvanized had started to rust and now is the time to replace it while I can. Ace Hardware made a tidy sum from all my purchases of 1/2 stainless fasteners.
I then hooked onto the antenna and raised it to the saw horse where it (and I) rested a bit. I drank a beer and admired my work so far.
Moving the antenna to the top of the rotor was quite a trick. It kept getting hung up on the rotor housing and had to be lowered down a bit and horsed around until it cleared and went up. I then dropped in the first two of four of 1/2" stainless steel bolts through the connection plate and it was secure. I then mounted the control box on the pole and got it all hooked up. Running the motors from the control box showed that everything was back in order. I nudged the rotor abound using the motors in the rotor to make the last fine movements. I then put in the last two 1/2" bolts into the connection plate. The antenna was back in its proper place.
To stow the gin pole I removed two of the three rods holding it to the side of the deck and then with the aid of the winch and pivoting on the third rod, lowered it to a stowed position. I sure hope I don't have to bring the antenna down again - Its just to much work. The RS-485 control line doesn't work for some reason but that's just electronics. I can fix that without a problem tomorrow. I also have to find a bag to cover the rotor head to keep it out of the weather. I usually use a 'stuff bag' that I get from the local sports shop. I cut the bottom out and fasten it around the rotor head with Velcro. I mark this task complete. Late Note: The reason the RS-485 control system didn't work was because I had remove a 3" piece of RS-485 cable that didn't appear to have a use. What is was doing was correcting a wire reversal I had somewhere else in the cable. The short piece was acting line a null modem cable that you might be familiar with. 35. Audio Connection Block Diagram (2003-05-03) If your like me not understanding a basic component of your task drives you nuts. That's the way it is with the audio components of the SETI Net. They work but how do they work. I have always found that a good block diagram will do wonders in helping to understand something but there is no such diagram for the sound system in Windows - until now. To get to the diagram I reverse engineered the behavior of the Microsoft volume control. Think its simple? Think again. Open the Volume control on you computer with a single click and you get the simple master volume control slider. Double click it and you get the Volume Control itself. If you double click it again the system puts a second volume control right on top of the first. This wasn't smart of Microsoft because, since it matches the first exactly and it appears that nothing has happened but there is a second one below. Select one and move one of them out a bit to see the other. Now select Options | Properties on one of them and then the Recording radio button then OK and you have the Recording Control.
If you work with them you can come up with the block diagram for your system as well but it should look a lot like mine.
The interesting things this shows are:
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