September 2007 - AMSAT-BB - mailman.amsat.org

Re: Running Rotors on A/C Inverters ?
by Reicher, James 24 Sep '07

24 Sep '07

I've had good results running my HD73 rotor, using a 300W inverter, purchased from a big-box store discounter, for about $40. I bought it initially to run a 13" TV with a built-in VCR in the car for my harmonics when on long trips. It uses a lot more wattage (140 watts) than the rotor does and I've never had an issue with it cutting out or blowing a fuse. 73 de N8AU, Jim in Raymore, MO Light travels faster than sound... This is why some people appear bright until you hear them speak. Date: Sun, 23 Sep 2007 14:24:23 -0500 From: "Rhett Duke" <rhettduke(a)gmail.com> Subject: [amsat-bb] Running Rotors on A/C Inverters ? To: amsat-bb(a)amsat.org Message-ID: <1ce2b74b0709231224p716e916bob520781d46a6044(a)mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1 Hello All, I have a old Alliance HD-73 azimuth rotor and a Kenpro KR-500 elevation rotor.At present time I cant set up at my home on a permanent basis but would like to run a setup on a spare utility trailer that I can work from in a field behind my house...problem is no A/C power.....I am curious what size a/c inverter would be recommended for this type of load......I'm currently taking the ARRL Analog Electronics course and am learning how to figure such things but I'm not comfortable making calculations for a real world situation that involves motors at this time. I am also aware that you have to be carefull with what "quality" of inverter you choose.....some of the cheaper units you buy at discount places are WAY overrated.....I'm looking for something thats a good VALUE....Thanks 73 KI4OVO AMSAT # 36579 -- I am always doing that which I can not do, in order that I may learn how to do it.

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FS: G3RUH Dish Mount and Feed Mounts
by Eric H Christensen 24 Sep '07

24 Sep '07

I have an extra set of dish mounts and feed mounts for a G3RUH 60cm dish if anyone wants them. I'll sell them for what it costs if you bought them directly from James anyone needs them. 73s, Eric W4OTN

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ISS PBBS upload
by Mineo Wakita 24 Sep '07

24 Sep '07

http://www.ne.jp/asahi/hamradio/je9pel/iss_aprs.htm de JE9PEL, Mineo Wakita

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Re: AO7 Info for kb2hsh
by Reicher, James 24 Sep '07

24 Sep '07

I've worked Mode A on AO7 with an 817 and had similar results. I added a 30 watt amplifier and it was enough. My suggestions are to add an amp and (if possible) upgrade your antenna to a yagi, at least 5 elements. BTW, I've got an RF Concepts RFC 2-23 available for sale... 2 watts in, 30 out, with built-in pre-amp. I don't have my 817 anymore so this is surplus to me. 73 de N8AU, Jim in Raymore, MO Light travels faster than sound... This is why some people appear bright until you hear them speak. Date: Thu, 13 Sep 2007 13:35:47 -0400 From: "tjjapha(a)earthlink.net" <tjjapha(a)earthlink.net> Subject: [amsat-bb] AO7 Info for kb2hsh To: amsat-bb(a)amsat.org Message-ID: <380-220079413173547221(a)earthlink.net> Content-Type: text/plain; charset=US-ASCII You may have hit the nail on the head. I don't do Mode A, but that's what I found on Mode B. 5watts just didn't hack it (small antennas at even a great portable QTH) on Mode B. That was uniformly the case for me at a number of QTHs. I added a 20 watt amp. and it works great. The 817 was used in all cases. Nobody says I'm too strong with the 20 watts! Good luck, Tony, N2U

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rotator brake release kills computer
by D. Craig Fox 23 Sep '07

23 Sep '07

Problem solved. went back to basics, ran a ground buss connecting the rotor control case, radio case and computer case, and voila' no more USB disconnect. sheesh, thanks all Craig N6RSX Amsat no. 36607 NOTICE: This communication may contain privileged or other confidential information. If you are not the intended recipient of this communication, or an employee or agent responsible for delivering this communication to the intended recipient, please advise the sender by reply email and immediately delete the message and any attachments without copying or disclosing the contents. Thank you.

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Re: Mounting antennas on a tower
by John Kopala 23 Sep '07

23 Sep '07

Eric, Here is another approach to the problem. 1. You need a rotor base plate that can be mounted at any level in the tower. Basically, it should rest on and be secured to the cross braces between the tower legs. 2. Next use a thrust bearing at the top of the tower. 3. Your mast needs to be heavy enough to withstand whatever winds you may encounter from storms when extended several feet beyond the top of the tower. At least half of the mast will remain in the tower. 4. The mast can be positioned vertically within the tower using a pulley at the top of the tower and a rope secured to the mast near the base. Helpers on the ground use the rope to raise and lower the mast while a person on the tower guides and secures the mast at the desired height using the thrust bearing. 5. You then attach the elevation rotor with its cross boom and antennas in as many steps as required to do so. 6. Using the rope to control the mast height, loosen the thrust bearing screws and raise the entire structure so that the satellite antennas have the necessary clearance above the HF beam. 7. Secure the thrust bearing screws and attach the HF beam. 8. Again raise the mast so that he HF antenna is at the desired height plus about 1 foot and secure it in place. 9. Attach the rotor base and rotor to the tower just below the base of the mast. 10. Lower the mast to the top of the rotor and secure it in place. That is how I set up my current HF installation. Rather than having a satellite setup on top, I have an Cushcraft R-7 vertical which extends another 22 feet above the top of the mast and is spaced about 5 feet above my triband beam. You can put anything up there you want. I was not thinking satellites when I set this up many years ago, so my satellite antennas are on a roof mount. I prefer center mounted antennas because I can mechanically balance the entire antenna system. I have balanced it front to back, side to side, and up and down. Basically I mount my antennas on a fiberglass cross boom and adjust the antenna positions (with coax attached) so that the whole setup is balanced front to back. Then I use another pipe and clamps to determine the rotor position so that the setup is balanced from side to side. Finally, I mount the heaviest antenna on the bottom side of the crossboom and the remaining antennas on the top side to further eliminate imbalance as the antennas rotate vertically. The idea is to minimize the stress on the rotor gears and bearings. Ideally, the rotor is not lifting or supporting any extra weight when it moves the antennas. The antenna structure could be moved with one finger if the rotor was not holding it in place. With end mounted antennas, the rotor brake and gears must support and lift the entire weight of the antennas every time the antenna elevation changes. I'll also send you a picture of my current satellite setup. This is NOT the ideal setup because the rotor is not mounted in a tower section and there is no lateral support above the rotor for the mast. But it does give you a look at a setup with center mounted antennas on a cross boom with an elevation rotor all mounted above a 6 meter beam. The satellite antennas do rotate a full 180 degrees of elevation and clear the 6 meter beam. The longest antenna is an old KLM 2 meter circular polarized antenna that is 12 feet in length. Note that with the cables attached, the balance points move somewhat toward the rear of the antennas. Also, note the preamps just below the azimuth rotor. And DON'T FORGET the preamps. John Kopala N7JK ----- Original Message ----- From: "Eric Christensen" <eric(a)christensenplace.us> To: "AMSAT-BB" <amsat-bb(a)amsat.org> Sent: Friday, September 21, 2007 7:03 PM Subject: [amsat-bb] Mounting antennas on a tower > I'm contemplating antennas and a tower at the new homestead and I have a > question. > > If I can figure out how to mount an elevation rotator at the top of a > pole and have the azimuth rotator rotating said pole from the tower > would I have any problems with putting a small HF tri-band beam on the > pole, below the elevation rotator, and then mount all my satellite > antennas to the elevation rotator's pole? Has anyone done a combination > like this? > > 73s, > Eric Christensen, W4OTN > AMSAT Area Coordinator - Southeastern Virginia USA > AMSAT Member 35360

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my rotator control killed my computer
by D. Craig Fox 23 Sep '07

23 Sep '07

Greetings all. Thanks for all of the great info in this BB which has allowed me to get my sat station up and running. Now I have an odd problem. Just got CAT working on SATPC32 and was ready to make some contacts until I pressed the "brake release" lever on my CDE (az) rotor control box. Instantly disconnects or turns off the computer port to which the TS2000 is connected thru a USB/serial cable, and causes any number of port error messages. This "brake release" lever must be pressed before the antenna may be turned. When the lever is pressed, there is always a loud hum from the box and rotor which suggests to me that a very strong magnetic field around the rotor cable (which runs near the USB/serial cable), or the control box, is responsible for the computer and port problem. One other twist. Everything works perfect on my laptop, but want the larger desktop display. Has anyone experienced this have an idea for a fix? Thanks all! Craig N6RSX Amsat no. 36607

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[amsat-bb] NOVA, Labjack and accutator utility working in XP in realtime
by ok1vaw＠volny.cz 23 Sep '07

23 Sep '07

Dear friends, Maybe this can help to somebody who is solving the problem of control of the antenna tracking as I was doing some time ago. On the beginning there was a wish to be able to work the satellites. I had a very old rotator with AC motor and pot (such as Kenpro, this was sold in Germany under the Conrad brand with name Commander around 1989), which works still well. Then I solved a problem to control the elevation. After refusing the possibility to buy and extra rotator for elevation due to the high cost and impossibility to be used in my conception, I have decided to use Accutator (Superjack). After the years of different hardware changes (PCs, Pascal to Delphi, Dos to XPs, A/D D/A card to Labjack U12) I have solution, which seems to work with DDE to Nova (NLSA) in the realtime. 1. A realtime utility tracks the DDE server of Nova and waits for a current change of elevation or azimuth. 2. The rotator pot for azimuth is measured by the Labjack (10bits resolution) and by use of simple relay circuits the PC by use of digital IO of Labjack controls the motor to right position. 3. The elevation control is much more sophisticated, because it must read the pulses of the reed contact of the Superjack in the realtime (about 5/sec) and recompute the pulse count for angle (quite non-linear complicated form). Although it is not so straightforward and fast (=terribly slow data reading due to using the XP about 100x lower) as it was in the DOS/Pascal environment, but it can be used and it works. 4. So after some development, there is a very rough (I like to have still the CRT type display by use of Wincrt unit for Delphi) program, which works with Nova in the realtime and tracks the sats. 5. If somebody wants to ask for some details,how it was done, I am ready to help. You can view my antenna farm on www.qsl.net/ok1vaw. Regards, Vojtech, OK1VAW. Sorry for my english.

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Running Rotors on A/C Inverters ?
by Rhett Duke 23 Sep '07

23 Sep '07

Hello All, I have a old Alliance HD-73 azimuth rotor and a Kenpro KR-500 elevation rotor.At present time I cant set up at my home on a permanent basis but would like to run a setup on a spare utility trailer that I can work from in a field behind my house...problem is no A/C power.....I am curious what size a/c inverter would be recommended for this type of load......I'm currently taking the ARRL Analog Electronics course and am learning how to figure such things but I'm not comfortable making calculations for a real world situation that involves motors at this time. I am also aware that you have to be carefull with what "quality" of inverter you choose.....some of the cheaper units you buy at discount places are WAY overrated.....I'm looking for something thats a good VALUE....Thanks 73 KI4OVO AMSAT # 36579 -- I am always doing that which I can not do, in order that I may learn how to do it.

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Mode-L/U takers at the East Coast of NA
by OZ1MY 23 Sep '07

23 Sep '07

Hi in the East part of North America, I am looking for one or more QSO partners on the East Coast. I have never made a QSO with someone on the other side of the pond in this mode :-( I am in Copenhagen, JO65fr. Mode-L/U works very good and I can work down to 3 degrees of elevation. 73 OZ1MY Ib

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