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Author Topic: Easysats from shack - what's needed?  (Read 35000 times)
KQ6EA
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« Reply #45 on: April 10, 2013, 02:48:45 PM »

One tip on using coax seal.....put down a layer of good quality (Scotch 33 or  33+) BEFORE you use the coax seal.

When you have to take the connections apart (and someday you will...), you'll thank yourself for using the tape.

I quit using that goop years ago. Now I use these 3M self-fusing silicone cable boots. They're tubular, and you slide them over the cable before you mate the connector to the antenna, preamp, whatever. After the connectors are tightened, you pull the plastic "string" out of the back of the cable boot, and as it comes out, the boot collapses on, and seals, the connector.

Really neat things, but I can't find the data sheet I have, so I can't give you a link to the 3M website.

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N4UFO
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« Reply #46 on: April 10, 2013, 06:28:25 PM »

Those boots sound awesome! And yes, I learned the 'tape underneath' trick long ago... In fact I was just glad of it the other day when I took the feedlines off the MFJ two port switch to install my new Ameritron.  Grin  Also, if you ball up the goop and use it like a ball of cotton dabbing on the connector or other surface, you can get any remaining stuck goop to come right off... Some guys resort to some cleaner or mineral spirits, but isn't necessary.

73
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K0JEG
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« Reply #47 on: April 10, 2013, 07:51:20 PM »

As for #1... Thanks, Eric. You bring up something I hadn't thought of... stress points at the ends of the 'hang'. Being it is a short run, what if I simply wrap the coax from one end of the run to the other in a spiral of rope?

If you can lace the coax with a marline hitch (use figure C on the link below) it should work without causing problems, but over time it still might get loose in spots. I've used zip ties to attach .625 hardline to strand and they've held up for years (temporary fixes that are good enough sometimes become permanent). Given the cost of a bag of UV resistant zip ties I would think that and the dacron rope would be the cheapest/best way.

http://blog.makezine.com/2009/07/28/lost-knowledge-cable-lacing/

BTW: Off topic, but in my headends, cable lacing is most certainly NOT lost knowledge!
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N4UFO
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« Reply #48 on: April 11, 2013, 03:06:09 AM »

Eric... that looks so cool I think I'm going to hang the coax in the air, just to try this.  Cheesy  And since I built my own HW-101 as a Novice, I know what cable lacing is, just never knew what it was called! The wiring harness came pre-made, so I never had to do that... just the point-to-point "monkey-wiring" as it used to be called.

Question... assuming 2 runs of RG-213 and a rotor cable (4 or 6 conductor, I haven't decided yet) and a 23-24 foot stretch, how close together should I make the marline hitches? And the reason I haven't decided on the cable is, 'do I want to power the preamps on the feedline?' or 'do I want to run power up the rotor cable?' I was going to do it on the feedline, and may still, but I have to buy or build Bias Tees for the shack end. On the flip side, I'm not sure if running the rotor and preamp power wires together has any problems I have not foreseen yet. (Anyone?)

I think I also figured out that the way I am mounting the tripod, when it is tipped over to the ground, I will not be required to unhitch the cable from either end. BUT, I have to test this theory with a rope and a pole, because the math is more than I want to calculate.  Grin


By the way, while I am posting... does anyone have any recommendations about whether to choose a 22.5 degree or a 30 degree tilt to my antennas? I'm leaning towards 30 degrees, based on the observations of one ham (on Youtube) who is/was using an IOio antenna like I am considering.

Thanks guys, great stuff! This is why I enjoy venturing into new aspects of the hobby... you learn stuff!
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KQ6EA
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« Reply #49 on: April 11, 2013, 12:01:38 PM »

GO, Kevin!

The difference in elevation between 30* and 22.5* is probably insignificant UNLESS you're running antennas with a LOT of gain, where they tend to be pretty "pointy".

Stop and think.....If the beamwidth of the antenna is 30*, a few degrees in pointing error doesn't have much of an effect.

I'm not sure if you'll be using the "Cheap Yagis", so I can't answer the beamwidth vs elevation question, but you should be able to figure it out. You can always experiment a bit to see what works best for you, with your antennas.

Power-up-the-coax is quite common, but I've never heard of anybody running their preamp power up the rotor cable, unless they have more conductors in the cable than they need for rotor control.

I *was* running it up the coax, supplied by my FT-847, BUT, I blew the transistor on the 2 Meter side by not checking the 2 Meter bandpass filter I have to see if the center coax conductor was grounded.

It was.......

So now I just run some of the red/black 'paired' cable (looks like red/black zip cord) to the DC connector on the preamp.
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N4UFO
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« Reply #50 on: April 11, 2013, 05:22:38 PM »

Well, I'm planning on building an IOio antenna... making it out of PVC and large gauge copper wire. I originally had a choice of using a 60 degree elbow and end mount the antenna (giving it a 30 degree tilt) or use a 22.5 degree elbow and a tee. I took an exploratory trip to Home Depot today to see what parts were available in what size and made a lot of notes; I still have to figure exactly what to do, but likely I'll go with a 22.5 and a tee.

I've seen one IOio constructed where the UHF and VHF sections were built 90 degrees off each other. (the VHF horizontal and the UHF vertical) I am assuming this was done to minimize interference from one band to the other. I may try this... unless somebody gives me a good reason not to. (Again... anyone?) Well, to answer my own question, wouldn't be able to do much terrestrial weak signal with the UHF vertical... but with only 10 watts, I think my best advantage is to use the separation to help duplex reception.  Anyway, I would assume the bandwidth is fairly broad in both the horizontal and vertical direction, no matter which way it is mounted. The biggest advantage for me with this antenna is 'small & cheap'... and for some reason it just looks cool.

You'd think your rig would have some sort of protection to prevent that... I had a SW receiver once, even if you shorted across the antenna at the antenna connector, it didn't hurt anything. But in my case, it's fool with a tee or run power up the rotor cable. And yes, I will have extra conductors. The radio shop near here has several 1000 foot rolls of 5 conductor cable, which know one buys anymore so they sell it CHEAPER than 4 conductor... and I'm buying a 3 conductor rotor.  Grin  Normally you give the ground on the rotor two conductors... and if they preamp and it are compatible, I may let them share the ground.

In addition to the Home Dept list of 'lego parts' to design my antenna, I have made up my lists of 'needs' in the way of connectors and such... most I have found sources for; just a matter of purchasing them when I get the money. I got the lawn mowed this afternoon in advance of rain/storms tonight and marked off the spot for the base of my antenna tripod and proceeded to obliterate the grass in a 6.5' by 3' rectangular box on the ground. Tomorrow when the ground is soft, I will go back out and do my best to shave it flat. Then it's a matter of getting the railroad ties, cutting 1.5' cross pieces off the ends of each and setting them in place.

OH... I DID the geometry and trigonometry calculations today after a bit of measurement. If I did it right (my wife the math teacher says I did) I will have around 3 feet of slack in the feedlines when the tripod is tipped over to the ground. So I can secure the house corner end and not worry about raising and lowering. That'll be nice.  Smiley
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KQ6EA
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« Reply #51 on: April 11, 2013, 05:32:36 PM »

I'm not familiar with that antenna, but I'll give it a look.

Mounting them at 90* to each other is a good idea, as it will help (some) with desense on 70 cm.

Even though my antennas are about 8' apart on the cross-boom, I still mounted each of them at 45* to the cross-boom, so they wind up being at 90* to each other.

And the tip about using an inexpensive duplexer as a "Mode J" filter also helps. I'm using a Comet CF-416, but the next time I put the station together, I'm going to try the PAR Electronics filter I bought a few months ago.

Desense can be very annoying, and I've taken some pains to minimize it on my setup!

Jim
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N4UFO
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« Reply #52 on: April 14, 2013, 07:35:06 AM »

I've used/tried/bought most of the others out there, and SatPC32 really does do it all, and do it correctly.

And when it comes to "pretty, but broken" vs "not-quite-so-pretty but 100% functional", I'll take functional every time!

I started looking at tracking programs last night for the first time... I didn't download any, just looked at screen shots. I wonder if you would elaborate on your comment... In my case, I will have no computer control on either my rigs or my rotor, so for me, is anything about these other programs really "broken"?

For someone like me that is being 'screen dependent' for information, I found SatPC32 to be lacking... it doesn't show a track, just an arrow. Clearly it was designed for anyone using auto-tracking. And I read some ham's comments last week complaining to someone else about people "lazily" adjusting their doppler due to adjusting it manually... Geez, have sat ops gotten that picky? 10-12 years ago, it was understood that the other guy might be a little off frequency. And in the case of RS-12/13 in Mode K, it was 'adjust RX' anyway... I can't imagine that everybody on the birds is computer controlled and ops expect that much... or is it that some of the ops are just 'that bad' at multitasking and letting it get way off. If that's the case, I might understand his comment.

Actually, other than lack of a full screen display, I don't see a need for anything more than the N2YO website. If I could figure out how to make that display bigger, I'd be fine. (computer screen is not on hamdesk, but rather 90 degrees to the right) I am looking at Satscape. Since mostly what I need is the ability to turn, glance and know if I need to shift the rotor. Which, has brought up another debate for me... I have a choice of a regular old TV rotor control with the standard dial to turn, OR, I can get another push button controller like I have for HF. With the push button controller, I set each button 30 degrees apart around the compass. When I want to turn the beam, I just push the right button. In the case of satellites, every time the Azimuth on the screen passes certain numbers, I just push another button. It would be easy because the buttons would all be in order, just either forwards or backwards but not random. The other nice thing about this controller is the ability to 'train it'; you teach it how far the 360 rotation of the antenna is and it remembers that and adjusts it's timer. With some cheap rotors they can be 10-15 degrees off in a 360 degree rotation. (Google U-106 if you want to see the controller.)

yet another of the many debates and decisions to be weighed through to get back on the birds...  Cheesy

73 all, Kevin, N4UFO
« Last Edit: April 14, 2013, 07:59:14 AM by N4UFO » Logged
KQ6EA
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« Reply #53 on: April 14, 2013, 09:37:35 AM »

SatPC32 *will* display the ground track; it's turned off by default.

To enable it, go to the options box in the upper left corner of the display, and double click on the "G". This will show the ground track as a series of dots. I think the reason it's default is 'off' is that if you're tracking multiple satellites, the map will get covered with footprints and ground tracks pretty fast, making it hard to tell what's what.

You can make the display as big as you want by grabbing the frame of the display window and "stretching" it to as big as you want.

As far as adjusting for Doppler, there's a good article called "The One True Rule For Doppler Tuning", and it's available here:

http://www.amsat.org/amsat/features/one_true_rule.html

If all you need at this point is a graphical display so you have a rough idea of where to point, and when, then probably anything that strikes your fancy will work. Just keep in mind that you need to know your position, and the clock in your PC MUST be within a few seconds of the actual time. The LEO birds move pretty fast, and being 10 seconds off can make you lose the pass.
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N4UFO
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« Reply #54 on: April 26, 2013, 07:54:50 PM »

I just thought I would give an update on my sat station progress...

This afternoon my neighbor took me to get a 9' tripod and by 10pm I had the 14' mast pounded into it (extremely tight fit) and the whole thing bolted down to it's wooden 'railroad tie' base. I also picked up an Antennacraft TV rotor and some rotor cable, but it's going to be rainy next few days, so I won't get to do much more than play with it in the house probably. I picked out the rotor that was cheapest as well as the one with the type of knob on it that you can tell which way you are pointing it by 'feel'.

The antennas themselves are built... the mount is built except for gluing the two foot mast to the 'joining section'. I want to make sure that is the length of mast I will be happy with first. I have the Ramsey UHF preamp kit and the RF switch kit boards built, but not tested. (I haven't bought a 2m preamp yet.) I have the 2m coax connection mounted and glued together. (The cable from the antennas has a male BNC, the coax from the shack PL-259s; this mates them together.) When the preamp is done, it and the 2m connection (or later, the 2m preamp) will mount into the joining section and come off at an angle. (This will help with creating the 'rotating loop'.) The power wires for the preamp(s) will come down the center of the mast and run into the rotor housing where it will splice to two conductors of the rotor cable, which will supply power from the shack.

Basically, I need to finish the antenna, run the feedlines & rotor cable through the floor, solder on connectors, wrap the cables up with rope to be suspended over to the tripod and then mount the rotor and antennas on the pole. I have a 2m FM radio hooked up to use if my 2m all mode isn't repaired in time. Haven't heard anything from the repair guy yet... but he is usually very reasonable on cost, so I don't plan to rush him.  Smiley

I'm not going to guess on a time for completion as there are many other things going on around here this time of year (XYL is a school teacher)... but I am hoping to get finished up fairly soon. I'll try to post some pics of my progress on my QRZ page in a day or so... but it was a little too dark to take a picture of the tripod by the headlights of my SUV.  I didn't get started until after dinner and ran out of daylight, but I really wanted to get the tripod up, so with the rain coming working in the yard by flashlight/driving lights was not out of the question. Grin

I'll keep you posted... 73 for now.

Kevin
« Last Edit: April 26, 2013, 08:21:23 PM by N4UFO » Logged
N4UFO
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« Reply #55 on: May 04, 2013, 02:34:23 AM »

Further update... I have the preamp built and installed, the antennas are finished and up, connectors are soldered on, the feedlines & cable are run through the floor, my 2m all mode rig is back & hooked up and I'm just about done except for stringing the cable/coax through the air. (XYL held them up so I could mow under them yesterday.)  Grin  I also need to situate the cables on the mast a little better, the turning loops look a little weird at the moment.

I was still working on the hamdesk, running power wires and such, but I tried listening to a couple birds early yesterday morning. I heard the AO-7 2m beacon while the bird was out over the middle Atlantic... elevation must have been around 5 degrees. The next pass was over the eastern seaboard and I heard my own signal and called CQ but no one else was on. Then I tried a couple of VO-52 passes, but got disappointing results. On one pass, I would tune to what I thought was my signal, but it sounded more like the beacon. Then when I let up on the code key, it would disappear. In other words, anytime I transmitted on UHF, I would hear the beacon in the middle of the passband instead of my own signal. I don't know if I am experiencing some weird intermod in my own rigs/setup or something I was doing through the bird, but it had me scratching my head. Then the next pass, I heard two strong stations talking to each other, but I couldn't find my signal at all... I don't know if they might have been swamping the bird a little or I have a problem on my end. I was only transmitting with 8-10 watts on UHF to my 7 element yagi. But I don't know the characteristics of these birds yet... more experimentation needed.  Cheesy

As for SO-50... I tried to listen to a pass, I think the day before, on my UHF rig and it was very difficult to hear. (As far as I can tell the preamp is working.) I have read that the stock IC-451A is a bit deaf and a mod is recommended to swap out the front end transistor. I have ordered one (only $3 but 2.5 - 5 weeks shipping time) and plan on trying that, but in the meantime I may experiment using my little Baofeng HT both with it's handheld CJU antenna and hooked up to the yagi. I used about 2 feet of RG-58 to run from the yagi feedpoint to the preamp. I needed something small and very flexible to go INSIDE the PVC. I know that some guys have noticed a difference between a CJU antenna mounted directly to their HT and same antenna with a short jumper cable. I hope that short run of RG-58 isn't causing me problems. Like I say, I HEARD the bird and made out a call or two, it just wasn't enough to work anyone. Could have been the pass, could have been tumbling (handheld antennas can be turned) or maybe the new FET in the radio will make the difference. Only time and experimentation will tell.

Any suggestions/comments on the issues I am experiencing are most welcome. Otherwise, just wanted to post my thanks for all the help and encouragement from the forums here in getting me motivated and back on the sats. First post to 'antennas in the air' only took a little over 5 weeks.  Wink


73 all,

Kevin N4UFO
« Last Edit: May 04, 2013, 02:40:56 AM by N4UFO » Logged
N4UFO
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« Reply #56 on: May 04, 2013, 04:36:17 PM »

A long day of struggle and a steep learning curve, but I have worked a first QSO on AO-7, FO-29 and lastly, after three passes, VO-52! I need to figure out what is wrong with my preamp, I need an adapter so I can plug headphones into my 2m rig, but mostly I need some sleep!!! (Been up since the wee hours this morning)  And next sunny day I will try to get the feedlines strung up and get some better photos on my QRZ page.

To quote a campy 70s TV show character: I love it when a plan comes together!!!  (And on 'May the Fourth/Force be with you' day!) Cheesy

73 all, mission accomplished with this thread

Kevin, N4UFO
sat operator  Cool
« Last Edit: May 04, 2013, 04:40:49 PM by N4UFO » Logged
N4UFO
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« Reply #57 on: May 04, 2013, 07:18:28 PM »

and lastly, after three passes, VO-52!

Curses, Batman! Not in the log... I'll get you yet VO-52!

Oh, well... gives me more to strive for.  Smiley
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KQ6EA
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« Reply #58 on: May 05, 2013, 10:36:47 AM »

Keep at it, Kevin!

You're  making good progress, and learning a lot.

And that's what counts!

73, Jim
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N4UFO
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« Reply #59 on: May 05, 2013, 04:31:41 PM »

Thanks, Jim. Well, I found an adapter for my headphones, I got some sleep and I figured out there may be nothing wrong with my preamp... it's my radio.  Shocked

I got on for a late pass of SO-50 last night. It was going to be practically overhead, so I got out my HT and hooked up the little CJU antenna. I could hear the satellite on the HT, but my radio... heard almost nothing.  I even worked CO6CBF listening on the HT. I had just enough time to unhook the antenna from the radio and hook it up to the HT... I could still hear CO6CBF working others even though the bird was down to about 15 degrees. I couldn't really tell if the preamp was helping much, maybe I'll check that on another pass using the HT. Hard to tell without an S meter though.

Anyway, I have ordered a transistor for the RF amp in my radio's front end. Maybe not the best transistor I could use, but it's one known to work and has about the same impedance characteristics as the old one... therefore no required tweaking. (BF981 in place of a 3SK48) I don't have a good stable signal source to do any tweaking, but if I locate one, I may try that as well. I'm hoping that it will be enough improvement to make the difference. I was able to hear FO-29 enough to make a QSO... barely. THEN I can fret over preamp improvements.

If anyone has any experience with the Icom IC-451A, especially on receive, I would welcome any advice.


No satellite today though... R&R and some TV with the family.

73, Kevin
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