Offical AMC 8 Transition Thread (was Sat. AMC-8)

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Nathaniel Steele
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Re: Offical AMC 8 Transition Thread (was Sat. AMC-8)

Post by Nathaniel Steele » Thu May 25, 2017 8:43 pm

looks like Ill be trying the first one again tomorrow, with the better spec-an. Now to see if I can find an old protractor....or there's always wal-mart...

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Re: Offical AMC 8 Transition Thread (was Sat. AMC-8)

Post by ChuckG » Thu May 25, 2017 9:25 pm

We used one of these

http://www.homedepot.com/p/Johnson-Magn ... /100161689

on the back side of one of those Comtech dishes. Worked just fine.

Spec An plots never looked like the printouts for us either, but the receivers locked and have good numbers.
<><><><><><><><><>
Chuck Gennaro
Central Wisconsin

ncradioeng
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Re: Offical AMC 8 Transition Thread (was Sat. AMC-8)

Post by ncradioeng » Fri May 26, 2017 2:33 pm

I posted this image awhile back - it's a sweep of the entire range of transponders on AMC-18 that has the providers' carriers (LNB output). If your polarization is close to where it should be, then you should be able to match this up and you will be on the correct satellite.
DSCF0377.JPG

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kkiddkkidd
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Re: Offical AMC 8 Transition Thread (was Sat. AMC-8)

Post by kkiddkkidd » Fri May 26, 2017 7:44 pm

Nathaniel Steele wrote:
Thu May 25, 2017 10:36 am

So, Does anyone know for a fact wether either of those dishes will or won't work or what my problem could be? Clearly I'm not as good as I thought at this....
These frigging things can may you question your self worth... And then it pops on and you wonder what was so hard about that.

There is really no such thing as a reasonably sized dish that "will not" see the carriers. Even an 8ft dish should be able to see the carriers but probably not well enough to be even marginally reliable as far as a receiver is concerned. IE, you should see the carriers but there won't be enough gain (or enough adjacent sat rejection) for the receivers to lock reliably. IF you are getting a ton of cross pol interference then that might be covering the desired carriers but I have never ran across that.

As someone else posted, set the elevation (and pol) as close as you can and then swing the dish while looking for the published carrier group plots. If you don't see them, lower the dish a degree and repeat, if you don't see the plots, Lower it another degree and try again, if still nothing, raise it back to the EL from which you started and then another degree more to get near the next bird above.

Don't trust any hardware point on the dish mount UNLESS you verified it to be true before leaving AMC8. I regularly find hardware that looks square or perpendicular to the dish face that is actually a number of degrees off of either. I built a fixture to lay across the dish face to hold a protractor but a string or straight board will work well.

Make sure that you have the skew twisted the right direction for your location. Dishpointer.com has a good description of this.

Make sure that you are looking at the the same center freq and span of the published plots. Before I saved the settings and trace info for each of the transponders, I more than once wasted time looking for a specific signature on the wrong freq/span.

Make sure that you don't have an old horribly off freq LNB. Most of the networks are specing at least 25khz stability. Some even better.

I have done so many now that once I get the hardware broken loose and close to the right EL, I typically have receivers locked in less than 30 minutes. Fine tuning and optimizing typically takes a couple hours but with the published plots in hand you should be able to find the neighborhood fairly easy.

Give me a PM or call if I can help.

Good luck,
--
Kevin C. Kidd CSRE/AMD
WD4RAT
AM Ground Systems Company
http://www.amgroundsystems.com
KK Broadcast Engineering
http://www.kkbc.com

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Deep Thought
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Re: Offical AMC 8 Transition Thread (was Sat. AMC-8)

Post by Deep Thought » Fri May 26, 2017 11:16 pm

Reading this I am so glad the last satellite receiver I put together was in 1983. :mrgreen:

Put it together, point it generally in the direction of the bird, turn on the SCPC receiver and listen for anything besides noise. 8)
Mark Mueller • Mueller Broadcast Design • La Grange, IL • http://www.muellerbroadcastdesign.com

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kkiddkkidd
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Re: Offical AMC 8 Transition Thread (was Sat. AMC-8)

Post by kkiddkkidd » Sat May 27, 2017 5:50 am

Deep Thought wrote:
Fri May 26, 2017 11:16 pm
Reading this I am so glad the last satellite receiver I put together was in 1983. :mrgreen:

Put it together, point it generally in the direction of the bird, turn on the SCPC receiver and listen for anything besides noise. 8)
Those certainly were the good old days. I carried a plain old analog TVRO and small TV to aim dishes. Up to the digital SCPC technology you could use the RX to aim. Although I did aim a number of dishes using a digital SCPC, it typically took too long to acquire to be practical.

There was TV video on practically every sat that could be used to ID the bird and then adjust for minimum sparkles. One of the radio sats didn't have video but an adjacent one did so you could find it and then move up to the desired bird.

Later,
--
Kevin C. Kidd CSRE/AMD
WD4RAT
AM Ground Systems Company
http://www.amgroundsystems.com
KK Broadcast Engineering
http://www.kkbc.com

level42
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Re: Offical AMC 8 Transition Thread (was Sat. AMC-8)

Post by level42 » Sun May 28, 2017 8:31 am

Nathaniel, I have aimed about 25 dishes now....many of them that Comtech dish. To me, those are the easiest. I use my digital protractor on the flat part of the back to set the elevation, then swing left/right until I see the plot I'm looking for on the analyzer. On some receivers, I've had to manually change the frequency to get them to lock. I can usually do a Comtech in 10 minutes, then a few more minutes for fine tuning.

I have also made some of the worst "NO way this will work" dishes work, with decent ebnos...no idea if they'll hold up over time as interference gets worse. Depending where you are located, I'd be happy to help.

Contact info here:

www.reelaudio.net

Nathaniel Steele
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Re: Offical AMC 8 Transition Thread (was Sat. AMC-8)

Post by Nathaniel Steele » Sun May 28, 2017 9:40 pm

kkiddkkidd wrote:
Fri May 26, 2017 7:44 pm


These frigging things can may you question your self worth... And then it pops on and you wonder what was so hard about that.

So I went back to that 9' dish on Friday, armed with a better spec-an. didn;t find an easy way to power the lnb at first so i tried the avcom again, for about 45 minutes. I set the skew, then the elevation, and swept around in the general vicinity hopping bird to bird to try to zero in on amc-18. xouldn't find it....so I took the feedhorn off, it looked weird to me and I should have noticed the dangling wires....it hadn't occured to me but this thing had a motor to adjust skew remotely, long since abandoned, but having a look inside (and after removing a small wasp nest which didn't seem to be affecting anything, I noticed that the rotator thingy was about 45 degrees off from what the LNB would normally be....

In the mean time, someone found me a 100' RG6 and ran it out from their distro so I could hook up the Rigol spec-an. Had it locked in in 15 minutes after that.....:) another 15-20 minutes peaking and locking down. The Rigol has three traces so I had trace one set to clear write (Normal) trace 2 to max hold, so I could see if I got off of my peak, and trace 3 to min hold, to show what the best null was when fine tuning skew. Really makes it easy....

I saw no markings on the LNB so I told them they really should have a spare anyway, and since they now don't need to order a new dish, they could probably afford the 300. XDS's had eBno about 12.5 and wegeners around 13, which I'm told was better than before the move. 1 XDS needed to be manually programmed, the other two and both wegeners had taken the programming, and the stork boxes as noted had to be manually programmed as well. I left that to bob as I had no Idea how to do so ( i tried a few things on the front panel, found the freq but couldn't figure out how to change it). I happily collected my payment and was on my way.

Now to go try that comtech again.....That guy has 2 of them and an old mesh dish that probably shouldn't work too well. I'm ready for the challenge now. I also was in a woodcraft store to pick up a router bit for a woodworking project, and saw a digital inclinometer, marketed for accurately setting your saws bevel....it has magnets. I grabbed one and will stick it to the back of that big comtech, which has no markings on it....

Thanks for the suggestions and encouragement.

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Re: Offical AMC 8 Transition Thread (was Sat. AMC-8)

Post by awsherrill » Wed May 31, 2017 10:04 pm

Last Friday, I went back for another try at the crappy mesh dish that kicked my a$$. This time I had a helper.

After thrashing around for awhile and not finding any useful signals, we finally lucked onto the right combination of azimuth and skew, and the correct waveforms magically appeared on the spec-an. Unfortunately they were only about 20 dB above the noise, and the WW1 XDS receiver would barely lock on with an EB around 5 or so. Clearly that dish will have to be replaced.

Today I wrestled with another small dish that was not likely to meet the requirements. This one was also a polar mount but it's solid metal rather than mesh. It has a crank azimuth adjustment and it was easy to move. It took a lot of cranking back and forth, but eventually we got the skew and azimuth correct and got pictures and lock. This dish works a lot better than I had hoped, and the EBs on all receivers were pretty good, ranging from 11-ish to over 15. Guess we'll see what happens with adjacent transponders lighting up.

At another site later today, we had a large Comtech dish on a rooftop with an NPRM. That one went quickly. It took longer to haul all the equipment up and down ladders and stairs than the actual repointing process. The hard part was getting the LNB skew correct...when we raised the elevation we found that we didn't have enough stepladder to reach the LNB anymore.

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Shane
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Re: Offical AMC 8 Transition Thread (was Sat. AMC-8)

Post by Shane » Wed May 31, 2017 11:24 pm

A Notice of Proposed Rulemaking up on the roof? Oh, wait......Non Penetrating Roof Mount! Had me scared for a second or two after 50 years of dealing with the other kind of NPRM.

If you fat-finger NPRM you get NORM. Remember Norm Roberts? He just retired beginning of this year.

Squirrel!
Mike Shane, CBRE
---Omaha---

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Re: Offical AMC 8 Transition Thread (was Sat. AMC-8)

Post by wtcmeng » Thu Jun 01, 2017 1:04 pm

So I am running out of ideas on how to resolve the interference issues to the Orbital and WW1 downlinks. Over the last week I was able to track down the operators of three out of the four possible interference sources. Each agreed to power off there equipment.

I did not see the noise floor change or carrier level come up. If the last possible interference source powers off and this does not clear up my issue. I may be looking at moving the dish offsite to another location and relaying audio and control closures back to the studio. This would an expensive undertaking and a road I really don't want to go down.

Any suggestions???

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kkiddkkidd
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Re: Offical AMC 8 Transition Thread (was Sat. AMC-8)

Post by kkiddkkidd » Thu Jun 01, 2017 5:18 pm

wtcmeng wrote:
Thu Jun 01, 2017 1:04 pm
So I am running out of ideas on how to resolve the interference issues to the Orbital and WW1 downlinks. Over the last week I was able to track down the operators of three out of the four possible interference sources. Each agreed to power off there equipment.

I did not see the noise floor change or carrier level come up. If the last possible interference source powers off and this does not clear up my issue. I may be looking at moving the dish offsite to another location and relaying audio and control closures back to the studio. This would an expensive undertaking and a road I really don't want to go down.

Any suggestions???
Take your LNB and specan to their roof top and poke around. Go to the other side of their building and 90degrees and see if the interference still comes from that rooftop. It could be beyond that building. That interference is coming from somewhere...

Somewhere, I have a wave guide "horn" that will increase the gain and directionality of a bare LNB. I haven't seen it in years but since I never throw anything away, I know it is still around somewhere.

I am working in Little Rock for the next week or two so can't go look now.

If your specan is a large bench unit, you might get someone with a battery powered unit to do the looking.

Regards,
--
Kevin C. Kidd CSRE/AMD
WD4RAT
AM Ground Systems Company
http://www.amgroundsystems.com
KK Broadcast Engineering
http://www.kkbc.com

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Re: Offical AMC 8 Transition Thread (was Sat. AMC-8)

Post by TPT » Fri Jun 02, 2017 6:04 am

We have a 1984 vintage Comtech, so decided to buy a new dish. Got a 12' DH dish in March, been sitting in the garage while we got around to building the pole.

Wednesday four of us tried to haul the mounting ring (not the dish--which is made of four aluminum petals--but just the iron mounting ring). One 31 year old guy and the rest of us--61,68,70. Couldn't get it on top of the pole. Re-rigged Thursday with a gin pole, got some muscle, hauled it up and on top of the pole. Now we'll try to assemble the "petals."

We're going to start reading books over the air....

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Re: Offical AMC 8 Transition Thread (was Sat. AMC-8)

Post by KPJL FM » Fri Jun 02, 2017 7:27 am

Replace the 31 yo with an older guy...
Trim to fit, paint to match, tune for minimum smoke.

ncradioeng
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Re: Offical AMC 8 Transition Thread (was Sat. AMC-8)

Post by ncradioeng » Fri Jun 02, 2017 9:15 am

Here's some pictures of the 12' DH antenna - I've put two together and have one to go.

download/file.php?mode=view&id=1370
download/file.php?mode=view&id=1369
Attachments
IMG_0239.JPG
IMG_0243.JPG

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