realigning the arc

Galway

I have lost some satellites on my motorised system,only really getting 19.2 and 13 east properly. 28 east, 5 west weaker than before and 30W hispasat is gone.

16 miles north of Galway city, so true south is 8 west, yes? So would i needed to peak the signal on 8 west and then providing motor setting is at zero,it should trac arc and then I make any tweaking adjustments? Its is jaeger 36 volt motor not a diseqc.

Any help/advice greatly appreciated.

Zaphod

Is it a H-H mount or a polar mount?

9W would be closer for Galway, but 8W is near enough. For small dishes it's usually OK to align the mount by peaking the dish using a sat near true south. For larger dishes the technique outlined here is more accurate:
http://www.geo-orbit.org/sizepgs/tuningp4.html

Galway

Zaphod wrote:

Is it a H-H mount or a polar mount?

9W would be closer for Galway, but 8W is near enough. For small dishes it's usually OK to align the mount by peaking the dish using a sat near true south. For larger dishes the technique outlined here is more accurate:
http://www.geo-orbit.org/sizepgs/tuningp4.html

Its H to H Jaeger 128 but now I have another proble

MY motor has started sticking when moving west,east is ok but it sticks and refuses to move west ,and I get the message "actuator error,check the line" in my technomate receiver. Are the motor gears damaged? Can anything be done?

Zaphod

Swap the M1 and M2 cables at the receiver, click 'east' and see if the mount moves west. If it does but still doesn't go in the opposite direction, then problem is with receiver. Try a factory reset.

If motor still doesn't move west then problem is with mount. Usually this is due to a faulty reed switch but that would normally cause problems going east and west. But it might still be worth replacing. Take back of motor housing and check limit switches. Check the gears too.

If you've got an old car battery, move the motor with that and check that the reed switch is opening and closing with a multimeter.

Galway

motor seems to have righted itself now but rapid drop off form 13 east,nothin futher east comin thro - I had astra 19.2 east and 28. 2 east b4. Full 100% quality on 5 west down a bit on Hispasat.Sounds as if it going above arc? Maabe pole isnt plumb either.any thoughts?

I am right in thinkin that with a motorised system youa re always gonna loose a bit on some sats as theres no skew control as against a fixed dish?


For example could bearly ever get Hellasat 39 east or Turksat 42 east b4 while arc from 28.2east to 45 west as pretty spot on.

Zaphod

Galway wrote:

motor seems to have righted itself now but rapid drop off form 13 east,nothin futher east comin thro - I had astra 19.2 east and 28. 2 east b4. Full 100% quality on 5 west down a bit on Hispasat.Sounds as if it going above arc?

Presumably the elevation and declination angles haven't been changed, so all that's wrong is the north/south alignment.

Did you read Section 6 in the above link where he discusses moving the mount to an easterly or westerly sat and lifting/lowering the dish to see if it changes the signal level??

Galway wrote:

Maabe pole isnt plumb either.any thoughts?

Get a level and check.

Galway wrote:

I am right in thinkin that with a motorised system youa re always gonna loose a bit on some sats as theres no skew control as against a fixed dish?

No, it's the opposite. With a fixed offset dish, the long axis is always vertical even when the LNBF is skewed. So at extreme east/west, the skewed LNBF will be illuminating only part of the dish and also picking up ground radiation.

With a H-H mount, the entire setup is tilted as you moved east/west, so that both the dish and LNBF are skewed. Therefore the dish is always properly illuminated by the LNBF.



solid line - dish; dashed - LNBF illumination; red & blue - LNB H/V probes

watty

I think Zaphod he is referring to fact that a few satelllites are not exactly on same axis. C Band and some professional gear allows per satellite skew adjustment with a separate polariser on a flange mount LNB and separate horn.

On a motorised system don't fine tweek the skew on 28E! But on Thor 1W or something a bit weaker.

Zaphods explaination of dish illumination is correct and shows the advantage of a manual polar mount on a fixed dish. I had a homemade fixed polar mount for a few years and it ment too that if I wanted a different fixed satellite I did not have to adjust Elevation (or generally LNB skew).

Zaphod

watty wrote:

I think Zaphod he is referring to fact that a few satelllites are not exactly on same axis.

I thought that too initially but he asked about it in the context of:

Galway wrote:

For example could bearly ever get Hellasat 39 east or Turksat 42 east b4 while arc from 28.2east to 45 west as pretty spot on.

To be honest, a frying pan could bring in the european beams on 42E so this points to a problem with the mount alignment and not skew. Or else you don't have a clear LOS. 95%+ of the time, the skew provided by the mount as it tilts the dish is perfectly sufficient and is better than a fixed dish.

It's only in the very odd cases where the polarisation doesn't follow the line of the arc.


Then polariser control is required to get the best signal. So, in general, for an offset dish:

HH mount with polarotor > HH mount with fixed H/V > Fixed dish with fixed H/V

(it isn't quite the same for prime focus dishes)

But if you're finding it difficult to align the mount with a standard LNBF, you'll find it considerably more difficult to do so with a polarotor feedhorn.

Galway

Can get 42 and 39 East blasting in if dish fixed on them so its not LOS prob. Arc from 42 east to 45 west is receivable at my location, so have to get the guy to look at the mount settting I think.All this advice is useful. Providing motor is properly set up and is tracking arc, the way the motor angles the dish particularly on those satellites past 28 east where elevation is lower mean the skew does not matter as the dish itself is being skewed by the motor as it tracks the arc. I think this is waht you mean?

This is all very useful info. I will pass it on the installer,who has promised he will be here tom eve!

watty

Yes.

Skew is only an issue for a few wierd sats. Sky (Which AStra?) is alleged to be not quite on same axis, but close enough with massive signal. With a 110cm dish I get 100% quality on some transponders on 30W, 5W, 28E and 42E

watty

Which sat in the west Zaphod does your excellent diagram suggest has a wierd polarisation?

Of course with Circular polarisation the angle of the satellite or LNB doesn't matter .... Popular long ago when some sats had a slight spin to stabilise them.

Zaphod

Galway wrote:

Providing motor is properly set up and is tracking arc, the way the motor angles the dish particularly on those satellites past 28 east where elevation is lower mean the skew does not matter as the dish itself is being skewed by the motor as it tracks the arc. I think this is waht you mean?

Spot on!

Just align the LNBF with the major axis of the dish and leave it at that. Let the mount take care of the rest.

Assuming you have LOS you should be able to go as far as 58W as this has a good signal over Ireland. Then you have:

58W - 50 deg - 8W - 50 deg - 42E

45E should also be possible.

Also as Watty mentioned, when it's all set up, see if you can bring in any channels on Thor/Intelsat 10-02 @ 1W . This is fairly weak and a good benchmark to test if you're on the arc - not all channels are receivable however.

What size dish have you?

watty wrote:

Which sat in the west Zaphod does your excellent diagram suggest has a wierd polarisation?

Watty, my not-quite-so-excellent diagram is for educational purposes only! In fact, the sat with the strangest polarisation in our region is the one most people use as the reference for true south i.e. 8West.

This is a neat example of a DIY external mechanical polariser used on 8W.

Sig quality without polariser:


Sig quality with polariser:


Polariser in action:



The unit in the pic is based on the one sold by Reisat in Switzerland which sells for approx. €1200. And that's before you buy the LNB or feedhorn!

watty

Looking at 58W I only see:

PAS 9 © Lyngemark Satellite, last updated 2006-07-22 - http://www.lyngsat.com/pas9.html
Freq.
Tp 	
	Provider Name
Channel Name 	
	Video
Encryption 	SR-FEC
SID-VPID 	NID-TID
Audio 	Beam 	Source
Updated
11477 H
tp 1 	Satlogo 	British Telecom 	AddressUplinkStation 	DVB 	26463-3/4 	1-0
	Conus & Europe 	F Kocsis
060524


	DD India 	Address 	PowerVu 	    1	1160 	1120 Hi
Aastha International 	Address 	Free TV 	    2	1260 	1220 Hi
(British Telecom feeds) 	
	
	    3	1360 	1320
(British Telecom feeds) 	
	
	    4	1460 	1420
(British Telecom feeds) 	
	
	    5	1560 	1520
11509 H
tp 3 	

	(feeds) 	
	DVB 	6620-3/4 	
	Conus & Europe 	F Kocsis
060312
11522 H
tp 3 	

	(feeds) 	
	DVB 	6022-2/3 	
	Conus & Europe 	Jonali
060713
11530 H
tp 3 	

	(TVBS feeds) 	
	DVB 	6620-3/4 	
	Conus & Europe 	L Swaan
041111
11542 H
tp 5 	

	(feeds) 	
	DVB 	6666-7/8 	
	Conus & Europe 	Anonymous
060709
11557 H
tp 5 	

	(feeds) 	
	DVB 	6620-2/3 	
	Conus & Europe 	F Kocsis
060321
11582 H
tp 7 	

	(feeds) 	
	DVB 	5632-3/4 	
	Conus & Europe 	L Swaan
040511
11600 H
tp 7 	

	(feeds) 	
	DVB 	6620-3/4 	
	Conus & Europe 	James A
050226
11612 H
tp 7 	Satlogo 	Cubavisión Internacional 	AddressNet TV 	DVB 	3670-3/4
    1 - 1160 	1-1
1120 Sp 	Conus & Europe 	W Walter
030307

TThat might be got here?

Galway

Not much at all on 58 west i got it once before on my setup.Happy enough if i can get from 42east to 43 west.So heres hopin it sorted this evenin, as its a realignment not total reinstall i m hoping it wont take forever. But will get guy to check pole is plumb,mount is et correct for 53 deg latitude and, dish is intially peak on 5 west or 8 west, then try to get satellites at the east and west extremities without impairin 5 west of course.

Zaphod

@Watty, Not much to see on 58W apart from Cubavision (fta) and DD India (encrypted) but enough to align the dish. Most of the stuff is in C-band.


I've attached a scan of the standard alignment procedure below. As it's from an old American book, I've deleted some bits which aren't relevant. References to 'faintest picture' etc are meant for an analog system - you'll have to use the receiver's quality meter or a signal meter for a digital system. All the checking/finetuning described might be overkill for a small dish, but it will guarantee that the mount is aligned.

Galway

the guy coming has a spectrum analyser so that should help yes?

MenloPete

If it's really true that a frying pan would receive 42E, how come I can get absolutely nothing there on my Lidl 60cm?
I receive lots of other stuff from Hispasat to Astra2.
Is 42 particularly low on the horizon? There are some trees in that direction, but no bigger than in other directions.

Peter

Galway

MenloPete wrote:

If it's really true that a frying pan would receive 42E, how come I can get absolutely nothing there on my Lidl 60cm?
I receive lots of other stuff from Hispasat to Astra2.
Is 42 particularly low on the horizon? There are some trees in that direction, but no bigger than in other directions.

Peter

yes its low..dam installer couldnt make it yday so will wait till im back from hols in 2 weeks

Galway

MenloPete wrote:

If it's really true that a frying pan would receive 42E, how come I can get absolutely nothing there on my Lidl 60cm?
I receive lots of other stuff from Hispasat to Astra2.
Is 42 particularly low on the horizon? There are some trees in that direction, but no bigger than in other directions.

Peter

yes its low..dam installer couldnt make it yday so will wait till im back from hols in 2 weeks

Zaphod

watty

A Lidl dish used for 42E would look as if it is point at ground also LNB needs twisted more. It will work.