3) Wait a 2 seconds, and the dish will move to that preset position. This info was supplied by:
Mike Ginger <B254168@aol.com>
The Following extracts are from "Satellite Secrets Revealed"
(Jack Armstrong ISBN 0-946273-07-3 Arlon House Publishing)
The "SATWALKER", fits behind the dish and moves the dish itself, rather like an H - H mount. This unit allows a satellite arc of up to 50 to be tracked. It sets skew and elevation by tilting the dish as it moves and has a manual search facility. The remote control handset makes it easy to use.
The Satwalker is available from the U.K. agents, Satellite Scene, at Derby who will be pleased to fit it for you if you live anywhere South of Leeds.
If you want to fit it yourself, Satellite Scene have kindly provided these instructions:
1. Plug the Remote Positioner box into the mains for four hours before installation to recharge its batteries, otherwise it will not remember any satellite positions.
2. Align the dish on TV Norge at 1 W initially.
3. Dish pole must be absolutely vertical and dead in line with motor unit
4. Observe polarity of motor connections to Remote Positioner as reverse polarity will cause serious damage!
5. To prevent accidental polarity reversal, you can fit a high current rectifier diode (1N5402) in series with the positive lead of the motor.
6. Use good quality 4 core cable not thin burglar alarm cable!
7. Seal connections on motor unit with bathroom sealant before bolting down the cap.
8. If possible, use an elliptical dish of at least 80cm, as light in weight as possible (we use a Hungarian aluminium dish).
9. Astra is on the west most limit of travel so make sure that the dish can move a fraction further west before setting the final position. If you don't do this, you might not be able to move the dish quite far enough to get the best possible signal from Astra before reaching the end stop.
This info was supplied by:
Mike Hancox, Technical Director, Satellite Scene, Derby.
For those of you who are keen to have a go at installing a fully motorised system, the following section is designed to help the newcomer to align the polar-mount dish properly so that it can track the geo-arc accurately.
Motorised The Easy Way
The following notes are based on personal practical experience. Once you have got the knack, the actual dish alignment takes just a few minutes and you will soon be classed as an expert!
(Definition of an EXPERT: EX = someone who used to be. SPERT = a drip under pressure.)
Preparations
Before messing around with all those bits and pieces you should familiarise yourself with the functions of the Antenna Control Unit (ACU or "Positioner") and the receiver.
Read the instruction books thoroughly
Make sure the dish has a good clear line of sight to all the satellites required.
Microwave signals can't go through trees or next door's garden shed!
Assuming you have been successful in building the dish kit, now is the time to start some real work.
The following equipment will be needed to mount and set up the dish:
loads of patience! Assuming that you already have these items, alignment will be easier if there is somebody to help you.
The best way is to take them outside; only a few connections are needed. Fix the mount in place and use your spirit level to ensure that it is truly vertical. Failure to do so will make it impossible to create the true arc needed to receive all possible satellites. A millimetre error at ground level represents tens of kilometres at 36,000 km.
Connect the coax cable from the LNB on the dish to the receiver. At this point, there is no need to connect the polariser but you will need to physically twist it in its clamp to optimise the polarity once you have located a satellite.
Connect the +36 volt wires from the actuator to the ACU (consult your User Instructions to determine the connections).
Connect the satellite receiver to the TV and tune in the test signal (consult the section on fixed dish installation).
The satellite receiver should already be pre-tuned to one channel that will work on Astra and one that will work on Intelsat V. Consult your User Instructions to determine how to select these channels.
Setting Up Dish Angles
Set the dish on its mount to its apex position so, when viewed from behind, the frame is at 90 degrees (right angles) to the pivot assembly.
Temporarily hold the dish in this position with the actuator or a similar sized bar. Slacken the bolts used to hold the polar head to the mast and turn the whole dish assembly (still in the apex position) to point approximately south. Temporarily tighten the bolts which hold it to the upright pole.
Consult an Ordinance Survey map to determine the latitude of your home. Take a look at the table on the next page to see the corresponding polar axis and apex angles.
The table gives approximate angles for setting up a dish throughout most of Europe, from Norway to Gibraltar. For use with a protractor, the angles are given to just one decimal place which is more accurate than you can use. You can find more accurate tables in other publications if you need them for a precisely manufactured inclinometer.
LATITUDE POLAR AXIS ANGLE APEX ANGLE
35 35.6 40.7
36 36.6 41.8
37 37.6 42.9
38 38.6 44.0
39 39.7 45.2
40 40.7 46.3
41 41.7 47.4
42 42.7 48.5
43 43.7 49.6
44 44.7 50.7
45 45.7 51.8
46 46.7 52.9
47 47.7 54.0
48 48.7 55.1
49 49.7 56.2
50 50.7 57.3
51 51.7 58.4
52 52.7 59.5
53 53.7 60.6
54 54.7 61.7
55 55.6 62.7
56 56.6 63.8
57 57.6 64.9
58 58.6 66.0
59 59.6 67.0
60 60.6 68.1
HOW TO MAKE AN INCLINOMETER
First take your schools protractor and a length of string, just long enough to hang below the edge of the protractor. At the centre point of the protractor attach the string so that it is able to swing freely, then tie a weight to the other end of the string. To take the measurements, hold the straight edge of the protractor against straight edges of the mount and take the reading from the curved part of your protractor.
Now you are the proud owner of an inclinometer ! POLAR AXIS ADJUSTMENT
Place your protractor upright on the rear edge of the square frame. Adjust the axis by means of the two nuts on the polar axis adjuster to the polar axis angle which corresponds to your latitude in the table. For example, if your latitude is 53 then you must set the polar axis of the dish so that the string hangs down on the 54 mark of the protractor (with 0 at the lowest corner of the protractor).
APEX ANGLE ADJUSTMENT
Place the protractor on the plate or ring which is part of the dish itself--not on the frame. If necessary, hold a piece of flat plywood across the dish face, overlapping the dish at one side, and hold the protractor against the wood. Set the apex angle by using the adjusters which connect the plate or ring to the square frame.
For example, if your latitude is 53 then you must set the apex angle of the dish so that the string hangs down next to the 61 mark of the protractor. This adjustment will automatically set the declination angle.
Be as accurate as possible!.
FINDING TRUE SOUTH
There are several ways to find true south: by using a magnetic compass and taking account of the magnetic correction or by using the sun's hour angle. Both, in my opinion, are not so easy (especially when the sun won't come out to play. ) I find the most accurate method is to use the satellites up there to help with the job. If we use Intelsat at 27.5 W then first it is necessary to determine the elevation of this bird for the receive site. For a rough guide see the accompanying map. Keep the protractor on the plate or ring which is part of the dish itself--not on the frame. Keeping the mount clamped firmly to the upright pole, swing the dish westward (to the right, looking from the back) until the angle corresponds to the angle for Intelsat 27.5W.
For example, if your location is London, the string should hang down on the 26 mark of the protractor. Clamp the dish assembly in this position with the actuator or with a temporary fixing bar.
Loosen the bolts that hold the assembly to the upright pole and turn the whole assembly slowly around on the mast until you receive a picture from Intelsat 27.5 W on the TV set (for example, the parliamentary channel). You may need to twist the LNB/polariser assembly in its clamp to optimise the polarity. Position it for the clearest picture.
Tighten the bolts which hold the dish to the upright pole. When the dish is swung back to its original centre setting it will now point to true south.
FINDING THE POLAR ELEVATION
Use the actuator or the fixing bar to move the dish eastward until a picture appears from Astra 19.2 E (e.g. Sky News). You will have to select this channel on your receiver first.
Finally, adjust the polar setting by swinging the dish slowly right and left until you have the best picture. Do not re-adjust the polariser; this will be done electrically when you connect it to the receiver!
Move the dish back to Intelsat 27.5 W and select The Parliamentary Channel and check that the picture is still good. If not, the south setting is inaccurate and you will have to start again from Finding True South.
Use the polar elevation adjustment to get the best results on Astra 19.2 E and the true south adjustment for the best picture on Intelsat 27.5 W .
Fit the actuator to the dish assembly if it is not already there.
Wiring it up properly
Once the dish assembly has been aligned and all bolts and clamps tightened, you can move the receiver indoors and fit the complete cable run.
You should use proper "Motorised Ribbon Cable". (I have been told many times that caravan cable is cheaper and works just as well if you believe that you will also believe that Sellotape makes a perfectly waterproof cable joint and that pigs can fly).
If you have difficulty in obtaining the real stuff, look at the list of suppliers in the Appendix.
Fit an 'F' connector to the end of the coaxial cable and screw it onto the LNB. There are six other wires; two thick and four thin. Strip the sections of ribbon apart and take the pair of thin wires which is by itself. These wires must be connected to the polariser. Some polarisers have rigid spade terminals: you must connect the corresponding female terminals to the pair of wires by crimping or soldering.
Some polarisers simply have two "flying" wires. Usually, a connector filled with silicone grease is supplied for each of these wires. Simply push a polariser wire and one of the cable pair into the connector and crimp it with pliers. The internal 'V' shaped blade bites into the insulation and makes contact with the copper wires.
Whatever method you use, it must be mechanically and electrically sound. Simply twisting the wires together will give endless problems after a few months! Make sure that water can not enter. It is difficult to use self-amalgamating tape on such thin wires so I would recommend that you surround the connections with my old favourite, "Blu-Tack".
Squeeze it firmly so that it encapsulates the connections to keep moisture out.
Use plastic cable ties to fasten the coaxial cable and polariser wires along the boom arm. Don't forget to leave a drip loop beneath the LNB and the polariser!
The remainder of the cable which contains two thick and two thin wires should be stripped back. Don't secure them to the boom arm but fasten them to the support bracket at the back of the dish. Leave enough slack for the dish to move without chafing or cutting the cable.
The four wires must be connected inside the actuator. Remove the cap from the motor housing. Consult the sheet which came with the actuator. You must follow the instructions on the sheet. The two thick wires will carry the current to the motor. The two thin ones will carry the pulses from the magnetically operated reed switch.
The reed switch is often encapsulated in plastic but it will always be situated next to the rotating magnet. Follow the two thin wires from this reed switch back to the terminal block. Your two thin wires in the cable should be connected to the reed switch wires by putting them into the side of the terminal block directly opposite.
Of the two thick wires in your cable, one will go to the terminal block that carries a wire straight down to the motor. Your other thick wire will go to the terminal block that has a wire connected to a microswitch, usually via a black, cylindrical diode.
The microswitches are operated by cams and effectively reverse the motor connections when the actuator approaches the end of its travel in either direction. You can re-set the limits by altering the position of each cam. Do read the instructions first.
Make sure that the wires are sealed into the cable entry grommet. It is important that water should not be able to enter. The motor housing will have a gasket to seal the lid. If this becomes damaged you must replace it. If the motor housing has a tiny vent hole, position the actuator so that the hole is underneath.
Make sure that the actuator is firmly clamped and bolted in place and that the offset angle of the moving eye does not exceed the manufacturer's maximum recommended.
The cable should be secured to the pole then routed to the building where the receiver and positioner will be situated. Use common sense when laying the cable. If you need to put it underground, pull it through a duct which will allow for future replacement when necessary.
If it is exposed, put it out of reach of drunks, children, and animals! (Rats and mice can do amazing things with satellite cable the more it costs, the more nourishment it seems to provide).
Large clips are available for nailing motorised ribbon to the wall. Be sure to state the width of the ribbon when ordering them.
Take note of the various hints and tips about cable in the Fixed Dish section of this book.
To get the cable through the wall you need a wide, flat slot drill.
Only kidding!
The way to do it is to separate the three parts of the ribbon at this point and drill three separate holes. Make sure that you leave more than enough length when you cut the cable!
Ribbon cable, even after separating, is not easy to route invisibly around the living room so try to put the cable through the outside wall as close as possible to the positioner.
Professionals often drill a 16mm hole through the wall, tape the end of the ribbon cable in a tight bundle, then push it through the single hole.
Whichever way you choose, make sure that you drill the hole(s) downward from inside the house and seal the gap around each cable with mastic sealant (or force "Blu-Tack" in).
Wiring to the positioner is easy but do read the instructions!
The most common (and expensive) mistake is to wire the two thin wires from the polariser, or the two wires from the reed switch, to the 36 volt terminals for the actuator motor. Bye bye polariser or bye bye reed switch! It is the THICK wires from the actuator motor which should be connected to the 36 volt terminals. Sometimes, these terminals are labelled M1, M2 but it varies from one receiver to another.
The two thin wires from the reed switch need to go to the relevant input terminals. Sometimes these are labelled PULSE and GND (ground) but don't rely upon it. read the manual! Don't ever connect anything to a terminal marked "5v". This terminal is for either a mechanical polarotor or a potentiometer type actuator. The latter is obsolete and the former is used only on the most expensive systems or very old ones.
The two thin wires from the polariser need to go to the polariser current output terminals, one of which is likely to be marked "GND".
If your receiver is an older type which will work only with a polarotor then you will have to buy a "ferrite interface unit" which has three wires to connect to your receiver, one of which does go to "5v" and one to "GND". The two thin wires from the polariser must be connected to the current output socket of this interface unit--usually by means of a "Phono" plug as used for audio connections. The wires will have to be soldered inside this phono plug.
Polarisers from different manufacturers require a different amount of current to change the polarity of the incoming satellite signal. Some satellite receivers allow you to select a maximum value of current via the on-screen installation menu. Most polarisers (Racal, Irte etc.) require 85mA maximum current but note that polarisers supplied by Echosphere Corporation may need only 45mA. If in doubt, start on the lowest current setting and select a higher one if you can't get enough polariser adjustment to eliminate "sparklies" or if the automatic polarity setting option (if there is one on your receiver) does not work.
Remember that you physically set the polariser for best results on Intelsat at 27.5 W when the polariser was not connected so your "skew" current value should be zero for this satellite.
Grateful thanks to David Poole of Davenham Satellites, Northwich, for providing this information about motorised systems. (Sadly, David died on June 6th, 1997).
This is an excerpt from "Satellite Secrets Revealed" (Jack Armstrong ISBN 0-946273-07-3 Arlon House Publishing) price 9.95 from SatCure.
DISCLAIMER
This information is given in good faith, based on several years of experience. No responsibility will be accepted for any death, damage or injury caused either directly or indirectly by the use of this information. The reader should check the facts himself. It is assumed and stressed that the reader will be familiar with good, safe, installation practice and will be familiar with all tools, components and terms used. If there is any doubt about the reader's ability to carry out such work competently and safely, the work should be referred to a specialist installer.
Copyright ©1997 SatCure, Mike Hancox, David Poole, Mike Ginger.
Version 1.1 updated on 3/5/99
This file may be downloaded for private and personal use but NO part of it may be published in any form without the prior permission of the author.
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