UNPACKING & ASSEMBLING THE DISH

STEP 6 -- UNPACKING & ASSEMBLING THE DISH

IMPORTANT NOTE: Parabolic antenna dishes may vary from one manufacturer to another. The guidelines which follow apply to most types of dishes. Please adapt and apply these principles to the dish you are using. Follow the manufacturer’s instructions closely, making at least 1 photocopy for your records. If you do not have a copy of the manufacturer’s instructions, ask ATN for a more detailed version of this Step, which includes photos.

If you are not going to install the dish immediately, carry out this step anyhow, to ensure that you have all the parts of the dish. Especially if parcels have been damaged, missing parts need to be traced as soon as possible.

6.1 Unpack the parts.
Find a flat, clean surface to unpack the parts. Carefully unpack the parts, grouping similar ones together. Take care not to bend or damage any parts during unpacking. Keep shipping papers and documents for 3 months. Keep the instructions permanently in a plastic bag or suitable folder.

Picture 7
Two sections of adjacent mesh6.2 Check to ensure that all parts have arrived
Use the list of parts supplied by the manufacturer.
Start at the top of the list and check (tick/mark) against each line.
If some parts have not arrived, immediately contact whoever delivered the parcels to locate missing parts.

Take the packet of nuts & bolts and sort into piles of the same type.
Put each type into separate packets or plastic bags.
If you will not assemble the dish the same day, keep especially the smaller parts, such as the Feedhorn /LNB in a secure place.


6.3 Assemble the dish
Read the manufacturer’s instructions at least twice, noting whether you will need any special tools or assistance.

If you want to have good reception and clear pictures, the dish antenna must be carefully assembled to ensure a precise parabolic shape. Any distortion or twisting of the shape will reduce the effectiveness of your reception. Take care not to bend or damage any parts during assembly.

Important: During assembly tighten the bolts and nuts loosely with fingers only to save time in the final stages.

Assemble the dish antenna, in the following order:


Stage 1 ASSEMBLE THE FRAMEWORK


Stage 2 ATTACH THE MESH
Note: Be sure the mesh is consistent all the way around the dish - there may be a reflective coating or a distinctive weave / pattern

Important: The mesh is attached to the frame with plastic buttons (or hooks / screws), some of which can be used ONCE only . To remove a button, it would need to be cut off, and could not be used again.

Great care needs to be taken to insert a button only when the mesh is in the correct position. In cases where the buttons pop out, they may be replaced at regular intervals with self-tapping screws (with small heads) or possible small bolts.

TIP: In high wind areas, place beads or strips of silicone glue on the ribs before attaching the mesh.

Check that each section or the rim or edge is the same distance from the flat surface, then tighten all the bolts and nuts. (Important: DO NOT OVERTIGHTEN BOLTS, as this could cause the dish to be distorted or the threads of the nuts or bolts to be damaged.

Check the shape
After assembly, turn the dish to face upwards and carefully “sight” all the way around, along the rim, (with your eye at the level of both the near and far rim) to check that the rim is straight. If not, the dish is warped and needs correction by loosening the bolts and re-setting.

TIP: Tape two pieces of string from one rim to the opposite rim at right angles to each other. These strings should touch very lightly. If the strings are separated where they meet, or too tightly together, the dish rim is not in line and the shape is not correct.

Stage 3 ATTACH THE POLE MOUNT

Stage 4 ASSEMBLE AND MOUNT THE LNB TRIPOD

TIP: In hail areas, protect the face of the dish with shade cloth (30 - 40% screen).


Stage 5 MOUNT THE LNB ON THE TRIPOD

1) The feedhorn / LNB must be centred on the dish. This may be done by carefully measuring from the rim to the throat of the feedhorn from 4 different sides and adjusting the feedhorn until all measurements are identical.

Another way would be use two pieces of string as in Section 6.3. Ensure that they touch lightly exactly in the centre of the dish. The point at which they cross should be the centre, which should be visible in the centre when looking at them through the feedhorn.

2) Mount the LNB in the Scalar Ring. See Picture 20.
Picture 20
Positioning Feedhorn
in Scalar Ring



6.4 LNB Setting
At this stage, there are two critical settings on the LNB. It is easier make these settings now, but they could be done after the dish has been mounted on the pole, together with the settings described in Section 7.4
These settings are:
1) f/ D ratio (precise distance or focal length from centre of dish),
2) Offset of the LNB (degree of rotation),

Setting No 1 (The focal length)
The focal length is the distance from the deepest point in the center of the dish to the front of the feedhorn on the LNB. On the Acer LNB this is 30mm inside. Others may vary. To start with, look for the markings on the side of the LNB and set the focal length in the middle of these markings. You can fine tune later.

For technical specialists: Refer to the instructions for your dish to obtain the correct focal length. If you do not have the instructions, you may need to use the formula below, where D = diameter of dish, d=depth of dish (measured in the center from the face to deepest point). Use a piece of string drawn tightly across the center of the face from one rim to the opposite rim to get an accurate face position. The focal length is = f

The formula is: f = D x D / 16 x d.
Example: D = 2.3m and d = 0.375m. f = 2.3 x 2.3 / 16 x 0.375 = 5.29/6 = 0.882m

Setting No 2 (The degree of rotation or polarization offset)
NB: On polar mount dishes, the 0 - 180° line should be parallel to the polar axis.

On fixed dishes, the polarization offset needs to be set on the LNB, which
is usually marked on the top with settings of 10, 20 30 and more degrees. See Picture 21. This should be measured assuming 0 degrees is at the 12 O’clock position (pointing straight up).

Hemisphere
Offset degrees
Rotate LNB*
Southern
Positive
Anti-clockwise
Northern
Negative
Clockwise

* When viewed from rear of LNB (as per Picture 21)

Example: For Johannesburg 53° offset requires the LNB to be rotated

anti-clockwise (to the left) by 53°
Picture 21
Side/rear view of Acer LNB
showing offset degrees
on the rear.
STEP 6 -- UNPACKING & ASSEMBLING THE DISH

IMPORTANT NOTE: Parabolic antenna dishes may vary from one manufacturer to another. The guidelines which follow apply to most types of dishes. Please adapt and apply these principles to the dish you are using. Follow the manufacturer’s instructions closely, making at least 1 photocopy for your records. If you do not have a copy of the manufacturer’s instructions, ask ATN for a more detailed version of this Step, which includes photos.

If you are not going to install the dish immediately, carry out this step anyhow, to ensure that you have all the parts of the dish. Especially if parcels have been damaged, missing parts need to be traced as soon as possible.

6.1 Unpack the parts.
Find a flat, clean surface to unpack the parts. Carefully unpack the parts, grouping similar ones together. Take care not to bend or damage any parts during unpacking. Keep shipping papers and documents for 3 months. Keep the instructions permanently in a plastic bag or suitable folder.

UNPACKING & ASSEMBLING THE DISH
Picture 7
Two sections of adjacent mesh6.2 Check to ensure that all parts have arrived
Use the list of parts supplied by the manufacturer.
Start at the top of the list and check (tick/mark) against each line.
If some parts have not arrived, immediately contact whoever delivered the parcels to locate missing parts.

Take the packet of nuts & bolts and sort into piles of the same type.
Put each type into separate packets or plastic bags.
If you will not assemble the dish the same day, keep especially the smaller parts, such as the Feedhorn /LNB in a secure place.


6.3 Assemble the dish
Read the manufacturer’s instructions at least twice, noting whether you will need any special tools or assistance.

If you want to have good reception and clear pictures, the dish antenna must be carefully assembled to ensure a precise parabolic shape. Any distortion or twisting of the shape will reduce the effectiveness of your reception. Take care not to bend or damage any parts during assembly.

Important: During assembly tighten the bolts and nuts loosely with fingers only to save time in the final stages.

Assemble the dish antenna, in the following order:


Stage 1 ASSEMBLE THE FRAMEWORK


Stage 2 ATTACH THE MESH
Note: Be sure the mesh is consistent all the way around the dish - there may be a reflective coating or a distinctive weave / pattern

Important: The mesh is attached to the frame with plastic buttons (or hooks / screws), some of which can be used ONCE only . To remove a button, it would need to be cut off, and could not be used again.

Great care needs to be taken to insert a button only when the mesh is in the correct position. In cases where the buttons pop out, they may be replaced at regular intervals with self-tapping screws (with small heads) or possible small bolts.

TIP: In high wind areas, place beads or strips of silicone glue on the ribs before attaching the mesh.

Check that each section or the rim or edge is the same distance from the flat surface, then tighten all the bolts and nuts. (Important: DO NOT OVERTIGHTEN BOLTS, as this could cause the dish to be distorted or the threads of the nuts or bolts to be damaged.

Check the shape
After assembly, turn the dish to face upwards and carefully “sight” all the way around, along the rim, (with your eye at the level of both the near and far rim) to check that the rim is straight. If not, the dish is warped and needs correction by loosening the bolts and re-setting.

TIP: Tape two pieces of string from one rim to the opposite rim at right angles to each other. These strings should touch very lightly. If the strings are separated where they meet, or too tightly together, the dish rim is not in line and the shape is not correct.

Stage 3 ATTACH THE POLE MOUNT

Stage 4 ASSEMBLE AND MOUNT THE LNB TRIPOD

TIP: In hail areas, protect the face of the dish with shade cloth (30 - 40% screen).


Stage 5 MOUNT THE LNB ON THE TRIPOD

1) The feedhorn / LNB must be centred on the dish. This may be done by carefully measuring from the rim to the throat of the feedhorn from 4 different sides and adjusting the feedhorn until all measurements are identical.

Another way would be use two pieces of string as in Section 6.3. Ensure that they touch lightly exactly in the centre of the dish. The point at which they cross should be the centre, which should be visible in the centre when looking at them through the feedhorn.

2) Mount the LNB in the Scalar Ring. See Picture 20.
Picture 20
Positioning Feedhorn
in Scalar Ring



6.4 LNB Setting
At this stage, there are two critical settings on the LNB. It is easier make these settings now, but they could be done after the dish has been mounted on the pole, together with the settings described in Section 7.4
These settings are:
1) f/ D ratio (precise distance or focal length from centre of dish),
2) Offset of the LNB (degree of rotation),

Setting No 1 (The focal length)
The focal length is the distance from the deepest point in the center of the dish to the front of the feedhorn on the LNB. On the Acer LNB this is 30mm inside. Others may vary. To start with, look for the markings on the side of the LNB and set the focal length in the middle of these markings. You can fine tune later.

For technical specialists: Refer to the instructions for your dish to obtain the correct focal length. If you do not have the instructions, you may need to use the formula below, where D = diameter of dish, d=depth of dish (measured in the center from the face to deepest point). Use a piece of string drawn tightly across the center of the face from one rim to the opposite rim to get an accurate face position. The focal length is = f

The formula is: f = D x D / 16 x d.
Example: D = 2.3m and d = 0.375m. f = 2.3 x 2.3 / 16 x 0.375 = 5.29/6 = 0.882m

Setting No 2 (The degree of rotation or polarization offset)
NB: On polar mount dishes, the 0 - 180° line should be parallel to the polar axis.

On fixed dishes, the polarization offset needs to be set on the LNB, which
is usually marked on the top with settings of 10, 20 30 and more degrees. See Picture 21. This should be measured assuming 0 degrees is at the 12 O’clock position (pointing straight up).

Hemisphere
Offset degrees
Rotate LNB*
Southern
Positive
Anti-clockwise
Northern
Negative
Clockwise

* When viewed from rear of LNB (as per Picture 21)

Example: For Johannesburg 53° offset requires the LNB to be rotated

anti-clockwise (to the left) by 53°
Picture 21
Side/rear view of Acer LNB
showing offset degrees
on the rear.