CODAN 5700/5900-SERIES TRANSCEIVERS

INSTALLATION & OPERATION GUIDE

About this guide.....

This is an installation and operation guide for the 5700 and 5900 series transceiver, intended for use by installation technicians who are dealing with the most common equipment line-up, i.e.:

- 5582 Power Supply Unit,

- 5700 C-Band Converter Module,

- 5712H (120W), 5760 (60W), 5730 (30W), 5720 (20W), 5710 (10W), or 5705 (5W) C-Band SSPA,

- LNA, CalAmp, ITT or Maxtech, with or without TRF.

- 5900 Ku-Band Converter Module

- 5940 (40W), 5916 (16W), 5908 (8W), 5904 (4W), or 5902 (2W) Ku-Band SSPA

- LNB, NJRC or Norsat, with or without TRF.

A short section also highlights some of the most important issues with Redundancy installations.

It does NOT cover indoor interface units, or RS-232 control. For complete information, it is essential that you consult the relevant user manual.

If you read nothing else, please read

section 1.1 about moisture......

Contents

1. Important Installation Notes

1.1 Moisture

1.2 Position

1.3 Earthing

1.4 Lightning protection

1.5 Welding

1.6 Redundancy

1.7 Mains Supply Module notes


1. Important Installation Notes

1.1 Moisture

For long-term reliability of satellite communications equipment, there are few factors more important than protecting all components of the installation from moisture ingress.

Even with well-sealed equipment modules, moisture is still the main enemy of any satellite ground station !

The Codan modules are well sealed - better than any other commercial

C or Ku-band equipment available - but it is still essential to provide as much environmental protection as possible. For example, wherever practical, mount modules under cover of the dish. However, also take into consideration any likely areas where water run-off will be channeled into concentrated streams. (Some dishes have a central hole in the reflector, and when heavy rain falls, water gushes through it !)

The Codan modules have removable panels, which should only be taken off the equipment when absolutely necessary, to minimise the opportunity for moisture (even just humid air) to enter the modules. Take great care not to allow rain to enter the Converter Module when the transparent front panel or the other access covers are off.

Key areas at which satellite stations fail are at cable and waveguide connection points. Avoid this by following the practices below:

- Ensure all waveguide joints are correctly gasketed. Make sure that if you are joining two waveguide flanges that are both grooved (CPRG type), you use a full-thickness gasket. Only use half-thickness gaskets if one surface is flat.

- Ensure all N-type connections are fully taped.

There are three main areas where N-connectors leak, and the sIightest amount of water in a microwave coaxial connection will almost completely attenuate the signal.

The first area is around the connector junction, i.e, where the plug is screwed onto the socket. This junction must be well taped with self-amalgamating tape, also known in the industry as “rubber tape”. The tape must cover the joint so that no water can work into the thread between the plug and socket. It must also cover the plug itself, between the turning and fixed parts of the plug, to prevent water entering the second critical area.

The third area susceptible to water ingress is where the cable (or heliax) enters the back of the plug. It is NOT sufficient to rely on heatshrink tubing over the connector body to seal this point, because even the best heatshrink glues do not adhere reliably to the cable outer sheath or to the shiny metal connector body. Once again, it is essential to tape this area to prevent water getting into the back of the N-plug.

In summary, the N-connections should be carefully taped from the plug/socket junction right to the cable itself.

- All other connectors must also be taped. Although many control and power connections are made with ‘MS’ (Military Style) connectors, it is still recommended that these junctions are fully taped, like the N-connections outlined above. That is, tape from the fixed equipment socket (or plug) body, right over the cable connector, to the cable sheath. This may take some time to do, and use a lot of tape, but is worth the trouble.

-  Some cable N-type connections have 1-2 inches of tubing/sheath – ensure the tape goes beyond the end of this sheath. Moisture creeps in beneath the sheath!

One final caution about self-amalgamating (‘rubber’) tape:

A: if it is stretched too much on application, it tends to break away after a few weeks or months. Take care, especially over the protruding parts of ‘MS’ connectors, not to stretch the tape too tightly.

B: if it is not stretched enough it will allow moisture to creep in from the ends.

Read and follow the instructions on the tape wrapper:

REMOVE SEPARATOR

STRETCH THE TAPE TO AT LEAST 2/3rd OF ITS ORIGINAL WIDTH.

APPLY HALF-LAPPED

Common available 19mm wide self-amalgamating tapes are 3M Type 23 Scotch and the Scapa Tapes Rotunda 2501 PIB self amalgamating tape.


1.2 Position

Detailed comments about the installation of the transceiver modules are in the user manual, however a summary of important points is given below:

5700 / 5900 Converter Module

Although a protected position is always preferable for outdoor electronic equipment, the Converter Module is designed to withstand exposure to outdoor weather conditions.

For offset-fed antenna installations, the Converter Module is often mounted on the feed support boom. Another place often chosen is the rear (underside) of the dish, using any convenient metal struts. Remember, though, that the normal interconnecting cable length to the SSPA is only 2m, and the SSPA itself should be as close as possible to the feed point.

It is also important that the Converter Module front controls and indicators, and the two metal access covers that conceal the fuse and option switches, be readily accessible.

SSPA

To avoid wasting SSPA output capacity, the SSPA should be mounted as close as practical to the antenna feed point.

Ensure that the fan shroud (if fitted) is in the lowermost position and that the open end of the shroud is facing downwards to minimise rain entry. You can reverse the shroud position by loosening the six M5 socket cap screws, enabling the shroud to be removed and re-installed the other way round.

LNA / LNB / TRF

To maintain a good station G/T (noise performance figure), the LNA (or LNA with Transmit Reject Filter attached) should always be directly mounted on the antenna feed. Don’t forget the appropriate waveguide gaskets (see section 1.1).

Note: Don’t forget to select the correct Converter Module option switch position depending on the type of LNA or LNB you have. If it is a CalAmp LNA, it needs the DC feed from the Converter Module RF input connector (i.e, back up the heliax), and the LNA+15V option switch ON. If it is a Maxtech LNA, it may have a separate power and alarm cable, and the switch should be OFF.

All LNB’s supplied by Codan require the LNB+15V option switch to be on so as to supply the +15VDC and 10 MHz reference to the LNB.


1.3 Earthing

It is important to understand the different earth potentials that may exist in a communications system, both from a safety perspective and to help with maintenance and fault finding. It is also recommended that external earth straps are used to bond equipment together (including antenna hardware) in order to minimise the likelihood of mains or RF interference with the communications signals themselves. This is discussed in more detail in section 1.4.

A brief description is given below of the different earths in the Codan transceiver:

Figure 1 (below) shows a simplified schematic of the 5581 Power Supply Unit. The AC mains is applied to the primary of the toroidal transformer, and should be accompanied by a good mains ground connection. The mains ground is bonded to the 5583 chassis, and also to the transformer’s electrostatic shield. On the DC side, note that the positive rail of the 48V supply is grounded.

The 48V then goes to the 5700 or 5900 Converter Module, and then on to the SSPA. The DC input circuits of these modules are completely floating, but the internal low voltage rails for the RF circuits are referenced to the RF ground (chassis).


1.4 Lightning Protection

At installations where there is a potential for lightning discharges, precautions must be taken to prevent dangerous voltage potentials between the outdoor equipment and the indoor equipment. At the very least, it is recommended that the metal structures of the outdoor equipment are well grounded with earth stakes, or in the case of roof-top sites, to the building lightning grid and earth system.

One of the key causes for equipment failure is not direct lightning strikes, but the large voltage potentials set up between separate earth points when a strike in the area (perhaps even several hundred metres away) causes huge ground currents. For this reason, some lightning engineers recommend the use of large copper earth straps (or braid) to connect the indoor and outdoor equipment earth systems, thus minimising the potential differences that can be set up between the two.

For critical installations in lightning-prone areas, it is strongly advised that you seek expert advice on lightning protection.

1.5 Welding

In section 1.4, it was pointed out that damage to equipment from lightning strikes is often due to the large potential differences set up when heavy currents flow through resistive grounds. A similar effect can occur due to large welding currents, when electric arc welding takes place on the antenna structure or associated metalwork.

If someone is about to weld on or near the antenna structure, take the following precautions to minimise the danger of large welding currents flowing through the communications cables:

- Disconnect all cables from the indoor equipment, including power, control and IF cables.

- Disconnect all cables between the Mains Supply Module, Converter Module, SSPA, and LNA.


1.6 Redundancy

Step-by-step installation instructions are given in the “C-band Transceiver Redundancy Switching Equipment User Manual” . However, the important installation notes of this document also apply to redundant transceiver sites. Because these are often network hub sites, or critical headquarters installations, it is even more important to ensure the utmost equipment reliability. Although the transceivers themselves are duplicated, there is, of course, the switching equipment which is not duplicated. Therefore:

- Especially ensure that the waveguide / coaxial switch(es) are protected from damage during handling and installation. Do not bang or dent the manual override cover, and ensure no dirt or water enters the waveguide openings.

- Don’t forget to use appropriate half or full waveguide gaskets, as required, when joining the LNA’s, LNB’s and TRF or feed to the waveguide switch.

- It is essential that all the transmit heliax connections to the coaxial switch section are fully protected against moisture ingress, as detailed in

section 1.1. It may, in fact, be quite difficult to get the “rubber tape” successfully around each plug on the coaxial switch, due to the confined space. However, it is no less important to seal each connection, and in the event that you can not get tape around all four connectors, use another method to complete the seal - e.g, wrap the rear of the connectors with tape, and force silicon sealing compound into the plug/socket area until you are satisfied that no water can get in.

- If you have to remove the manual override cover for any reason, be extremely careful when replacing it, as there is very little clearance between the cover and the mechanism. If not aligned correctly, the cover will scrape the side of the mechanism, and prevent it from moving when electrically switched. It is therefore necessary to test the switch operation after replacing the cover, to make sure it still operates freely. Also make sure it is re-assembled with the ‘O’-ring seal.

For complete operating instructions for a redundant system, see the “Redundancy Switching Equipment User Manual”. Some useful tips are noted below:

- Ensure that some regular program of testing switch-overs is instigated. It is important for high system reliability that the ‘off-line’ equipment is always available and operational - it is no good having a failure in the on-line transceiver, then suddenly discovering that the redundancy system fails to switch-over, or there is a fault in the ‘off-line’ transceiver.

- Many system providers prefer to have the off-line SSPA permanently activated. That is, both Converter Modules have their SSPA switch in the ACTIVATE position. This has the advantage that the off-line SSPA status is also being monitored, and any faults that may occur (including fan faults) will immediately be indicated. Codan recommends this mode of operation unless there is a specific requirement to save primary power. There will be no reduction in the life-time of the SSPA’s by having them both permanently activated.

1.7 Power Supply Unit notes

The 5582 Power Supply Unit is a robust, wide-range power supply specifically designed for the Codan C-band transceiver.

- The 5582 is an unregulated power supply and operates like a simple transformer/rectifier supply. The DC voltage fed to the transceiver will be somewhere between 37V (at very low mains) and 60V (at about 115/230V). This high voltage will not cause damage to the Up / Down Converters or SSPA modules as the DC to DC converters inside the UDC and SSPA are designed to accept an input voltage of 72V DC.