page 1 of 7 Description These feeds are designed for installation in shielded standard types of parabolic antennas. The feed is designed for positive metal-to-metal contact between the feed and the reflector, therefore no separate ground wire is required. The mounting hardware includes either standard or thin-head bolts and requires the use of 13 and 17mm wrenches. Foam absorber material on certain feeds is for RF performance. DO NOT REMOVE THIS MATERIAL. Warning: Use protective wear to avoid eye and skin contact with the compound. Keep away from mouth. Wash thoroughly after using. Do not use or store open near food or food sources. Empty or partially filled containers should be disposed of after use according to governmental regulations for petroleum products. Contents: oil, clay and zinc dust. Notes: 1. As shown in Figure 1, a foam absorber material is applied to certain feeds and is related to RF performance. Do not remove this absorber. 2. As shown in Figure 2, some feeds are furnished without vertex rings, some with vertex rings and some with vertex rings and vertex ring shims. that do not require rings are identified by a label on the front of the feed hub. 3. Do not remove the flange covers until you are ready to connect the feed to the feed lines. The flanges must remain clean and dry. 4. The feed is normally installed from the front side of the antenna. However, when a feed must be replaced on an installed antenna, consider the recommendation given in the separate section titled "Feed Replacement" Vertex Ring Figure 1. Dual-polarized Feed with Foam Absorber Notice The installation, maintenance or removal of antenna systems requires qualified, experience personnel. Andrew installation instructions have been written for such personnel. Antenna systems should be inspected once a year by qualified personnel to verify proper installation, maintenance and condition of equipment. Andrew disclaims any liability or responsibility for the results of improper or unsafe installation practices. Vertex Ring Shim Vertex Ring Feed Feed without vertex ring Feed with vertex ring Figure 2. Feed Mounting Variations Feed with vertex ring and vertex ring shim any specifications or warranties relating to products or services.
page 2 of 7 Read the following instructions thoroughly before assembly 1. on. Remove the outer plastic wrap and gloves from the mounting ring package. Use the gloves to handle the mounting ring. Certain feed mounting surfaces have corrosion inhibiting compound applied to them for contact with specific areas on the reflector. Do not remove the compound during installation. Carefully place the mounting ring against the rear surface (convex side) of the reflector, as shown in Figure 3, and place any additional plates required (see Figure 2) against the front surface (concave side). Make sure that the overlap of the mounting ring (see Figure 4) is positioned toward the top of the antenna. Also make sure that any taper of the ring or the plates matches the curvature of the reflector. rear surface M10 Bolt Nut Add conductive grease to all hardware prior to assembly. Insert four M10 hardware bolts through the assembly from the front side of the reflector. Then add a flat washer, lock washer and nut to each bolt. Finger tighten the bolts.then add the remaining bolts, flat washers, lock washers and nuts. Tighten all eight bolts evenly, torque to 38 Nm ± 5%. Polarization arrow Captivated hub-locking clamp Rear surface of reflector Flat washer Lock washer Figure 3. Installation of Overlap end of retaining ring (shown on side for illustration)must be toward top of antenna M8 hardware Torque to 18.7Nm ± 5%. Feed hub RF spring gasket M10 hardware (standard or thin head) Torque to 38Nm ± 5%. Vertex Ring (if required) Vertex Ring Shim (if required) Notes: Feed hub diameter is 8 in (205mm) Feed is always front mounted on new installations Figure 4. Feed Hub Assembly Details Vertex ring with or without vertex ring shim is front mounted Mounting ring is rear mounted Retaining ring is factory installed in mounting ring Hub locking clamps are captivated to feed hub RF spring gasket fits into groove in mounting ring any specifications or warranties relating to products or services.
Liberally apply a continuous coating of 203233-2 corrosion inhibiting compound (tube supplied) over the entire RF spring gasket. Add the RF spring gasket to the groove formed by the notch along the outer edge of the mounting ring and the surface reflector as shown in Figure 5. Compound material may be cleaned from hands with a liberal application of liquid soap and rinsed with water. Groove Tube (no spring) rear surface Spring page 3 of 7 rear surface Ball washer Ball washer Figure 5. Groove formed by mounting 2. Feed Mount ring and reflector surface Insert the feed through the front side of the reflector so that the feed hubs against the mounting ring as shown in Figure 4. Hold the feed in place and loosen the M8 hardware for the hub locking clamps. Slide the clamps into position to grip the mounting ring as shown in Figure 6 and finger tighten them to hold the feed in place. Final tightening of the clamps is done after positioning the feed for correct polarization. Clamp Correct Retaining ring Feed hub Incorrect Solid or Spring guy line Feed anchor ring Guy hook Washer Feed anchor ring Nicopress Red stripe here marks top of antenna Mounting ring Figure 6. Correct Positioning of Feed Hub Locking Clamps 3. Attach Guy Lines[If Supplied With A Feed Anchor Ring Fitted] Attach the guy lines for the feed by passing each guy line through the appropriate hole in the reflector as shown in Figure 7. The top guy line has a tube instead of a spring for some 10-foot antennas and all 12- and 15- foot antennas. Pull each guy line toward the feed and hook it to the anchor ring on the feed. Some anchor rings have a hole to accept a guy line hook. Other anchor rings have a slot that accepts the end of the guy line as shown on Figure 7. The anchor swivels to allow rotation of the feed for the correct polarization. Caution: Do not force the feed in any direction when hooking the guy lines to it as this can damage the feed. The feed must remain centered. Guy line tension is set at the factory and no further adjustment is necessary. When properly installed, all springs should be under compression and about equal in length. Spring guy lines (Front view of reflector) Figure 7. Guy Line Assembly Details Showing Alternate Attachments Note: when a 15-foot antenna is mounted in the inverted position (red stripe at the bottom position), the guy lines must be installed in three holes plugged with bolts. Reuse these bolts to plug the three unused holes in the reflector. 3. Position Feed for Correct Polarization. Rotate the feed to correct position for the polarization (horizontal or vertical) required with the feed hub clamps loosened. Refer to the examples given in Figures 8 and 9. If a guy line interferes with this rotation, temporarily unhook it. A polarization arrow is located adjacent to each feed input flange on the rear surface of the feed hub. This arrow must be parallel to the polarization required. For single polarized antennas, the arrow is positioned up or down for vertical polarization, as shown in Figure 8. Once correct feed position is obtained tighten all bolts evenly, torque to 18.7 Nm ± 5%. any specifications or warranties relating to products or services.
Vertically Polarised Feed (see polarisation arrow) Horizontally Polarised Feed (see polarisation arrow) page 4 of 7 Polarisation arrow Polarisation arrow Figure 8. Examples of Single-Polarised Feed Positions for Horizontal or Vertical Polarisation. any specifications or warranties relating to products or services.
page 5 of 7 Dual-polarized feed for HSX/UHX antennas have asymmetrical patterns with lower side lobe levels on one side. For these antennas, radiation pattern envelopes are prepared for the full 360. The frequency coordinator can use the better half of the radiation pattern on either the right or the left side of the antenna to reduce potential interference. The UHX/HSX feed hub is identified by red tape fitted to the waveguide to identify the better side. The red tape side can be placed either to the right or the left of boresight. Therefore, it is necessary for the frequency coordinator to specify feed "red left" or "red right". The installer must be advised of the proper feed orientation on all ultra high performance antennas and proper polarization for plane-polarized antennas. DO NOT ORIENT "RED UP" OR "RED DOWN" LEFT OR RIGHT ONLY. REFER TO TEXT FOR DETAILS Vertical polarisation Horizontal polarisation Vertical polarisation Red Tape affixed here for UHX/HSX Antennas only (Above View of Feed Hub) Red Tape affixed here for UHX/HSX Antennas only (Above View of Feed Hub) Figure 9. Examples of Dual-Polarised Feed Positions with Bends in Horizontal Plane any specifications or warranties relating to products or services.
page 6 of 7 Dual-polarized, waveguide-fed antennas have both input flanges in the same plane to permit easier attachment of the waveguide, as shown in Figure 9. One input is rotated 90 within the feed to provide cross-polarization. Dual-polarized feeds for the following standard antennas must be positioned with the waveguide s in the vertical plane, as shown in Figure 10: PX6 series (except PX6-122/-127 series) PXL6 series (except PXL6-107 series) 5. Pressurize Line and Feed. Connect a dehydrator to the gas port of the flange connector closest to the transmitter or receiver. The dehydrator is used to purge the system of moisture and provide a constant supply of dry air at a specific guage pressure above atmospheric pressure. This supply is maintained to prevent moist air from entering the system and impairing performance. A source of nitrogen can be used instead of dry air. Remove the gas port plug on the connector at the antenna end of the transmission line and purge the line continuously until it is dry. Then replace the plug and pressurize the line. Top guy line 3 The dehydrator used depends on the pressure requirements of the waveguide transmission line and the feed. A guage pressure of 8 psi (55 kpa) is adequate for most systems. However, no more than 10 psi (70 kpa) should be used. Caution: Excessive pressure can damage the feed window. Some feeds may have lower maximum pressure ratings because they are limited by the size of the feed pressure window. Check to see if there is a pressure specification label on the feed to be certain that you are using the correct pressure - only those feeds that have a maximum rating of less than 10 psi are labeled with the maximum pressure rating. Example: For feeds connected to WR229 waveguide, use only 4 psi (28 kpa) pressure; the maximum pressure rating 5 psi ( 35 kpa). Rear view of feed hub Figure 10. Examples of Dual-Polarised Feed Positions with Bends in Vertical Plane (applies to specific antennas-see text ). 4. Connect Transmission Line. Remove the protective covers from the feed input flange and the connector flange of the transmission line. Connect the flanges together with screws, lock washers and nuts (if supplied), using the proper O-ring or O-rings. Finger-tighten all of the screws. Then tighten first the screws at or near the center of the long dimension of the flange and then those on the short dimension. Tighten the screws in pairs; that is, screws located 180 apart. If the gap between the connector flanges is not uniform after tightening, loosen the screws and retighten them. Transmission line installation normally starts at the antenna and proceeds to the transmitter or receiver. The lines must be anchored with hangers along the supporting structure to prevent any strain at flange connections. Refer to instruction bulletins supplied with transmission line for torque values. Feed Replacement Recommendations A. Replacement of Improved Hub Design Feed General Note. Some feeds have a feed horn, illuminator ring and waveguide s that cannot be passed through the 8-inch (203 mm) diameter opening in the mounting ring. When this is the case, the feed must be removed from the front side of the antenna. The following feeds cannot be removed from the rear side of the antenna. Single polarized feeds with WR229 waveguide Dual-polarized feeds with WR112 and larger waveguide When replacing a feed, you should also consider replacing the new parts included in the kit: mounting ring, vertex ring, vertex ring shim and guy wires. If these parts are to be replaced, they must be installed from the front side of the antenna as given in Steps 1, 2 and 3 for new installations. To remove the feed from the rear of the antenna for either replacement or inspection of the feed horn and window, proceed as follows. any specifications or warranties relating to products or services.
page 7 of 7 A.1. Remove Old Feed. Loosen the hub locking clamps, slide them toward the centre of the hub and finger tighten the nuts. Carefully push the feed hub slightly forward and slightly downward so that the spring tension of the guy wires holds the hub in place against the front surface of the mounting ring. Carefully remove the hub retaining ring from the inside of the mounting ring. Do not discard this ring as it will be reused. Push the feed hub slightly forward and allow it to pass through the mounting ring. Disconnect the guy wires to the front surface of the reflector so that they can be easily reached for reattachment. A.2. Feed Replacement (Improved Hub Design) Do not remove flange covers until you are ready to connect the feed to the feed lines. The flanges must remain clean and dry. B. Replacement of Old Style Feed with Feed of Improved Hub Design Replacement feeds are furnished with a mounting ring, guy wires and mounting hardware. Also included with these parts, some feeds will require either a vertex ring or a vertex ring and vertex ring shim which optimizes performance. Installation of the new vertex rings/vertex ring shim's, however,must be done from the front side of the antenna as given for a new feed installation - the old feed mounting ring and vertex ring shim(s) must be removed. If no vertex rings/vertex ring shims are required, most replacement feeds can be installed from the rear of the antenna (see General Note). Attach the mounting ring as given in Step 1 for new feed installation. Then complete the installation as given in step A.2. Attach the guy wires to the anchor ring of the new feed and guide the feed through the mounting ring. Push the feed hub forward and slightly downward so that the spring tension of the guy wires holds the hub in place against the front surface of the mounting ring. Apply a coating of 203233-2 corrosion inhibiting compound to the groove in the mounting ring. Insert the hub retaining ring over the groove in the mounting ring with the overlap ends positioned toward the top of the antenna. Then apply the compound to both sides of the hub retaining ring. Push the feed hub slightly forward and allow it to come through the mounting ring and rest against the hub retaining ring. Position the hub locking clamps on the mounting ring as shown in Figure 5 and finger-tighten the nuts. Then adjust the polarization (see Figure 8 and 9) and tighten the nuts, torque to...(see torque table 1 on page 7). any specifications or warranties relating to products or services.