Shively Labs 6812B, Instruction Manual Installation, Operation, & Maintenance

Page 1: ...Circularly Polarized FM Broadcast Antenna Model 6812B Instruction Manual Installation Operation Maintenance ...

Page 2: ...omponents Our technical staff has a wealth of experience in the broadcast industry and is standing by to serve you in any way This manual is intended to give you a basic understanding of your antenna its proper and safe installation startup and operation and troubleshooting and maintenance information to keep it working satisfactorily for years to come Please have everyone involved with the antenn...

Page 3: ...this manual in its entirety before beginning installation of your antenna Failure to follow the installation and operation instructions in this manual could lead to failure of your equipment and might even void your warranty ...

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Page 5: ...e exploded view 6 Installing the interbay cable harness 6 Figure 6 Installation of top and bottom bays 7 Figure 7 Wrapping and securing the interbay cables 8 Figure 8 Proper and improper application of splicing tape 9 Chapter 3 Installing the De icer System if applicable 11 Precautions 11 De icer system description 11 Figure 9 De Icer electrical schematic diagram 12 Table 4 De Icer specifications ...

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Page 7: ...spect the tower and review the installation drawings before the full rigging crew arrives If design problems are found contact Shively Labs immediately Pay particular attention to Frequency of the antenna Freedom from interference by gussets leg flanges guy wires and their attachment points tower face members obstruction lights and other components Compatibility of coax connectors and antenna inpu...

Page 8: ...Wave Spacing Half Wave Spacing Special Spacing 88 98 MHz Low Band 108 in 2 74 m 63 1 2 in 1 61 m 11803 x spacing frequency round to closest 1 8 98 108 MHz High Band 98 in 2 49 m 57 in 1 45 m 11803 x spacing frequency round to closest 1 8 Table 2 Torque specifications Hardware size Torque dry Torque lubricated 1 4 20 radome flanges 75 2 in lbf 8 5 N m 63 9 in lbf 7 2 N m 5 16 18 1 5 8 EIA flanges 1...

Page 9: ...pipe installation Follow these guidelines a To ensure good electrical contact between the support pipe and the tower remove the tower paint and any rust at the support pipe mount locations before installing the mounts After installing the mounts be sure to touch up the paint where you removed it b Starting at the top of the support pipe mark the location of each bay in accordance with the installa...

Page 10: ...adiator CAUTION Radiators are stenciled with their respective bay numbers bay 1 is the topmost bay Install the radiators in accordance with their match mark ings If you don t the antenna may not perform as expected Installation procedure a Remove any paint or corrosion on the support pipe where the formed mount channel will be located to ensure good electrical contact b Position radiator 1 at the ...

Page 11: ...5 Antenna Installation Figure 3 Installation of radiator without radome exploded view Figure 4 Radome backplate installation ...

Page 12: ...sion Figure 5 Installation of radiator with radome exploded view Installing the interbay cable harness CAUTION Tighten the connector nuts finger tight only Using pliers or other mechanical means to tighten the connectors may damage them CAUTION The minimum bend radius of RG 214 cable is 2 inches 50 8 mm a Locate the end of the harness that is marked Bay 1 Form the cable as shown in Figure 6 and at...

Page 13: ...e wrapped in a particular fashion as shown in Figure 7 on page 8 DO NOT make a continuous spiral wrap around the pipe as shown on the left Doing so will ruin the VSWR of the antenna d Wrap and secure the interbay feedline cable as follows Figure 7 CAUTION Do not put too much tension on the feedline just make it snug 1 Between each pair of antenna bays loosen the connectors at both ends just enough...

Page 14: ...n and around the area where the connection is made Make sure the joint is fully covered but do not seal up against the bulkhead plate 4 Inspect the connection carefully ensuring that the joint is fully sealed If more splicing tape is needed simply add it to the existing wrap It adheres well to itself f Stretch tape and apply half lapped to form a smooth void free splice Wrap tightly in and around ...

Page 15: ...tallation Figure 8 Proper and improper application of splicing tape CAUTION To prevent damage secure all coax to minimize wind induced motion and chafing h Tie all coax to the mounting pipe to prevent it from damage ...

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Page 17: ... electrical schematic Figure 9 on page 12 Electrical specifications Table 4 on page 13 Bay junction box Figure 10 on page 14 Thermostat readings Table 5 on page 15 Your system may also include specially ordered items such as a ground mounted main control box a power cable extending up the tower or a tower mounted dual setting thermostat Dual setting thermostat CAUTION Remember that conditions may ...

Page 18: ...nes NOTE A liquid tight conduit con nector 3 8 conduit size by 1 2 hub size for the harness entry to the tower junction box is packed loose with the de icer harness NOTE Shively recommends the use of shielded braided polyethylene covered wire or rubber sheathed flexi ble metal conduit or rigid conduit and weather tight fittings at all junctions ...

Page 19: ...t the antenna s de icer harness to the main power c Using tie wraps secure the entire length of the de icer harness to the RF feedline at about 24 60 cm intervals Run the ten foot de icer pigtail along a feedline mount to the tower junction box and secure it to the mount and the tower Table 4 De Icer specifications Heater Leg Resistance Heater Leg T1 or T2 Current Draw amps 1 Bay 203 0 6 2 Bay 101...

Page 20: ... taking resistance readings Otherwise read ings may be affected by other components a Before you connect the thermostat measure the resistance across the thermostat circuit and from it to ground to ensure that there are no short circuits Thermostat readings should be as shown in Table 5 on page 15 b Mount the thermostat near the antenna and connect the thermostat leads to points S1 and S2 in the c...

Page 21: ...rt circuit Resistance infinite ohms open circuit Leg to Ground Any Defective thermo stat or shorted leads OK Leg to Leg Above about 38 F 3 3 C Defective thermo stat or shorted leads OK Between about 10 and about 38 F 6 7 to 3 3 C OK Defective thermo stat or broken leads Below about 10 F 6 7 C Defective thermo stat or shorted leads OK ...

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Page 23: ...lowing items have been done The antenna system has been installed in accordance with this manual and the installation drawing The de icer system if purchased has been checked out in accor dance with Chapter 3 All radiators are operating and VSWR is low System sweep data if desired have been recorded Check the system out as follows a Bring up RF power slowly and observe transmitter readings stabili...

Page 24: ...e icer control system If you have the Shively Labs de icer control box and dual setting thermostat you have the choice of manual or automatic operation There are three switch settings AUTOMATIC OFF and MANUAL When the switch is set to AUTOMATIC the thermostat turns the heaters on and off according to the temperature When the switch is set to OFF the thermostat is overridden and the heaters will st...

Page 25: ...spect radomes for cracks and plugged drain holes Re tighten all hardware hose clamps and U bolts to installation specifications Inspect hose clamps and U bolts carefully for signs of wear or fatigue caused by vibration or tower movement Paint The radiators should never be painted a coating of paint affects VSWR and they need no surface protection since they are made of copper and brass This includ...

Page 26: ...s the impedance match between the transmitter and the antenna sys tem Possible causes include Wrong antenna for the application and frequency Occasionally incorrect frequency information is provided to Shively or an antenna designed for another application is used Defective cable connector in the cable harness Incorrect assembly of the antenna for example an upside down radiator radiators out of s...

Page 27: ...g It is important to recognize however that apparent changes in coverage may be due to subjective factors or faults of the receiving equipment Before doing more than checking the VSWR be sure that an actual coverage change has occurred ...

Page 28: ...eshooting 22 Sample maintenance log DATE DE ICER CURRENT or resistance VSWR OBSERVATIONS Visual Inspection of Antenna Obstruction Lighting Hard ware Checked Tower Repairs Accomplished etc BLACK b neut NEUT red bl RED r neut ...