Assembly Instructions Chapter 3

ManualsBrandsUBS-Axcera ManualsElectronics10,000-watt UHF solid state television transmitter

10-kW UHF Transmitter with Chapter 3, Installation and

Feedforward Drive Setup Procedures

840A, Rev. 0 3-1

Chapter 3

Installation and Setup Procedures

There are special considerations that

need to be taken into account before the

840A can be installed. For example, if the

installation is completed during cool

weather, a heat-related problem may not

surface for many months, suddenly

appearing during the heat of summer.

This section provides planning

information for the installation and set up

of the transmitter.

3.1 Site Considerations

The 840A transmitter requires two main

AC input lines, a 3-phase 208/240 VAC,

60 Hz input of at least 100 amp rating

that connects to the high-voltage power

supply assembly and a single-phase

208/240 VAC, 60 Hz input of at least 40

amp rating that connects to the

exciter/driver assembly. Make sure that

the proposed site has the necessary

voltage requirements.

The cabinets should be positioned with

consideration given for adequate air

intake and exhaust. In addition,

installation planning should take into

account the amount of space required for

the opening of the front of the metering

control panel on the 10-kW amplifier; the

opening of the rear doors on the 10-kW

amplifier and exciter/driver cabinets;

access to the trays, including sliding

them out for testing; the main AC hook-

up to the high-voltage power supply

assembly; and the installation of the

output transmission line, including the

trap filters and the directional coupler.

The 10-kW amplifier cabinet contains a

tube cavity air exhaust stack that is a

10.5-inch chimney mounted on the roof

of the cabinet. Forced air flows though

this chimney from the blower assembly

that cools the tube mounted in the cavity

assembly (1,100 CFM at 30° C rise).

The 10-kW amplifier cabinet also has two

exhaust fans, rated at 240 CFM, mounted

in the top cover assembly of the cabinet.

Air intake for the tube cavity blower

assembly is through the large filter

mounted on the bottom rear of the

cabinet.

The high-voltage power supply cabinet

has two exhaust fans, each rated at 550

CFM, mounted in the top cover assembly

of the cabinet. Air intake for the cabinet

is through the two filters mounted on

each side of the cabinet.

The 840A is designed and built to provide

long life with a minimum of maintenance.

The environment in which it is placed is

important and certain precautions must

be taken. The three greatest dangers to

the transmitter are heat, dirt, and

moisture. Heat is usually the greatest

problem, followed by dirt, and then

moisture. Over-temperature can cause

heat-related problems such as thermal

runaway and component failure. Each

amplifier tray in the transmitter contains

a thermal interlock protection circuit that

will shut down that tray until the

temperature drops to an acceptable level.

A suitable environment for the

transmitter can enhance the overall

performance and reliability of the

transmitter and maximize revenues by

minimizing down time. A properly

designed facility will have an adequate

supply of cool, clean air, free of airborne

particulates of any kind, and no

excessive humidity. An ideal environment

will require temperature in the range of

40° F to 70° F throughout the year,

reasonably low humidity, and a dust-free

room. It should be noted that this is

rarely if ever attainable in the real world.

However, the closer the environment is

to this design, the greater the operating

capacity of the transmitter.

Summary of content (14 pages)

PAGE 1
0-kW UHF Transmitter with Feedforward Drive Chapter 3, Installation and Setup Procedures Chapter 3 Installation and Setup Procedures There are special considerations that need to be taken into account before the 840A can be installed. For example, if the installation is completed during cool weather, a heat-related problem may not surface for many months, suddenly appearing during the heat of summer. This section provides planning information for the installation and set up of the transmitter.
PAGE 2
10-kW UHF Transmitter with Feedforward Drive Chapter 3, Installation and Setup Procedures The fans and blowers designed and built into the transmitter will remove the heat from within the trays, but additional means are required for removing this heat from the building. To achieve this, a few considerations should be taken into account. The first step is to determine the amount of heat to be removed. There are generally three sources of heat that must be considered.
PAGE 3
10-kW UHF Transmitter with Feedforward Drive Chapter 3, Installation and Setup Procedures transmitter under certain conditions. 3. Do not isolate the front of the transmitter from the back with the thought of air conditioning only the front of the unit. Cooling air is drawn in at the front of all transmitters and in the front and back of others. Any attempt to isolate the front from the rear will adversely affect the cooling air flow. 4.
PAGE 4
10-kW UHF Transmitter with Feedforward Drive 12. Regular maintenance of the filters, if used, can not be overemphasized. 13. Tube transmitters should not rely on the internal blower to exhaust cooling air at elevations above 4000 feet. For external venting, the air vent on the cabinet top must be increased to an 8" diameter for a 1 kW transmitter and to 15" for a 10-kW transmitter.
PAGE 5
10-kW UHF Transmitter with Feedforward Drive Chapter 3, Installation and Setup Procedures 3.2 Unpacking the Cabinets and Trays Remove the straps that hold the exciter/amplifier cabinet to the shipping skid and slide the cabinet from the skid. Remove the plastic wrap and foam protection from around the cabinet. Do not remove any labeling or tags from any cables or connectors, as these are identification markers which make reassembly of the transmitter much easier.
PAGE 6
10-kW UHF Transmitter with Feedforward Drive Chapter 3, Installation and Setup Procedures connectors, as these are identification markers that make assembly of the transmitter much. Open the metering control panel and the rear door of the 10kW amplifier. Inspect the interior for any packing material and carefully remove any that is found. other end through the top of the amplifier cabinet to the bottom of the tube cavity.
PAGE 7
10-kW UHF Transmitter with Feedforward Drive Chapter 3, Installation and Setup Procedures 208/240 VAC 3-phase input service. The primary and secondary terminals of the transformer are clearly labeled for the reconnection of the wires. primary connections of the high-voltage transformer. There are additional taps located on the high-voltage transformer to accommodate different line voltage inputs. The taps that are used are chosen at the site in order to attain a plate voltage output of 5500 volts.
PAGE 8
10-kW UHF Transmitter with Feedforward Drive Chapter 3, Installation and Setup Procedures the dolly tray. Reconnect both of these cables. the connected side at (A8-S11-E and F) the high-voltage interlock switch of the 10-kW amplifier to the high-voltage power supply assembly. After the two wires are fed through the conduit, connect the black ground wire to the chassis ground bolt labeled High-Voltage Power Supply RTN on the high-voltage power supply.
PAGE 9
10-kW UHF Transmitter with Feedforward Drive Chapter 3, Installation and Setup Procedures 3.9 Main AC Connections The AC feeds for the 840A 10-kW transmitter consist of two main circuits as described in Table 3-1. Caution: Check that all circuit breakers are off (Down) before making the main AC connections. Table 3-1.
PAGE 10
-kW UHF Transmitter with Feedforward Drive assembly by putting a firm, even downward pressure onto the top of the tube. The tube puller should be mounted onto the right, front corner of the tube cavity assembly. Caution: Do not turn or twist the tube while seating it. This will damage the finger stock. Snugly replace the upper anode assembly. After the cover is seated, the 6-mm hex bolts must be tightened to hold it in place. 3.
PAGE 11
10-kW UHF Transmitter with Feedforward Drive Chapter 3, Installation and Setup Procedures used for the automatic turn-on and shut down of the transmitter (translator control mode). The initial turn-on of the 10-kW amplifier assembly should begin by first applying AC power to each cabinet, in sequence, beginning with the high-voltage power supply and then the 10-kW amplifier. The high voltage that operates the 10-kW amplifier is supplied by the separate high-voltage power supply assembly.
PAGE 12
10-kW UHF Transmitter with Feedforward Drive Chapter 3, Installation and Setup Procedures Operating Status LED will light, indicating that bias is present at the tube. Open the hinged door of the metering control panel and verify that the status of the LED indicators on the control logic board (1137-1402) is as shown in Table 3-3. Table 3-3.
PAGE 13
10-kW UHF Transmitter with Feedforward Drive The following front panel operating status LEDs should also be illuminated: Blower, Filament, Bias, High Voltage, and Screen. The RF Present will remain off until the exciter/amplifier assembly is enabled. Chapter 3, Installation and Setup Procedures Move the Operate/Standby switch to the Standby position and observe the off cycle of the 10-kW amplifier. The front panel command status LED sequence should occur as shown in Table 3-4. Table 3-4.
PAGE 14
10-kW UHF Transmitter with Feedforward Drive mounted toward the rear of the single UHF exciter/amplifier cabinet. Also switch on the circuit breakers for the 250-watt amplifier trays. Turn the Operate/Standby switch on the exciter to Standby and the Auto/Manual switch on the UHF exciter to Auto. Normal operation of the transmitter is with the switch in Automatic. Automatic operation of the exciter uses the video input to the exciter as an Operate/Standby switch.