1W UHF AMPLIFIER ASSEMBLY
PUB99-92 rev 1: June 19, 2000
92-5
1
W UHF Amplifier
7.0
BASIC
MAINTENANCE
Please note that the following are basic maintenance guidelines and general information and not all may be
applicable to your particular equipment.
7.1
GENERAL
When the transmitter was installed and commissioned it was in proper operating condition. During final
tests, all circuits were checked for optimum adjustment to ensure both peak performance and conservative
operation of components, and test results were recorded for future reference.
Given reasonable care and attention the transmitter will provide efficient and reliable service for many
years.
Experience indicates that equipment which is regularly and carefully maintained is far less likely to be
subject to sudden failure than that which is operated continuously without regard to basic maintenance
requirements. It is therefore desirable that a detailed preventive maintenance program be established to
ensure that the original efficiency and picture quality is maintained throughout the life of the equipment.
Preventive maintenance techniques do not necessarily involve extensive dismantling of the various
assemblies; on the contrary, this practice is to be discouraged unless a valid reason exists for doing so.
Preventive maintenance is more concerned with detailed physical inspection and the general observation
of the equipment during and after operation, to detect the presence of any abnormality which if not
corrected might later develop more serious proportions, resulting in operational failure.
In preparing any maintenance program, the frequency and scope of the inspections must be determined,
and to a great degree will be influenced by site location and the station's market parameters consequently
its hours of operation, equipment configuration, and technical personnel deployment. For example, is the
station on the air for 24 hours a day, are there main/standby transmitters, and are they attended or
unattended? In general, the following routines should form the basis of any maintenance program.
7.2
DAILY
At an attended site, the operator is afforded the opportunity to make daily or more frequent checks on the
equipment and thereby increase his/her familiarity with its operation. The "transmitter log" entries made
during these checks would include all meter readings, also any irregularity in performance, or in picture
quality, for later analysis. An unattended site where equipment is operated by remote control, and
monitored by telemetry and a high quality off-air receiver or demodulator located within the primary
coverage area at the studio site, can also be continuously checked for performance by studio technical
personnel, using VITS or VBI test signals encoded into the video signal vertical blanking interval.
7.3
WEEKLY
If the site is unattended, and VITS or VBI test equipment is not available, many broadcasters schedule
their operational tests and transmitter inspections to be performed once a week during weekend hours,
such as from midnight Sunday to six AM Monday, depending on their market conditions.
If there is an emergency alternator, it should be checked out completely, and run for at least an hour under
full load. The checking of this unit should include the condition of its battery, its ease of starting (and its
Winter starting enhancers such as block heater, battery warmer, fuel antifreeze), its engine oil level and
condition (see "Monthly" below), its radiator coolant condition and level; and its fuel tank should be topped
up. This simple check will serve as a reminder to order more fuel if necessary.