User's Manual

PINEAPPLE TECHNOLOGY, INC.
UTX2.5K ULTRA Operating and Service Manual
VII -- ROUTINE MAINTENANCE
V
II --- ROUTINE MAINTENANCE (Page 1 of 2)
The following KEY MAINTENANCE AND PERFORMANCE CHECKS should be made monthly or mor
e
frequently in some environments where dust and rodents are problems. Pineapple Technology, Inc.
recommends that the station provide a data log book to maintain these records.
DANGER: SOME OF THE RECOMMENDED TESTS REQUIRE THAT THE TRANSMITTER BE
OPERATING IN NORMAL MODE. THIS PROCEDURE MUST BE PERFORMED BY A
BROADCAST ENGINEER. MORE THAN ONE PERSON SHOULD BE PRESENT IN CASE OF A
N
ACCIDENT REQUIRING ASSISTANCE. COMMUNICATIONS TO EMERGENCY SERVICES SHOULD
BE AVAILABLE
.
TRANSMITTER
● This is an integrated 2.5kW transmitter and is built around three (3) PA1K amplifier assemblies
located in two MFA2PA mainframes. (One mainframe only holds one (1) PA1K)
● Record the transmitter forward and reflected power on the watt meter provided with the transmitter.
This measured value will vary with picture content.
● Using the ADP500 and PAS3 record currents for each power LDMOS device in the transmitter.
The absolute measured value will vary with picture content so this is best performed with a fixed
signal such as SMPTE BARS, however, relative measurements are adequate to indicate a
problem at the power device stage. (See operating instructions for ADP500 and PAS3 for more
details).
● (OPTIONAL) When the transmitter is first put into service it is a good idea to go through each PA
stage and record the static bias level (NO RF DRIVE). This is done by selecting the desired
PA and using the PA INHIBIT switch. When this switch is activated, the PA drive is turned of
f
and the bias current can be measured. This is a momentary switch because when it is
activated, the PA drive is removed from all the PA's in one half of the transmitter and the outpu
t
power will be reduced to nearly zero (0) watts. THIS IS THE BEST METHOD TO USE WHEN
TROUBLESHOOTING A POSSIBLE BAD POWER TRANSISTO
R
.
● Record the voltage and current measurements displayed on the AUX meter.
● Carefully inspect RF Output coaxial cables for excessive heating or discoloration.
● Check DC Power connections on shunt panels and power supplies for over heating which
could indicate the hardware needs attention.
● Check DC Connections on the PA rear panel.
● Remove and clean the air filters located on the front panel of each MFA2PA mainframe assembly.
It is safe to remove the filter while the transmitter is operating. The filters may be cleaned with
a light detergent and dried completely before re-installing. Spare filters are available fro
m
Pineapple Technology, Inc. Request Part Number P/N 990199 when ordering.
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