Technical Manual
PINEAPPLE TECHNOLOGY, INC.
UTX5KW-A Operating and Service Manual
Page 54
VIII — ADJUSTMENTS AND TUNING
VIII — ADJUSTMENTS AND TUNING
The UTX5KW-A is basically an FCC Type Certied broadband transmitter with a few frequency selective
sub-assemblies. A list of these sub-assemblies are listed below and followed by general instructions where
applicable:
A. MODULATOR/UPCONVERTER — Instructions for making adjustments to the modulator are
included in the manufacturer’s instruction manual.
B. BPU5KW Band Pass Filter comes adjusted to the channel as purchased. To change frequency would
require a tuning adjustment to the lter. To perform this adjustment it is necessary to use a NETWORK
ANALYZER and a signal generator with necessary I/O Adaptors to connect to the lter. The Technician
performing this adjustment should be skilled in tuning Band Pass Filters. If the target frequency is
outside of the tuning range of the lter, it becomes necessary to purchase a new lter. Replacement
lters and service is available from Pineapple Technology, Inc.
C. U600LDV-2 POWER AMPLIFIER MODULE — The U600LDV-2 has three areas where adjust-
ments may be necessary over time or in the event of a frequency change. These areas are:
1. Bias adjustments: The LDMOS FET devices used in these pallet ampliers are set to 500ma/device
side or a total of 1 amp/device. This adjustment can be made on the bench by rst terminating the
input and output with 50 ohm terminations. Apply 31 volts DC to the PA using a power supply that
can provide a minimum of 15 amps. Note: a cooling fan will be necessary to cool the amplier
during this adjustment.
To adjust the bias’ it is best to turn all the bias adjust resistors CCW or to minimum on the pallet
being adjusted. Using a clamp on AMP Meter connected to the DC Feed terminal located on the DC
ISOLATION AND CURRENT MONITOR BOARD measure the current levels. The rst resistor is
increased to 500ma indicated on the Amp meter. Repeat this adjustment for each additional resistor
for reading of 1.0 A, 1.5 A, and 2.0 A. This will indicate that each device half is set to 500 ma.
This concludes the bias adjustment procedure. This adjustment should be made at any time when
a device has to be replaced. Normal bias ranges from 1.5 amps to 2.3 amps per pallet as indicated
on the ADP500/1000. DO NOT USE THE ADP500/1000 CURRENT READINGS FOR MAKING
BIAS ADJUSTMENTS.
2. PA PALLET RF circuit tuning: These circuits are broadband and xed tuned providing no adjust-
ments. Any tuning at this level is performed by the factory.
3. GAIN & PHASE MATCHING: Each U600LDV-2 comes with a circuit for making Gain and Phase
adjustments. This adjustment is xed tuned for the channel of this transmitter. Adjustment to this
circuit requires the following equipment:
• HP 8508A VECTOR VOLTMETER
• BIRD THRU LINE WATT METER
• SPLITTER
• 2ea DIRECTIONAL COUPLERS
• 2ea 500 watt terminations
• Component selection charts for resistors
• Component selection chart for capacitors
Component selection charts and setup block diagram provided as needed. Recommended tuning should be
within +/- 0.15 dB and +/- 3 degrees as measured on the HP 8508A.