User's Manual

PINEAPPLE TECHNOLOGY, INC.

UT X1K W-A Ope rating a nd Se rvic e Ma nua l

Page 51

VIII — ADJ USTMEN T S AND T UNIN G

to transmitters.

VIII — ADJ USTMEN T S AND T UNIN G

The UTX1KW-A is basically an FCC Type Certiﬁ ed broadband transmitter with a few frequency selective

sub-assemblies:

A. MODULATOR — Instructions for making adjustments to the modulator are included in the Manu-

factures Instruction Manual

B. BPU1KW — Band Pass ﬁ lter comes adjusted to the channel as purchased. To change frequency

would require a tuning adjustment to the ﬁ 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 ﬁ 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 ﬁ lter, it becomes necessary to purchase a new

ﬁ lter. Replacement ﬁ lters and service is available from Pineapple Technology Inc.

C. U600LDV2 POWER AMPLIFIER MODULE — The U600LDV2 has three areas where adjustments

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 ampliﬁ ers are set to

500ma/device side or a total of 1 amp/device. This adjustment can be made on the bench by ﬁ 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 ampliﬁ er during this adjustment.

To adjust biases 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

ﬁ 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 Fixed tuned providing no

adjustments. Any tuning at this level is performed by the factory.

3. GAIN & PHASE MATCHING: Each U600LDV2 comes with a circuit for making Gain and