User's Manual

61-38-05 UserMan page 32 of 38
TXRX Systems Inc. Manual 7-9408-1.2 07/25/05 Page 32
generally cause noticeable gain reductions to other
channels on the system and may also exceed the
maximum input level.
Connect the positive lead of a multimeter set to
measure DC voltage on a 0-20 volt scale, to the
OLC voltage test point on the OLC assembly. Fig-
ure 8 shows the location of the test point on the 3-
6280 OLC assembly. The negative lead of the mul-
timeter is connected to the chassis. (The black test
probe jacks on the voltage regulator assembly are
convenient for this). Compare the measured volt-
age readings with those on the OLC test data
sheet to see what degree of overload, if any, is tak-
ing place. Refer to the section in this manual titled
"Gain Reduction Methods" to correct an excessive
overload condition.
MAINTENANCE AND REPAIR
Signal boosters manufactured by TX RX Systems,
Inc. can function reliably for 10 or more years with
little or no maintenance. However, if the amplifiers
are subjected to excessively high signal levels,
power surges or lightning strikes, failures may
occur. The following procedures may be followed
for detecting a malfunctioning unit or as part of a
periodic maintenance program.
1) Heat sinks for the power amplifiers should be
cleared of dust and debris.
2) Inspect the units to see that the LED DC indica-
tors are lit (remove any dust or debris that may
obscure the LEDs). This will verify that DC
power is flowing properly. Check all hardware
for tightness.
3) Compare system performance to initial perfor-
mance levels measured when the system was
first installed. The lack of signal can be traced to
a malfunctioning amplifier by progressive signal
monitoring from the output (far end) to the input
end of the system noting the area where the
signal returns to normal level. The next amplifier
toward the output end of the system will proba-
bly be the one that failed.
or
Measure the gain of each branch at any conve-
nient frequency in the working frequency bands
to verify that the gain specifications are being
met. If the gain values fall below that specified
for a given model check the following:
A) Open the signal booster cabinet and inspect for
any loose or broken connections or cables, and
repair as necessary.
B) Measure the output of the power supply and
power regulators to see that the proper operat-
ing voltage is being maintained.
C) If the operating voltage is proper but the gain is
still low, measure the gain of each amplifier
stage until the one with low gain is isolated.
Replace a low gain amplifier with a new ampli-
fier stage to correct the problem.
RECOMMENDED REPLACEMENT PARTS
One each of the following: Power Amplifier Assem-
bly 3-11792, 1stg/3stg Amplifier Assembly 3-
11423, Voltage Regulator Assembly 3-5969, and
Power Supply Assembly 3-15503.
CONVERSION CHART
A Power in Watts to dBm conversion chart is
included on the following three pages. Most of the
setup and conversion procedures refer to power
levels in dBm more often than in Watts. This is
much more convenient when dealing with the
power levels and gain figures of signal boosters.
The chart allows easy conversion between the two
scales when necessary.