Return Field Testing - C-COR Flex Max901e Equipment Manual

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Return Field Testing

This procedure verifies that the amplifier:
The following procedure requires the use of a signal generator and a signal level meter (SLM). A
more comprehensive test that sweeps the entire bandwidth with an appropriate sweep
generator/receiver may be required, especially if response problems at specific frequencies are
suspected.
To field test the return path
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1502154 Rev D
Calculate the true amplifier gain by subtracting the input high balancing carrier signal level
measured at Port 1 from the output signal levels measured in Step 3. The difference should
equal the operational gain of the amplifier (at the balancing carrier) minus insertion losses
from accessories installed in the forward path. Refer to Use Of Accessory Tables on page
D-1 to determine insertion losses at the high carrier frequency. Replace the RF module if
the amplifier gain measured at any port is outside of acceptable tolerance.
Reset the ALC/MAN switch to ALC.
Adjust the ALC SENSITIVITY control as described in Factory-Shipped Configurations for
Flex Max901e Trunk and Bridger Amplifiers on page 5-9.
CAUTION RF signal levels greater than +90 dBmV (1 return NTSC channel) injected into
a forward output testpoint can damage amplifier active components. Derate maximum
input level according to actual channel loading (for example, +82 dBmV @ 6 NTSC
channel loading) (+82 dBmV = +142 dBµV).
is balanced to the correct return signal levels
delivers the specified gain to return RF signals
Note All measured signal levels must be temperature compensated to a common
temperature before they can be accurately compared. Refer to Temperature
Compensation on page 5-6 for information.
Note Do not terminate the unused port testpoint as it can affect testpoint accuracy.
Connect the signal generator to:
the internal/external PORT 4 FWD O/P TP for Trunk amplifiers
the internal/external P2/P3 FWD O/P TP for Bridger amplifiers
Set the signal generator to output the correct Return High Balancing Carrier level (plus
20dB to compensate for testpoint loss) at the proper frequency.
Connect an SLM to the PORT 1 REV O/P TP and measure the output signal level of the
Return High Balancing Carrier. Compare the current level to the measurements made when
the amplifier was previously balanced. If the current measurement is unacceptable, verify
that the proper accessories are still installed in all return plug-in locations and replace any
accessories not in compliance with the Amplifier Data Sheet. If necessary, rebalance the
amplifier.
Troubleshooting 6-5
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