Motorola BLE100 operation manual Testing Return Gain and Response, Completing the Test Procedures

4-4 Bench Testing

Testing Return Gain and Response

After configuring the return path, you can test the return bandpass to ensure compliance with specifications. When testing the return amplifier, remember that it is a flat amplifier. Therefore, the cable simulator must remain in the test set-up and must remain set to the same cable equivalent as in the forward sweep test. This provides an approximate indication of the frequency response, which you can achieve in the field.

To test for return gain and response:

1Reconnect the test equipment and switch the sweep input and sweep output leads of the BLE100 under test to be opposite of the connection shown in Figure 4-1.

2Remove the power block at the input port and replace the 20 A fuse at the output port (both illustrated in Figure 2-8) before you apply power.

3Re-adjust the test equipment to sweep from 4 MHz through the maximum return band frequency plus 10 MHz (Example — 50 MHz for S-split).

The expected response is flat. Any tilt, which is due to the return equalizer, must average out to a flat response in a cascade of amplifiers. A slope adjustment is not available in the return bandpass.

4Measure the gain at the maximum return band frequency (40 MHz for S-split).

The amplifier gain is the sum of: the measured gain, the insertion loss of the return cable equalizer at the maximum return band frequency, the insertion loss of the power combiner, any pads installed in either the input or output pad locations, plus the cable simulator loss at the maximum return band frequency. The measured gain must meet advertised specifications for the return amplifier.

Example:

14.0dB (measured gain)

+1.0 dB (equalizer insertion loss)

+1.1 dB (power combiner)

+0.0 dB (pads)

+4.6 dB (cable simulator at 40 MHz)

+20.7 dB (unit gain)

Completing the Test Procedures

The amplifier is now approximately tailored for a specific field location. Additional adjustments after installation are minor in nature. Re-install the fuse or power-block removed during testing.

Complete station records by recording pertinent information. Remove test-equipment connections and close the housing following instructions provided in Section 5, “Installation,” Closing the Housing.

BLE100 Installation and Operation Manual