Terrasat IBUC - Page 48

IBUC Operation Manual
Terrasat Communications, Inc.
Rev. A
5-3
TX IF Input Level Verification
If low or no TX output power is detected, start the troubleshooting by checking the input
to the IBUC. Use the following procedures:
Warning; DC power may be present on the cable so the use of a DC block is
recommended when performing the following steps.
- Check the TX Input Level displayed in M&C or disconnect the cable at the IBUC J1
(TX L-band) and use a spectrum analyzer to measure the power level of the L-band
signal at the output of the coaxial cable that connects to the IBUC at J1 (TX L-band).
The L-band signal level should be between –20 and –55 dBm. If it is not, check the
cable and modem output.
- If the L-band signal is good, check that the 10MHz-reference signal is between +3
and –12 dBm and is distortion free. If it is not, check the cable and modem output (or
IFU TX OUT).
- If the L-band and 10MHz signals are good check that the DC voltage level is within
range. For 12 watt and lower power units only the DC voltage may be on the L-band
IFL or from a separate power supply. For higher power units the DC voltage will be
on the DC cable that is connected to the IBUC J3 (DC Input). If it is not, check the
PSUI or modem (or IFU) power supply outputs and cables. The PSUI has a visual
indication when it’s turned on (green LED).
- If the L-band, 10MHz and DC voltage signals are good proceed to the IBUC TX
Output verification.
- Disconnect the spectrum analyzer from the coaxial cable.
IBUC TX Output Verification
This check assumes that the L-band, 10MHz and DC inputs are at the correct levels.
- TX Output level is monitored and displayed in the IBUC M&C.
- Alternatively, you may connect a waveguide to coax adapter and a 40dB high power
attenuator to the IBUC TX waveguide output.
- Measure the TX RF output with the spectrum analyzer connected at the waveguide
output. Ensure that the cable loss of the cable being used for the measurement has
been taken into account.
- The RF power should be between rated power and rated power –25 dB. If it is not,
the IBUC is defective and should be returned to the factory for repair.
- If the IBUC TX RF output measures good, check the waveguide, feedhorn and
antenna for proper operation.
Receive L-band Output Verification
If low or no RX output power is detected, start the troubleshooting by checking the
output of the LNB. Use the following procedures:
- Ensure that the 15-24VDC (LNB Bias) is present at the modem RX input (or IFU RX
IN) using a DVM. If it is not, check the cable and modem.
- Use a spectrum analyzer to ensure that the10MHz signal is present at the modem
RX input (or IFU RX IN). If it is not, check the cable and modem.