Specifications

5-18 888-2857-001 5/9/13
WARNING: Disconnect primary power prior to servicing.
Section 5 Maintenance and Alignments
Platinum VAX-C Series
NOTE:
If the Linear RTAC section is in BYPASS at this time, linear correction will not
be stored.
Linear Equalizer:
STEP 5 Set the linear RTAC mode to ADAPT via the POWER menu on the
VAX-C front panel LCD display or by using the VAX-C web browser to
navigate to Exciter Home > Setup > DUC/RTAC screen.
STEP 6 Verify that the linear RTAC attempt and success counters increment
about every twenty seconds.
STEP 7 Use a TV analyzer to measure the MER (DVBT, DAB) or EVM (ATSC).
STEP 8 Save this current linear correction in one of the four slots (See Storing
Precorrection Section 5.5.2).
STEP 9 Procedure complete.
5.5.1.1 Troubleshooting Precorrection
If the RTAC mode are set to ADAPT, but the Attempts counter does not increment
within thirty seconds, there is a problem with the feedback samples.
Check the signal levels at the PRE and POST-FILTER inputs on the back of the VAX-C.
They should be between -10dBm and +5dBm (optimum is 0dBm at the inputs on the
back of the VAX-C).
Check the RTAC levels on the VAX-C STATUS > RTAC GUI screen. The bar meters
should be green and the level should be just below the black 100% line.
Check that the exciter Home Screen shows ON in the upper left corner of the GUI
screen. If the exciter is OFF or MUTE, the corrections cannot be calculated.
5.5.2 Storing Precorrection
Follow this procedure to store the calculated RTAC correction values to VAX-C
memory.
STEP 1 Go to the RTAC - Stored Correction sets Screen, Figure 5-7.