3
6
4
3.4
Alignment:
3.4a
UHF Notch Filter:
1.
Place the Amplifier Drawer POWER ON switch to off. Disconnect the input cable from the
Notch Filter and connect the filter’s input directly to the sweep generator's RF output.
2.
Place the RF Detector directly on the RF OUTPUT connector (J2) of the transmitter.
3.
Tune the sweep generator to the center frequency of the transmitter's output channel
employing a 20MHz sweep width display on the oscilloscope. Display the 1MHz markers.
4.
The filter adjustments are the two threaded rods located on the short side of the filter
accessible through the left side panel toward the rear of the drawer. If they are not marked,
slowly adjust one and observe which notch moves on the scope and set accordingly. Do not
switch the positions of the individual notches.
Set the lower notch to (Visual Carrier Frequency
!
4.5MHz).
Set the upper notch to (Aural Carrier Fre 4.5MHz).
The visual carrier frequency for the appropriate UHF channel can be found in
Section 4, the Data Pak, or in Table 2
6
1.
5.
Remove the sweeper cable from the filter input and the RF Detector from the drawer output.
Replace the Notch Filter input cable.
3.5
TTU100FA Transmitter Power Calibration:
To ensure proper transmission, the output power level and % Power Meter calibration should be
checked once every year. With the meter switch in the FWD position, the % Power Meter has been
factory calibrated for 100% with the transmitter providing 100 watts peak visual and 10 watts
average aural. The following calibration procedure assumes that the visual carrier has 87.5% video
modulation and 0% average picture level (APL). In the following steps, the power levels stated are
those expected at the output of the transmitter. Therefore, when measuring these power levels as
shown in Figure 3
6
6, be sure to take into account the 30dB factor provided by the attenuator. Power
levels at 50% APL (stair steps) are included in brackets following the power levels at 0% APL (SYNC
only).
3.5a
Forward Power:
1.
With the TTU20F in STANDBY and the TUA100FA Amplifier off (POWER ON circuit breaker
down), set up the test equipment as shown in Figure 3
6
6.
