CHPA SERIES
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4-7
4.8 Verifying RF Output Level
After verifying the factory settings and test functions of the CHPA in Standby state, the next
step will be to place the CHPA in the Transmit state to verify the RF Output operation. (Refer to
Table 5-1 in Chapter 5.) Perform the following steps:
1.
Verify that STANDBY LED and LOCAL are indicated on the display; repeat steps 1-3 under
“Power-On Self-Test and Heater Time Display” if they are not.
2.
Verify that the RF Input and the RF Output are connected to a matched source and test load.
3.
Set the display to indicate RF settings in watts. To do this
a.
Press the SPECIAL button followed by the (decimal) button.
b.
Key in 03, the RF Inhibit selection will appear on Line 4.
c.
Press the FUNCTION button once—RF SETTING will appear on Line 4.
d.
Press either arrow key until Line 4 reads WATTS.
e.
Press the Line 3 button located below the display. Lines 3 and 4 will now display the
default meters (Line 3–Helix Voltage and Current; Line 4–Attenuator).
4.
Ensure that the attenuator is set to maximum attenuation.
a.
To quickly get to the attenuator setting adjustment, press the SPECIAL button followed
by the . (decimal) button.
b.
Key in 01, the display will change to attenuator input.
c.
Key in 25.0 to set the attenuator to its maximum.
(The attenuator may be set by either keying in a desired attenuator setting directly followed by
the ENTER button or pressing either arrow key to adjust the attenuator setting in 0.1 dB
increments.)
5.
Press the TRANSMIT pushbutton. The CHPA will transition from the Standby state (the
STANDBY LED extinguishes), through the Beam On Sequence (BONS) state (TRANSMIT
LED flashes), to the Transmit state (TRANSMIT LED is solidly lit).
Note: At this point of the procedure, the Low RF Alarm may have tripped.
This is indicated by LoRF on Line 2 of the display.
6.
Slowly increase the RF output by repeatedly pressing the down arrow key to decrease the
attenuator setting in 0.1 dB increments until the output reaches 600(500W for the 600W DBS
Band unit 415W for the 500W DBS band unit) as indicated on the front panel. Write down
this attenuation value because it will be used later.
a.
The FAULT LED should remain off.
b.
While adjusting the RF power, LoRF or HiRF (Low RF Alarm or High RF Alarm) should
not appear on Line 2 of the display. Recheck the alarm settings if necessary.