5.6.8.3
Air Flow Monitor Circuits
Set the Air Flow Monitor circuits on the Driver Encoder/Temp
Sense Board as follows:
NOTE
For all adjustments and verifications, allow the air sensor at
least one minute to stabilize. Fans are easily shut off by removing
two of the three fuses mounted near each fan in the Output Net-
work Compartment.
a. Operate the transmitter for a minimum of 15 minutes at
full power at 100% modulation with a 1 kHz tone. All fans
should be operational.
b. With the DRIVER COMPARTMENT DOOR OPEN, ad-
just the AIR FLOW CAL adjustment R98 for a +2.25 VDC
reading at TP11.
c. Close the Driver Compartment door and verify that this
reading increases to +2.5 VDC (+/- 0.05 VDC).
WARNING
ENSURE ALL PRIMARY AC VOLTAGE HAS BEEN REMOVED
FROM TRANSMITTER AND A GROUNDING STICK IS USED TO
GROUND ALL POINTS WHERE AC OR RF POWER HAS BEEN
APPLIED BEFORE PROCEEDING WITH THE FOLLOWING PRO-
CEDURE.
d. Remove the left rear access panel from the Output Network
Compartment to expose the four cooling fans.
e. Remove any two of three fuses from one of the fans.
f. Replace the left rear panel on the Output Network Com-
partment.
g. Reapply primary AC voltage and turn the transmitter ON
at HIGH power.
h. Modulate at 100% with a 1 kHz tone.
i. Observe that the transmitter will remain ON with ALL
DOORS CLOSED.
j. The AIR INTERLOCK LED on the ColorStat™ should
turn AMBER after a few minutes of operation.
k. The voltage at TP11 on the Driver Encoder/Temp Sense
Board should now be b2.8 and +3.1 VDC.
WARNING
ENSURE ALL PRIMARY AC VOLTAGE HAS BEEN REMOVED
FROM TRANSMITTER AND A GROUNDING STICK IS USED TO
GROUND ALL POINTS WHERE AC OR RF POWER HAS BEEN
APPLIED BEFORE PROCEEDING WITH THE FOLLOWING PRO-
CEDURE.
l. Remove the left rear access panel from the Output Network
Compartment to expose the four cooling fans.
m. Remove any two of three fuses from a second fan.
n. Replace the left rear panel on the Output Network Com-
partment.
o. Reapply primary AC voltage and turn the transmitter ON
at HIGH power. Modulate at 100% with a 1 kHz tone.
p. The transmitter should shut OFF within 15 minutes and
the AIR LED on the ColorStat™ panel should turn RED.
WARNING
ENSURE ALL PRIMARY AC VOLTAGE HAS BEEN REMOVED
FROM TRANSMITTER AND A GROUNDING STICK IS USED TO
GROUND ALL POINTS WHERE AC OR RF POWER HAS BEEN
APPLIED BEFORE PROCEEDING WITH THE FOLLOWING PRO-
CEDURE.
q. Remove the left rear access panel from the Output Network
Compartment to expose the four cooling fans. Replace the
fuses and the rear panel. Restore primary AC voltage to the
transmitter.
5.6.9
Switch Board/Meter Panel (A31)
There are three adjustments on the Switch Board/Meter Panel.
5.6.9.1
Forward Power Calibrate R14
This adjustment is calibrated at the factory by measuring trans-
mitter power output in a calorimetric dummy load. This calibra-
tion adjustment should not be changed unless some means of
accurately measuring transmitter power is available. If no exter-
nal RF Power measuring device is available and the Switch
Board/Meter Panel or Power Meter is replaced, a close approxi-
mation of output power can be determined by using the efficiency
factor of the transmitter, number of PA Modules ON and PA
Current as recorded on the Test Data sheet. Forward Power
Calibration adjustment R14 should then be adjusted for the
correct power reading on the front panel meter.
5.6.9.2
Reflected Power Calibrate R13
Once the Forward Power reading has been calibrated, operate the
front panel to the REFLECTED position and move P1 and P2 on
the Output Monitor board to the 1-3 position. The Power Meter
will now read Forward Power on the Reflected Power position.
Adjust R13 for the correct power reading on the Power Meter.
Return P1 and P2 on the Output Monitor board to the 1-2
position.
5.6.9.3
PA Volt Meter Calibrate R8
WARNING
ENSURE ALL PRIMARY AC VOLTAGE HAS BEEN REMOVED
FROM TRANSMITTER AND A GROUNDING STICK IS USED TO
GROUND ALL POINTS WHERE AC OR RF POWER HAS BEEN
APPLIED BEFORE PROCEEDING WITH THE FOLLOWING PRO-
CEDURE.
a. Open the Driver Compartment door and locate the Driver
Supply Regulator. Remove the clear protective cover.
b. Attach the positive lead of a volt meter capable of reading
+250 VDC to where wire #6 connects to the PA Power
Supply discharge switch S1. Attach the negative lead to
transmitter ground.
c. Replace the Driver Supply Regulator clear protective
cover.
d. Apply primary AC voltage to the transmitter.
e. Operate the transmitter at normal operational power.
f. Adjust R8 on the Switch Board/Meter Panel so the front
panel multimeter PA VDC reading corresponds
to the reading on the external meter.
DX-25U
5-14
888-2297-002
Rev. Z1: 06-02-00 Additional info to ECN 46105
WARNING: Disconnect primary power prior to servicing.
