500 WATT RADIOBEACON TRANSMITTER
ND2000A-02x-xx0
Page 5-2
15 January 2005
5.3.1
TEST/ADJUSTMENT
TEST
EQUIPMENT:
The following test equipment is
required to perform the functional test/adjustment
procedures. Refer to table 1-3 for additional
information regarding test equipment identification
and/or specifications.
-
Precision, 50-ohm, resistive, dummy load, rated
at 1000 watts
- Digital
multimeter
-
Audio signal generator
- Frequency
counter
-
Variable dc power supply
- Oscilloscope
- Stopwatch
- Variac
5.3.2
TEST/
ADJUSTMENT
PRE-
REQUISITES:
The following pre-requisites must be
completed prior to performing any of the following
procedures:
(a) Verify the ac power voltage is within five
percent of the voltage used to select the primary
winding taps of power transformers A7T1 and
A8T1.
(b) If the RF drive source is generated by a fixed
frequency crystal oscillator PWBs A4A3 and
A5A3, verify the PWBs have been set up as
detailed in paragraph 3.9.2.1.
(c) If the RF drive source is generated by a
frequency synthesizer PWBs (A4A3 and
A5A3), verify their switch settings have been
set to provide the desired frequency as detailed
in paragraph 3.9.2.2.
(d) Verify the pre-installation for keyer PWBs
A4A1 and A5A1, has been completed as
detailed in paragraph 3.9.3.
(e) Verify the appropriate primary winding taps of
power transformers A7T1 and A8T1 have been
selected and connected as detailed in paragraph
3.9.4.
(f) Verify harmonic filter A9's inductor taps and in-
circuit capacitors have been selected and
connected, for the assigned carrier frequency, as
detailed in paragraph 3.9.5.
(g) Connect the transmitter's RF output to a
precision, 50-ohm, resistive dummy load that
has provision to accurately display the RF
power being applied to it and is rated at a
minimum of 1000 watts.
(h) Extend exciter modules A4 and A5, from the
transmitter cabinet, to a position that allows
access to
O/P POWER
potentiometer A4A2R48
and A5A2R48.
(i) Set
O/P POWER
potentiometers A4A2R48 and
A5A2R48 fully counter clockwise.
NOTE
RF CURRENT ALARM
lamp should be on when the
transmitter is turned on and the RF output is cutback
to zero watts (
O/P POWER
potentiometer A4A2R48/
A5A2R48 set fully counter clockwise).
(j) Set
PWR TRIM - LOCAL
potentiometers A4R5
and A5R5 fully clockwise.
(k) Set switches as tabulated for
Initial Settings
in
table 4-1.
5.3.3
TRANSMITTER TURN-ON:
Apply ac
power to the subject transmitter and verify the
indicator indications are normal as follows:
NOTE
The transmitter has duplicated exciter/RF power
amplifier stages ('A and 'B'). When any of the
following procedures are for the active stage ('A' or
'B') only, the reference designation for side 'A' will be
identified and the reference designation for side 'B'
will be in parenthesis.
The following modules have been duplicated:
REF REF
DES DES
DESCRIPTION
'A'
'B'
A2
A3 Modulator/Power
Amplifier
Module
A4
A5 Exciter
Module
A7
A8 Power
Supply
Module
