RADIOBEACON TRANSMITTER
ND500II (125 WATTS) DOUBLE SIDEBAND - NO VOICE
Page 5-2
15 September 2003
(a)
A precision, resistive, 50-ohm dummy load that
is rated at a minimum of 250 watts and has
provision to accurately display the RF power
being applied to it.
(b)
A digital multimeter with appropriate test leads.
(c)
A frequency counter, for audio and carrier
frequency measurements, with suitable test
probes (BNC coaxial connector terminated and
with clip-on probes).
(d)
An oscilloscope, with suitable test probes
(BNC coaxial connector terminated and with
clip-on probes).
(e)
A stopwatch to measure the keyer frame lengths
to an accuracy of ±1.0 seconds.
(f)
A variac that can be adjusted ten percent either
side of the nominal AC power source voltage.
(g)
A spectrum analyzer complete with a notch
filter to attenuate its input signal level at the
assigned carrier frequency.
(h)
A distortion analyzer to measure audio
distortion.
(i)
A variable, 0 to 30V, 1A, DC power supply.
(j)
A variable, 0 to 50V, 20A, DC power supply.
5.3.2
FUNCTIONAL TESTS/
CALIBRATION PREREQUISITES
: The
following prerequisites must be completed prior to
performing any functional test and/or calibration
procedure:
5.3.2.1
Pre-installation Considerations
: Verify
the user determined options, that are selected during
initial installation, have been selected and the
necessary wiring has been connected/installed, as
follows:
(a)
Verify the pre-installation requirements for the
RF synthesizer PWB A9 have been completed,
as mentioned in paragraph 3.8.4 and detailed in
the RF synthesizer PWB’s service instruction
manual.
(b)
Verify the pre-installation requirements for
keyer PWB A3 have been completed, as
detailed in paragraph 3.8.5.
(c)
Verify the appropriate primary and secondary
winding taps of power transformer A1T1 have
been selected and connected as detailed in
paragraphs 3.8.3 through 3.8.3.2.
(d)
Verify the pre-installation requirements for
harmonic filter assembly A7 have been
completed, as detailed in paragraph 3.8.6.
(e)
Verify the pre-installation requirements for low
voltage power supply on/off PWB A1A1 have
been completed, as detailed in paragraph 3.8.7.
(f)
Verify the pre-installation requirements for
remote interface PWB A11 have been
completed, as detailed in paragraph 3.8.8.
(g)
Gain access to the adjustments on the PWBs by
removing the top cover from the transmitter.
5.3.2.2.
Transmitter Turn-On
: Apply main power
source to the transmitter and verify the indicator
indications are normal, as follows:
(a)
Set switches as tabulated for
Initial Setting
in
table 4-1.
(b)
Verify the requirements of paragraph 5.3.2.1
have been completed.
(c)
Set
MOD %
potentiometer A4R2, on modulator
driver PWB, fully counter clockwise.
(d)
Set
O/P PWR
potentiometer A4R31, on
modulator driver PWB, fully counter
clockwise.
(e)
Disconnect RF drive from power amplifier/
modulator A6 by disconnecting connector P11
from its mating connector (A6J2).
(f)
Disconnect mod drive from power amplifier/
modulator A6 by disconnecting connector P10
from its mating connector (A6J1).
