Page 2 of 7 XR3/XR6 Frequency Change Procedure
Issue 1.0 IS07012
2 INSTRUCTIONS
The frequency change procedure
comprises four main steps:
• RF frequency change (see 2.1)
• Output filter tuning (see 2.2)
• RF power module tuning (see 2.3)
• Transmitter fine tuning/test (see 2.4)
WARNING
The XR3/XR6 transmitter uses a 312 V
dc power supply. Use extreme caution
when working near these lethal
voltages.
(a) Set the output power to 0 W, turn off
the transmitter and turn off the ac
power source.
2.1 RF Frequency Change
The RF synthesizer PWB(s), in each
XR3/XR6, contains frequency dependent
switches that select the carrier frequency
and jumpers that are used to configure the
PWB.
Use a small screwdriver to set binary
coded decimal (BCD) switches S1 through
S5 on each RF synthesizer PWB for the
desired carrier frequency when they are
read from left to right (S1 through S5).
(a) Set BCD switches S1 through S5 for
the new carrier frequency, noting each
switch represents a significant digit in
the carrier frequency (expressed in
kHz) as follows:
- S1 is thousands digit (x1000)
- S2 is hundreds digit (x100)
- S3 is tens digit (x10)
- S4 is units digit (x1)
- S5 is the tenths digit (x0.1)
See Figure 1 for switch location and
examples of switch settings for
specific frequencies. The arrow on the
segment selector of each switch
points to its numerical selection.
Figure 1: Switch Setting Examples
2.2 Output Filter Tuning
The next step is to change the output filter
components according to the new carrier
frequency.
NOTE
Some of the capacitors that are already
installed in the transmitter’s three
capacitor banks may be used at the new
carrier frequency. Nautel’s Customer
Service department will have checked the
installed capacitors against the capacitors
required for the new frequency and only
provided the capacitors that are not
already in the transmitter.
4
3
2
19
8
7
5
0
6 6
5
7
8
46
5
7
82
3
46
5
7
82
3
4
19
0
19
0
19
0
0
91
6
5
7
82
33
2
4
12 049
x1000 x100 x10 x1 x0.1
FREQUENCY (kHz)
S1 S2 S3 S4 S5
6
0
5
7
8
91
2
3
464
8
7
5
6
5
7
82
3
46
5
7
82
3
4
19
0
19
0
19
0
3
2
0
91
6
5
7
82
3
4
00056
x1000 x100 x10 x1 x0.1
FREQUENCY (kHz)
S1 S2 S3 S4 S5
1294 kHz
560 kHz
BCD switches
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