Belfort AWOS, Maintenance Manual

Page: 84 / 95

BELFORT
INSTRUMENT
Proprietary Information
18)
Enter the command “B” space, “3” space, “1” space and return to tell the DCP to
select RF frequency 467.925 MHZ at 1W.
19)
Enter a “K” command to start the DCP to transmitting a 1 Khz tone.
20) On the HP8920D, note the TX Frequency value and record it on the
Commissioning / Annual Record Data Sheet as the DCP FCC Authorized
Frequency value. Frequency will be 467.925 MHZ +-2 K hz. If the Frequency is
out of range, then the Ritron RF Transceiver should be replaced.
21) On the HP8920D, note the TX Frequency Deviation value and record it on the
Commissioning / Annual Record Data Sheet as the DCP Frequency Deviation
value. Frequency Deviation should be 2.2 Khz +- .5 Khz. If the Frequency
Deviation is out of range, then the Ritron RF Transceiver should be replaced.
22) On the HP8920D, note the measured RF power value. The RF power should be
between .75 and 1w. If the value is in range, then record the value on the
Commissioning / Annual Record Data Sheet. If the RF power is out of range,
then the Ritron RF Transceiver should be replaced.
23) On the HP8920D, note the measured RF modulation value. The modulation value
should be between 78 and 85 %. If the RF modulation is in range, then record the
value on the Commissioning / Annual Record Data Sheet. If the RF modulation
is out of range, then the Ritron RF Transceiver should be replaced.
24)
Press any key on the PC keyboard to stop the “K” 1 Khz tone output.
25) Disconnect the HP8920D from the 50 ohm coax cable. Connect the coax cable to
the Input connector of the Bird Model 5010 Directional Power Sensor. Connect
the coax cable from the antenna to the Output connector on the Bird Model 5010.
Connect the Bird Model 5010 Interface cable to the Bird Model 5000-EX. Power
on the Bird Power Meter.
26) On the Bird Power Meter panel, select VSWR measurement.
27)
On the PC, enter a “K” command to start the DCP to transmitting a 1 Khz tone.
28) On the Bird Power Meter, note the measured VSWR value. The VSWR should
be <3.0:1. The optimal value is 1.0:1. If the VSWR is in range, then record the
value on the Commissioning / Annual Record Data Sheet. If the VSWR is out of
range, then the antenna cable should be inspected for damage or kinks, or the
Ritron RF Transceiver should be replaced.
29)
Press any key on the PC keyboard to stop the “K” 1 Khz tone output.
30) Disconnect the Bird Model 5010 Directional Power Sensor from the antenna and
DCP coax cables. Reconnect the DCP antenna cable back to the Ritron
Transceiver. Replace the cover on the DCP enclosure.