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MDS 4710/9710 I/O Guide
MDS 05-3305A01, Rev. B
7.2 Helical Filter Adjustment
If the frequency of the radio is changed more than 5 MHz, the helical
filters should be adjusted for maximum received signal strength (RSSI).
To adjust the filters, proceed as follows:
1. Remove the top cover from the transceiver by loosening the four
screws and lifting straight up.
2. Locate the helical filters on the PC board. See Figure 13.
3. Apply a steady signal to the radio at the programmed receive fre-
quency (–80 dBm level recommended; no stronger than –60 dBm).
This can be done with a signal generator or an over-the-air signal.
4. Measure the radio’s RSSI using one of the following methods:
• With an HHT (See Section 5.0, TRANSCEIVER PROGRAM-
MING on page 17).
• With MDS Radio Configuration Software (See Section 7.4,
Upgrading the Radio’s Software on page 38).
• With a voltmeter connected to Pin 21 of the
DATA INTERFACE
connector (See Section 4.2, RSSI Measurement on page 16).
5. With a non-metallic adjustment tool, adjust each section of the
helical filters for maximum RSSI. Re-install the cover to the trans-
ceiver.
Invisible place holder
Figure 13. Helical Filter Locations
FRONT PANEL
OF RADIO
J301
U104
U101
U202
HELICAL
ADJUSTMENTS
U203
SHIELD
COVER
