Specifications

MDS 05-3438A01, Rev. E MDS 4790/9790 Series I/O Guide 19

Invisible place holder

Figure 15. Antenna Connection with External Duplexer

Application #3—

External Cavity Filter

In some areas, interference from strong signals such as paging transmit-

ters, may require the use of a cavity filter. A cavity filter is an exter-

nally-mounted device that is tuned to the frequency of an interfering

signal. It removes or greatly attenuates the unwanted signal before it is

detected by the master station receiver. Contact the factory for filter

ordering information.

Because the cavity filter must be installed inline, between the master sta-

tion receiver and the station antenna, the cabling arrangement in

Figure 16 is required.

Invisible place holder

Figure 16. Antenna Connection with External Cavity Filter

Application #4—

External Duplexer

and/or Cavity Filter

on units shipped

prior to June 1, 2000.

On units shipped prior to June 1, 2000, a maximum of two coaxial con-

nectors are included on the rear panel. If only one connector is present,

it connects directly to the antenna as shown in Figure 14.

If the radio is equipped for use with an external duplexer, a second con-

nector will be included (Figure 17). In this case, the right connector acts

as the transmit output (to the duplexer), and the left connector acts as the

receive input (from the duplexer).

Figure 18 shows the required cable connections between the radio and

an external duplexer (and cavity filter, if required).

Master Station

Ext. Duplexer

RX TX

ANT

Master Station

Cavity Filter

IN OUT

ANT