CES SUPPORT 407-679-9440
Page 10
MAN79 © CES 2009
Following are instructions for each connection and adjustment that is required by the RM-20 for proper pperation.
Installation procedure will be outlined first followed by the adjustment procedures. All connections to the radio (s)
are made via the rear panel DB-15 connector, and should be performed by a qualified two-way radio or
communications engineer. Ensure that static precautions are observed and that power is not applied during
installation. Shielded audio cable should be used for all audio signal line connections to transmitter-receiver
combination. Terminate ground shields at DB-15 connector only to prevent hum and noise due to ground loops. The
shield at the other end of the cable must be left unconnected. Place the unit as close as possible to the transmitter-
receiver combination, thus allowing the shielded cables and wires to be as short as possible. Once the installation
has been successfully completed, continue with the adjustment section of the manual.
Do not program the RM-20
until all the installation and adjustments have been successfully completed.
2.10 Radio and Auxiliary relay interface. J3- DB-15
Pin 1- PTT-NO
Connect to the Push to Talk of the transmitter. This is normally connected at the microphone PTT input.
*** See Pin 9 (PTT Common)***
Pin 2- PTT-NC
This connection is generally not used. In applications where two RM-
20’s are used for cross-band applications, this
contact may be used.
See Figure 3.0
Pin 3- Aux. Common
(optional)
Pin 4- TX Disable
This is an input that (when active) disables the RM-20s repeat and decode functions. This connection is typically
used if two RM20 are used in a cross-band application. The active state of this input is programmable.
Pin 5- CTCSS TX
If CTCSS is to be used on the repeater system, this connection must be made to a suitable tone injection point in the
transmitter. Consult the manual and/or schematic of your transmitter for this connection. The radios microphone
audio input
cannot
be used for this connection.
Pin 6- TX Audio
This connection is normally made to the transmitter microphone high input.
Pin 7- RX Audio
Some consideration must be given to this input. The RM-20 must have a way to determine when there is activity on
the receiver. If this input is connected to the IF detector (discriminator) output of the receiver, the RM-20s internal
squelch circuit will provide the carrier detection. If a filtered or squelched audio source is used, then the internal
squelch circuit will not function properly and an additional connection (External COR) will be required.
Also, if it is intended for the RM-20 to decode CTCSS (Sub Audible Tone), then this input must be connected to the
discriminator.
Pin 8- Ground
Connect this pin to the common ground on the radio. If external power supply is used, tie all the grounds together.
