The RSA-M3 is used to provide a simple and inexpensive method of connecting voice logging recorders to two-way radios that are not remote controlled (with remote controlled radios most digital logging recorders can be directly connected to the control pair). It combines receive and transmit audio at levels matched to the line input of voice logging recorders. It also provides transformer isolation and RF bypass.


For use only with two-way radios that have switched transmit audio (about 300 mv of transmit audio that is muted by the radio when not transmitting). Many radios no longer mute the transmit when not transmitting. If your radio does not mute the transmit audio when not transmitting, see: Omnicron RSA-M4 or RSA-U5 adapters.



The RSA-M3 is supplied with cables and connectors which have been wired to meet most standard applications. It can also be customized to meet unusual requirements. Consult your place of purchase if cables are required with non-standard lengths, connections, or circuitry.


1. The short three wire gray cable connects to the two-way radio audio.


a) Connect the BLACK lead to radio common (chassis ground).


b) Connect the GREEN lead to receive audio (about 0.5 vAC when active).


c) Connect the RED lead to transmit audio (about 0.1 vAC when active).


2. The RJ-11 telephone style jack on the RSA-M3 connects to your recorder’s audio input. Receive and transmit audio are mixed together on the center two pins of this RJ-11 jack. Use the eighteen-foot phone cable supplied with each RSA-M3 or other suitable wiring to connect from this jack to your recorder.