Thank you for purchasing the MFJ-1273B (MFJ-1273BM) Sound Card Radio Interface. The MFJ-1273B was designed for use in all sound card to radio applications.

This interface is for those who operate mostly digital modes and do not need a microphone input. Great care was taken to make sure hum, noise, and distortion are minimized or eliminated, insuring the best possible signal from your equipment.

Before attempting to use the MFJ-1273B, please read section 2.0. This section contains important
information about interfacing the MFJ-1273B with your transceiver.

We will start with a brief introduction into the special features that make your Sound Card Radio Interface an important addition to Amateur station with a computer.

MFJ-1273B Features:

• Serial Port: This port allows the computer to control the push-to-talk of your radio.
• Microphone/Radio plug-in jumpers: Internal jumpers program microphone wiring for any brand or model of radio with the appropriate 8-pin connector. There is no need to solder tiny plugs and wires or purchase adapters.
• RFI Proof Circuitry: RF suppression and line isolation virtually eliminates RF feedback, hum, and distortion. An isolation transformer prevents audio ground loops.
• Level control: A receiver-to-sound card drive level control is supplied. No need to adjust sound card level settings every time you change modes.
• Power supply: No external power is needed.
• Rugged Construction: A solid all aluminum cabinet and sturdy construction gives the MFJ-1273Bm mechanical and electrical durability.
• Also included: CD, RS-232 cable, audio cables and microphone cable.