The MFJ-434B Contest Voice Keyer is a microprocessor-controlled device that allows you to send your call sign, contest exchanges, or any other messages in your natural voice. It can record and play up to five pre-recorded messages, with a total duration of 75 seconds. The keyer utilizes the latest EEPROM technology, which ensures that your messages are stored for up to 100 years without the need for battery backup. It can be connected to virtually any make of rig, and the 8-pin mic socket can be customized using internal jumpers. All lines are RF-filtered to eliminate RFI, feedback, and distortion. Additionally, the keyer features an isolation transformer that eliminates hum and distortion caused by ground loops. It is suitable for use with Kenwood, Icom, Yaesu, and Alinco rigs, and comes with a built-in speaker amplifier. The power source can be either a 9V PP3 internal battery or a 9-15V DC external power supply (not included). The dimensions of the keyer are 165 x 65 x 165mm.