Yaesu FT-7900R Operating Manual

Also see for FT-7900R: Technical supplement

11FT-7900R OPERATING MANUALBASE STATION INSTALLATIONI NSTALLATIONNote that 9600 bps packet transmit-deviation adjustment is very critical to successful opera-tion, and can only be accomplished using a calibrated deviation meter (such as that found onan FM Service Monitor used in a communications service center). In most cases, the PacketData Input level (set via a potentiometer inside the TNC) must be adjusted to provide adeviation of ±2.75 kHz (±0.25 kHz). Check with your packet node’s sysop if you have anyquestions about the appropriate deviation level for your network. Note also that high through-put on 9600 bps frequently requires strong signals, so you may wish to consider the use of adirectional antenna such as a Yagi for communication with high-speed packet nodes.The setting of the 1200 bps Packet Data Input level is much less critical than it is at 9600 bps,and satisfactory adjustment to the optimum (±2.5 ~ ±3.5 kHz) deviation can usually be done“by ear” by adjusting the TNC’s 1200 bps TX Audio Level potentiometer so that the outgoingpackets (as monitored on a separate VHF or UHF receiver) are approximately the same levelas (A) the DTMF tones or (B) the 1750 Hz Burst tone produced using the microphone.Finally, note that the Menu (“Set”) mode allows you to set the Packet data rate (1200 or9600 bps) independently for each band. If you have trouble getting your FT-7900R torespond correctly during packet operation, check to be certain that you do not have Menu#26 (PKT.SPDPKT.SPDPKT.SPDPKT.SPDPKT.SPD) set to the wrong data rate.You may activate the microphone input while operating on the packet mode via the Menu#25 (PKT.MICPKT.MICPKT.MICPKT.MICPKT.MIC), if desired. Generally, we do not recommend this, as a “live” microphone’saudio input will tend to reduce throughput by interfering with the packets being transmittedby your radio.9600 BPS P ACKET SETUP1200 BPS PACKET SETUPDATAOUTDATAIN PTTPKSGNDDATA INDATA OUT(1200bps)DATAOUTDATAIN PTTPKSGNDDATA INDATA OUT(9600bps)