The Yaesu FT-8900R quad-band ham radio outputs 50 watts on the 29/50/144MHz Amateur bands, and 35 watts on the 430MHz band. Cross-band repeat, dual receive and numerous memory channels are all included. Features include a remote-head mounting system in which you can separate the head from the body to ease mounting in compact vehicles. Problems with the 8900 can be related to the installation and operation including connections, power levels and controls.
Provide adequate ventilation around the body unit if the radio becomes excessively hot, or cuts out. Some long transmissions at 50 watts will create significant heat. Move the body away from heater ducts and other aftermarket electronics like an amplifier that also creates heat. Don't place shopping bags, clothing or other objects on the radio body. Avoid using the radio in environments where the ambient temperature reaches 60 degrees C. or more.
Use high-quality coaxial cable between the Yaesu FT-8900 and the antenna if transmission quality is poor. Remember that a 25-foot-long cable with .50dB of loss at 29MHz will have 6dB or more of loss at 446MHz.
Connect the supplied power cable directly to the vehicle's battery to avoid voltage drops that can cause transmission problems. The included cable has a 15 amp fast-blow fuse fitted in-line, so you don't need to worry about surges. Red should connect to the positive and black to the negative on the battery. Use colour-coded No. 12 AWG wire if you need to extend the included cable.
Check the rear connections if you continue to have problems. The antenna should be tightly screwed onto the antenna jack, labelled "Antenna," external speakers plug into "Ext Sp" and the six-pin mini-DIN connector is an interface for a packet node controller labelled "Data."