The typical modern transmitter has a pi-network tank circuit and will work into resistive loads of 50 to 75 ohms with Voltage Standing Wave Ratios (VSWR) of 2:1 or less* This resistive load can only be achieved with a resonant antenna; thus for multi-band operation multiple antennas are required. Space and cost considerations render this solution impractical for most amateurs- The MN-4 impedance-matching network can: 1. Measure feedline VSWR, then reduce the VSWR at the transmitter output to 1:1. 2. Monitor transmitter power output in watts directly and continuously. 3. Attenuate 2nd harmonic output from transmitter by 25 to 35 dB; thus it may eliminate the need for a low-pass TVI filter. 4. Match an antenna to a transmitter having fixed loading. 5* Give optimum match with multi-band antennas. 6. Precisely match transmitter to an antenna across a complete amateur band. 7. Permit "off the air" transmitter tuning and antenna matching at low power using dummy load. 8. Stores antenna loading adjustment for transmitter when switching from "barefoot" to linear amplifier operation3 as network is by-passed in DIRECT position of bandswitch. 9. Match transmitter output to linear amplifier which does not have 50 ohm input impedance. 10. Help localize trouble by comparing transmitter output into antenna and into dummy load.