Model 5O0 is the standard Transmaster. Model 600 incorporates TVI Elimination. Models 500S & 600S have in addition a built-in "Clamp" tube Modulator plus a switching arrangement whereby the Power Amplifier may be turned off to tune-up or zero-beat another signal without blocking the receiver or causing unnecessary interference to other stations on the frequency. This switch also provides a means for switching from phone to C. W. operation. All units are designed to operate on 160, 80, 40, 20, 15, and 10 meter bands. Crystal or VF0 operation is feasable on all bands. Installation of these units is extremely simple, requiring only an antenna, key and 115 volts 60 cycles for all Models, plus & high impedance microphone for Models 500S & 600S. The Power Amplifier operates straight through on all bands.