GENERAL DESCRIPTION The FT-901DM is a precision engineered, high-performance I IF transceiver of advanced design, providing all band coverage (160 - 10 meters) on all modes of operation: LSB, USB, CW, FSK, AM, and FM. This transceiver operates at an input power of 180 watts SSB/CW and 80 watts on AM, FM, and FSK. Advanced features include PLL (Phase Locked Loop) frequency derivation, digital plus analog frequency readout with large display LED digits, a built-in Curtis 8043 1C electronic keyer, and memory frequency control circuitry. State-of-the-art receiver performance features include rejection tuning, dual-filter variable IF bandwidth tuning, and, for CW, an audio peak filter (APF) for unsurpassed rejection of unwanted signals. Other built-in features include VOX, semi-break-in CW with sidctone, 25 kHz calibrator, advanced noise blanker, RF speech processor, and a 20 dB RF attenuator for protection against receiver overload. All circuits, except the transmitter driver and final amplifier stages, are solid state, utilizing modern plug-in printed circuit boards, thus permitting easy maintenance. The FT-901 DM transceiver is entirely self-con-tained, requiring only an antenna and power source for operation. For base station operation, AC power voltages of 100/1 10/1 1 7/200/220/234 VAC may be chosen, though the unit normally is supplied with 1 17 volt capability. A DC-DC converter unit provides for mobile or portable operation. Selection of AC or DC power source is automatically made when the proper line cord is inserted. For mobile operation a separate switch is provided on the front panel to turn off the tube heaters while in the receive mode. With the heaters off, current consumption is only 1.1 amp. Among the available options on economy models FT901D/SD/DE are the memory unit, the keyer unit, the DC-DC converter, the FM unit, and the cooling fan. Optional equipment on all models are the 600 Hz CW filter and the 6 kHz AM filter. The entire FT-901DM transceiver weighs approximately 18 kg., and is 342 mm wide, 154 mm high, and 324 mm deep. A diecast front panel and heavy-duty case provide maximum protection against damage from shock and vibration during travel use. A BRIEF HISTORY OF THE FT-901 SERIES The FT-901 transceiver first appeared in the USA early in 1978 and immediately established a position of pre-eminence among “top-of-the-line” transceivers on the market. The FT-901 series has brought a number of never-before-possible technical features to the amateur community, along with traditional Yaesu quality design and purity of emissions. The receiver section, in particular, has impressive credentials. A dual-filter variable IF bandwidth control allows continuous variation of the IF passband, from 2.4 kHz down to 300 Hz. Also included is a rejection tuning control, for nulling out of any interfering signal within the remaining IF passband. For CW, and audio peak filter (APF) provides a significant reduction in background noise, in addition to razor-sharp selectivity. The receiver dynamic range — typically well in excess of 85 dB in CW bandwidth — is the best ever achieved in a production-line amateur solid-state receiver. The transmit side includes RF negative feedback for purity of emissions. A Curtis 8043 IC keyer is built-in on the FT-901 DM/DE models, providing high reliability and immunity to RF interference. Another innovation is the 10-second TUNE button, which activates the transmitter for 10 seconds for tuning purposes, then returns the rig to receive, thus saving the final tubes from excessive key-down time. The most exciting feature of the FT-901 series is the memory system, which provides for storage and recall of any frequency for control on transmit, receive, or transceive. This one feature largely eliminates the need for an external VFO in the traditional sense. That the FV-901DM synthesized scanning external VFO is hardly traditional bears this point out. With coverage on all modes (SSB, CW, AM, FSK.. and FM) on all bands from 160 through 10 meters, the FT-901 series is destined to maintain its position of dominance among top transceivers on the market. With some 2800 components assembled in one box, for a finite price tag, the FT-901 offers more performance per dollar than any other piece or collection of equipment on the market.