The real “breakthrough” feature of the Yaesu FT-901DM was the memory system. In a day when the only concept of “memory” was a quartz crystal, the FT -901DM allowed the operator to push a button, wait about five seconds, and in that time the synthesizer would lock in on the current operating frequency and store it for later recall. No other HF radio in the Ham world had memory, and it was a huge performance breakthrough that set the stage for the memory-based transceivers of today.
Another area where the Yaesu FT-901DM shone was in its much improved receiver performance. The FT-901DM was the result of a major effort by Yaesu’s top receiver design engineers, who included a permeability-tuned RF preselector (similar in concept to the “µ-Tuning” modules in today’s FTdx9000! Now may be you will sit up and take note), and the entire receiver section featured at least 10 dB more dynamic range than any previous solid-state receiver from Yaesu. At the time, the dynamic range of the FT-901DM was, by far, the best in the industry, and it led to the wide acceptance of this model in DX and contest circles. Indeed the close in dynamic range is topped today by only a few other very special class top of the range HF transceivers but at much higher prices! So if you can find a FT-901DM or a Ft-902 in good overall condition, it is worth buying one as a second rig. The differnce between the 901 and 902 is purely one of bands, the 902 has the WARC bands included, everything elese is the same.
FT-901 Web pages: