Sunday, June 22, 2008

Oldie but a Goodie: Yaseau FT-901DM Competition Grade Transceiver.

You may be asking why the hell would I still want and still keep (and use!) a 30-year old, bulky, heavy ‘boat anchor’ transceiver? For collecting, good performance? At the time of it's release it was the top of the line for Yaesu and was competition grade. Performance wise, many years down the line it is still ranked no. 15 currently as far as close in dynamic range for high performance transceivers is concerned and is still quite hard to beat. In fact many of the so called top of the range HF transceivers now do not have a RF front end that is so hot to trot and cannot even touch the Yaesu FT-901DM. That is the real reason - performance. Yes this amazing old vintage radio has a receiver can perform or out perform better the the expensive models of today! Matched with the FTV-901R transverter and I have a high performance VHF/UHF operating system.

The year was 1977, the FT-901DM was built and designed following on the success of the FT-101 line, the FT-901DM was crafted as a “hybrid” transceiver, using all solid state design except for the driver and final amplifier stages. It uses plug-in circuit boards, popular in the 101, 225, 625 and 301 lines, and it featured a die-cast front panel and spectacular solid mechanical construction inside the case. The FT-901 was among the “cleanest” internal structures that Yaesu ever created.

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.

Don't take my word for it, take a close look at the receiver tests, done by Bob Sherwood of Sherwood Engineering (link). Even after 30 years, the FT-901 is still ranking #15 - defeating numerous modern transceivers with ease. Bob is a respected RF Engineer and what he says about receiver design performance and rankings is basically accepted as Gospel by DXers the world over and is not disputed.

On the transmitter side, the 901 uses a pair of 6146B tubes in the finals, and utilized RF negative feedback to ensure low IMD products. The 901 series was always renowned for its outstanding audio quality and signal purity. Now do you want receiver performance or bells and whistles?

Finally, the FT-901DM included a built-in Curtis Model 8043 Electronic Keyer. The Curtis IC was the “prestige” keyer of the day, and it eliminated yet another box from the desk of an owner.

FT-901 Web pages:

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