The X-100D (ca. 1965-ca. 1967), the X-150D (ca. 1968-ca. 1969) and the X-165D (ca. 1971-1973)
The 100-series models are all single motor decks and they haven't been available with a built-in main amplifier.
They all use the Cross Field system for recording and they have 3 speeds. However, according to the 1969 magazine, the X-150D also has the ability to use a fourth 15 ips speed. The highest speed could be obtained by using a capstan speed change sleeve. These sets are very similar and they all have the same functions. I guess the difference could be found inside these decks.
The X-100D is the only one from this series with the rubber reel retainers. Other functions and switches: auto stop/shut off switch, 3 mode equalizer switch, 3 digit tape counter and seperated left and right line in level knobs.
These sets are almost identical. The X-201D has a few internal improvements and has been changed a bit externally. The X-200D has "solid state" written on the front and has germanium semi-conductors; the X-201D has silicon semi-conductors. The X-200D has shifting potmeters for line in, the X-201D has the more common round 'line in' level-knobs. The X-201D has larger VU-meters as well.
Since the X-201D has two reverse sensing poles, this deck can make an continuous reverse cycle. Both decks have three speeds (4,75 9,5 en 19,0 cm/s) and they have an auto shut-off function which is activated when the right tension arm falls down when the tape runs out.
When this happens after fast winding, the FF/REW knob will be turned into the 'stop' position mechanically. After playback or recording the pause knob will be lifted automatically. The equalization switch and speed switch are separated and thus independent. Both sets have one erasehead, one playback/rec head and one cross field head (bias head). When the deck goes into reverse mode, the playback head will be drawn back by a solenoid; a relay switches the head wires.
The X-200D and X-201D both have a wooden cover. A special set of adapters ( EA-10 ? ) has been available to mount 10.5" reels on these small sets.