Some time ago bought one on Ebay for under $50 just because it looked
interesting. It isn't a prototype but most of the FEI units probably
had limited production. It seemed to be more complicated than I
expected it to be but if I understood it better it would make more
The 10Mhz board is enabled/disabled by the int/external switch. The
10Mhz output and EFC from this oscillator board are connected to the
interface board. I believe that these 2 boards and the switch/connector
on the back allow you to use the internal 10Mhz oscillator to output
10Mhz and send 10Mhz on (perhaps a connector marked J4) to a comparator
board. If I recall this part of the unit should work independant of
the other boards.
The comparator board is probably a PLL that compares its 10Mhz input
with its 100Mhz input and outputs an EFC voltage to the 100Mhz
oscillator. the 100MHz oscillator output goes to the amplifier board
with two 100Mhz outputs on the back panel. There is also a 100Mhz
signal that goes back to the PLL board so the 100Mhz is locked to
the 10Mhz oscillator or an external input (if I remember correctly).
There are also other wires that control the light and other stuff
but I didn't trace them out and my unit seems to work as intended.
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