The receiver of this particular unit has active PIN diode switches instead of
passive switching diodes. These are used to protect the preamp and to gate the
decoupler and transmitter channels. The problem is the drive signal to turn on off
the PIN diodes is not there. The only schematics and details I have available are for
a previous revision and shows the common garden variety passive
diodes and low speed relay signal routing.
This signal is controlled by some long forgotten config file setting that
assigns the logic to turn on the high current PIN drivers in sync with the RF.
Does anyone out there know how this digital switch is set or what the file it is in?
Regards Scott
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A.Scott Chesnick
Design Engineer
US National Institutes of Health
In Vivo Center for Nuclear Magnetic Resonance Imaging
NHLBI/LCE Bld 10 Room B1d-161
9000 Rockville Pike
Bethesda, Md 20892