ELCB
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8 ELCB
8.1 Introduction
The Extended Lock Control Board (ELCB) combines two former boards, the CPU and the
LCB. Therefore it provides two main functions - the Digital Lock (as it is described in the
Deadalus Lock Manual) and the control of the complete AV4 BSMS, (e. g. Shim, Lift,
Gradient Amplifier). The latter functions are described in the AV4 BSMS chassis and related
subunit chapters.
All former Lock functions have been adapted to the new hardware platform. The analog
design of the current source is basically the same as on the LCB, however some of the
former components have been replaced by modern ones. Therefore, the electrical
performance could be improved in parts.
Using the same algorithm for evaluation of the closed loop Lock regulation, the new ELCB is
fully compatible with the LCB. It has the same or a better performance for NMR experiments.
Since the new DSP has a much higher performance, it provides faster handling of real time
Lock Hold pulses, which now may range down to a length of 100 microseconds.
Additionally, it was possible to implement a more sophisticated method for locking in, which is
now very reliable. While the Lock is sweeping, the „wiggles“ of the Lock signal are now
analyzed. This provides a simple and fast lock in. The Auto-Lock functions have been
optimized as well.
8.2 Lock Parameters and Technical Data
Parameter Min Factory
Default
Max Unit Notes
Lock Field (H0) -9999
-170
+5000 +9999
+170
Field Units
mA
Lock Regulator -99
-1.70
0 +99
+1.70
Field Units
mA
Sweep Amplitude 0 100
4000
68.0
100
4000
68.0
Sweep Units
Field Units
mA
Sweep Rate 0.01 2.00 5.00 Hz
Lock Phase 0.0 180.0 359.9 Degrees 1)
Lock Power -50.0
-60.0
-60.0
0.0
0.0
0.0
+10.0
+0.0
+10.0
dB
dB
dB
2)
Lock RF Gain 2H
Lock RF Gain 19F
75.0
55.0
120.0
120.0
155.0
135.0
dB
dB
Lock Shift -200.0 0.0 200.0 ppm
Lock Drift -2000.0 0 2000.0 Field Units/24
hours
3)
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