Elekta Neuromag NM21283A, Руководство пользователя

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7 Manual tuning
36 NM21283A-A
see the plateau. If you go down too much, the current vs. flux char-
acteristics goes via zero and turns over, see Fig. Figure 7.1(b). Be
sure to be on the right side.
• Adjust the offset voltage so that the current vs. flux characteristics is
approximately in the middle of the screen
• From the point where the plateau on the bottom appears, increase
the bias setting until it has completely disappeared, see curve
.
You may decrease the bias further by one or two units to ensure sta-
bility. The current vs. flux characteristics should look rather smooth
now.
• If the current vs. flux characteristics is not smooth, set the gate volt-
age to 150. If this does not remove irregularities, try increasing the
bias setting, even with the expense of loosing some modulation
depth.
4. Adjust the gate voltage.
Figure 7.1 Bias tuning
Φ
a
I
B
Φ
a
I
B
(a)
(b)
V
B3
V
B2
V
B1
V
B2