Theory, Design and Tests on a Prototype Module of a Compact ...

6. THE FINAL STEPS OF THE TUNING PROCEDURE 89
tank # cell type left [mm] right [mm]
1 AC +3.5 +7.9
CC +0.3 +7.0
2 AC +6.7 +6.2
CC +0.3 +7.0
3 AC +5.0 +6.2
CC +0.3 +7.0
4 AC out +4.4
CC +0.3 +7.0
Table 5.2. tuners positions for the bead pulling of figure
5.18.
Figure 5.19. The first good bead pulling result.
The figure 5.18 shows the bead pulling measurement after some
interventions on the tuners resumed in the table 5.2. The π/2 frequency
was 2996.96 MHz <strong>and</strong> SBB = +222 kHz.
6. The final steps of the tuning procedure
It is clear from the previous section that the tuning procedure
should be made by little steps in order to be sure to keep positive
the two stop-b<strong>and</strong>s <strong>and</strong> to fully underst<strong>and</strong> the results on the field
level. Unfortunately, sometimes the intervention on one tank has also
effect on the near tanks <strong>and</strong> this implies that all the interventions must
be careful made <strong>and</strong> without big displacements of the tuners.
The figure 5.19 shows a bead pulling measurement 14 that was quite
good since the field level was flat within ±5%. The π/2 frequency was
14 Note that the figure 5.19 is the output plot of the network analyzer. The
scale is the same of the previous figures, the maximum being 8 divisions.