1) The keystone of F2 has gone to the upper side of bi-stable during the venting.
2) Opened the cross tube.
3) Pulled down the filters from the cross tube, but the keystone of F2 (only) did not move.
4) The height of BF was 84mm. The gap of vertical primary coils for the BF damper was about 1mm.
5) Opened the top chamber.
6) Set the height of F0 keystone from 5.5mm to 9.5mm by the additional weight.
7) Closed the cross tube and the top chamber.
I measured the transfer function of the GAS filter for check of F2 filter.
And I uploaded these graph.
according to these graph, ~2.3Hz peak was disappear. (previous data : 5244)
However I can not dicide what the F2 filter state is good or bad.
Miyamoto-kun,
As I mentioned in the e-mail, now the F2 GAS keystone seems to be fixed mechanically.
The key feature is the peaks in 0.7-1.3 Hz appeared in the transfer function of F3 GAS.
I attach the F3 GAS transfer function calculated with SUMCON, changing the state of fixing GAS.
In a healthy state (labeled as "Default"), two resonant peaks with comparable heights appear at 0.7 Hz and 0.95 Hz.
On the other hand, when the F2 GAS is fixed, a large peak at ~ 0.8 Hz is signifinant relatively to the following small structure.
The current situation of the F3 GAS transfer function seems to be close to the case of fixed F2 GAS.
Another evidence is the healthy transfer function taken in the ETMX tower test. >>> JGW-G1807671
There is a clear difference in appearance of the peaks in 0.7-1.0 Hz between the current result and the old data of F3 GAS.
Now the number of peaks are decreased and therefore I infer that the F2 GAS is not in an oscillatory state.
