NAOJ GW Elog Logbook 3.2
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EleonoraCapocasa - 11:18, Tuesday 26 March 2019 (1258)
15 MHz TAMA PD modification
[Matteo, Eleonora C.]
In order to have a larger error signal for the CC in reflection from OPO we have modified the15 MHz resonant TAMA PD (S/N00Z405) to increase the gain of the RF channel.
We have modifiided the RF amplication stage as follow (pic 1 and 2):
R1 = 1K (before it was disconnected)
R2 = 9.1K (before it was shortcutted)
The gain has changed from 1 to 10.
The TF of the PD measured before and after modification are shown in pic 3.
The TF was measured by injecting the signal directly on PD pin (A), so they don't match those reported in (http://tamago.mtk.nao.ac.jp/tama/ifo/general_lib/circuits/011217_PD/011217_PD_fit.pdf) but they are just a relative measurements.
Images attached to this report
