40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  ATF eLog  Not logged in ELOG logo
Message ID: 1366     Entry time: Wed Mar 30 20:30:45 2011
Author: Zach 
Type: Electronics 
Category: GYRO 
Subject: TRANS PD tuned and REFL PDs retuned 

 [Alastair, Zach]

Alastair finished building our first TRANS PD (S/N 03), and we tuned it and took a transfer function with the Jenne Laser:


Not sure quite what's happening up at 277 MHz. The gain at the readout frequency (100 MHz) is a bit higher than what is predicted by the model, but that's probably because Alastair used 200 pF as the diode capacitance, whereas it's closer to 100 pF with the 5V bias. 200 pF puts the diode pole (RC = ~10 ohm * 200 pF) at ~80 MHz, but it's probably more like 160 MHz, explaining the extra gain.

We also retuned the REFL PDs to have their readout and 2f rejection frequencies at 19 & 38 MHz, respectively. They match up quite nicely, save for some difference in the diode capacitance:


I still need to re-tune the EOM resonant circuit, which I will have to sneak in during a break in Frank's diode demolition derby tomorrow. Otherwise, we're ready to get the gyro gyroing again.

ELOG V3.1.3-