7280 with noise

From: Nanjing China
email: macf@nari-relays.com
Model: 7280
Date: 25 Jul 2005

Comments

Hi,I have a lock-in amplifier of your 7280model.Now I have PD whose bandwidth is 700kHz, NEP is 3.8pW per squre root of Hertz, Transimpedance Gain is 150000 voltage per ampere, responsivity is 0.85 ampere per watt, noise(rms) is 0.4 mV. After a beam of light from a SLD(1310nm center wavelength and the FWHM is about 90nm) is modulated by one signal of 58 kilohertz(from a signal generator) it is input to the PD, and then the output of the PD is connected to the A input BNC connector by a coax cable of 50 ohm. And the other cable from the same signal generator is connected to the reference BNC connector. When we choose fast mode and set the time constant to be 1ms, the sensitivity to be 1mV, the even if the light is powed off the number of the 7280 is 0.008 mV, is this the noise of the PD?Please tell me how to set the parameter such as the time constant, the sensitivity, the DR, the reference phase, the AC gain ,and fast/normal mode of the 7280.