From: David Cussans [David.Cussans@bristol.ac.uk]
Sent: 05 November 2008 10:42
To: Dave Cockerill
Subject: Frequency response of EE HV filter boards

Attachments: hv_filter_model_signal_output.pdf;
hv_filter_model_anode_dynode_signal_output.pdf; hv_filter_model.pdf


Dave,

    I have attached plots shows the simulated frequency response of the EE HV filter boards.

    In hv_filter_model_signal_output.pdf a signal is applied to the VPT anode and the response at the signal coax is shown.
    No surprises - it is a high-pass filter. The -40dB at high frequency is due to the way I represent the pre-amp as a 1-ohm resistor.
    In hv_filter_model_anode_dynode_signal.pdf signals are applied to both the anode and dynode HV supply lines and the response at the anode , dynode VPT connections and the signal coax are shown. The route between the supply lines and the anode and dynode connections are (RC)^2 and  RC  low-pass filters. The route to the signal output is a (RC)^2 low-pass followed by a RC high-pass. Remember to subtract the -40dB from the signal response to see the sensitivity to noise injected on the supply lines compared to signal injected into the anode.

    The software, simulation and test-data are available under https://svn.phy.bris.ac.uk/svn/uob-hep-pc019a/trunk/ ( user/password = anonymous/anonymous )

    I went over to Bat 27 yesterday afternoon and started to back-up the test-data. I have taken the USB 'scope and tucked it away safe in the Bristol office. It is only a 2MHz 'scope costing CHF250, but it is fine for debugging the test-stand. One of Peter's HV supplies is connected to the HV soak-test stand. I think the other (a spare) is still in the crystal palace. We should get both them together. I can't get into the crystal palace. Are you available about 4pm today to go and have a look in the XTal palace for Peter's HV supply?

          Cheers,
                David


Ps. Is there any way of looking at the status of the EE HV whilst on shift? There is a block of EE+02 that isn't responding to laser pulses and doesn't seem to be responding to cosmics either.