750/375 and 40  khz  combs in 327 receiver.

16apr06

18apr06: comb is coming from the sband console in dome.
16apr06: comb appears


16apr06 Initial report of comb.

plots:
750 Khz comb (.gif)
an average spectra of 40 seconds (.ps)  (.pdf)
 39 Khz comb (.gif):
an average spectra of 40 seconds (.ps)  (.pdf) :
 

    Two combs were seen in the 327 receiver in data taken on 13apr06. One comb is at 750 Khz while the second comb is at 39.45 Khz

The 750 Khz comb:

The first image shows the 750 Khz comb (.gif): The strength of the birdie is seen in an average spectra of 40 seconds (.ps)  (.pdf) :

The 39.45 Khz comb

    The image shows the 39 Khz comb (.gif):     The strength of the birdie is seen in an average spectra of 40 seconds (.ps)  (.pdf) :

When did the combs appear?:

    The 750 Khz comb:


    The 39 Khz comb:
    It was seen on 13apr06 in the high resolution data. The x111 data does not have high enough resolution to see this comb.

Summary:

processing:x101/060413/327_combs.pro


18apr06 comb is coming from the sband console in dome  (top)

    Data was taken on 18apr06 to see if the 750 kHz and 39 kHz comb were coming from the sband console in the dome. We used the 327 receiver. The setup was:     The first image shows the dynamic spectra for the 25 Mhz band (.gif) :     The second image has the dynamic spectra for the 390 Khz band (.gif):     Average spectra were made during the door open, door closed, and power off times: The plots show the strength of the combs (.ps) (.pdf):     After inspecting the inside of the sband cabinet, we found that some of the internal metal covers had not been screwed into place (there were lots of screws).  After securing these covers we took some more data.
    The dynamic spectra show the 25 Mhz band after the internal covers were secured (.gif):

Conclusion:

processing: x101/060418/chksbcab.pro



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