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Entry  Fri Sep 4 20:42:14 2015, gautam, rana, Update, CDS, Checkout of the Wenzel dividers TEK00000.PNGTEK00001.PNGTEK00002.PNG
    Reply  Tue Sep 29 03:14:04 2015, gautam, Update, CDS, Frequency divider box IMG_0014.JPGIMG_0015.JPG
       Reply  Fri Oct 9 19:54:58 2015, gautam, Update, CDS, Frequency divider box - installation in 1X2 rack IMG_0027.JPGtime_seris_25MHz.pdf
          Reply  Mon Oct 12 17:04:02 2015, gautam, Update, CDS, Frequency divider box - further tests calibration.pdfsystematics.pdf
             Reply  Wed Oct 14 17:40:50 2015, gautam, Update, CDS, Frequency divider box - further tests time_series_input_signals.pdfcalibration_20151012.pdfsystematics_20151012.pdf
                Reply  Tue Oct 20 17:36:01 2015, gautam, Update, CDS, Frequency counting with moving average 
                   Reply  Fri Oct 23 18:36:48 2015, gautam, Update, CDS, Frequency counting - workable setup prepared Yscan.pdf
                      Reply  Fri Oct 23 19:27:19 2015, Koji, Update, CDS, Frequency counting - workable setup prepared 
                         Reply  Sat Oct 24 12:34:43 2015, gautam, Update, CDS, Frequency counting - workable setup prepared Yscan.pdfFrequency_readout.pdf
                      Reply  Thu Nov 5 03:04:13 2015, gautam, Update, CDS, Frequency counting - systematics and further changes Systematic_error.pdfsystematics_origin.pdf
Message ID: 11647     Entry time: Tue Sep 29 03:14:04 2015     In reply to: 11579     Reply to this: 11683
Author: gautam 
Type: Update 
Category: CDS 
Subject: Frequency divider box 

Earlier today, the front panels for the 1U chassis I obtained to house the Wenzel dividers + RF amplifiers arrived, which meant that finally I had everything needed to complete the assembly. Pictures of the finished arrangement attached. 

Summary of the arrangement:

  • Two identical channels (RF amplifier + /64 divider + /256 divider), one for each arm
  • The front panels are anodized, and isolated SMA feedthroughs are used 
  • Given the large number of units to be supplied with DC power (2 amplifiers + 4 dividers), I chose to use two D1000217 power regulators (the default configuration takes +-18V as input, and outputs regulated +-15V, which was fine for the dividers, but the ZKL-1R5 requires +12V, so I changed the resistor R2 in the schematic from a 10.7K to 8.451K so as to accommodate this).
  • The amplifiers and dividers are mounted on a steel plate, which is itself mounted on the chassis via insulating posts. 

Testing:

  • I first verified the power regulator circuitry without hooking up the amplifiers/dividers - with a multimeter, I verified I was getting +15V and +12V as expected.
  • I then connected the amplifiers and dividers, and decided to first check the behaviour of each channel using the Fluke 6061 RF function generator and an oscilloscope. One of the channels (X-arm in the current configuration) worked fine - I got a 0-2.5V square wave as the output for input signals as low as -38dBm at 130MHz (consistent with out earlier observations).
  • The Y-arm channel however did not give me any output. In order to debug the problem, I decided to check the output after the amplifier first. The amplifier does not seem to be working for this channel - I get the same amplitude at the output as at the input. I verified that the correct DC power voltage of +12V was being supplied with a multimeter, but I am not sure how to debug this further. The amplifier is basically straight out of the box, and as far as I can tell, I have not done anything to damage it, as this was the first time I am connecting it to anything, and I repeated the same steps on the Y-arm as the X-arm, which seems to work alright.
  • The rest of the Y-arm signal chain was verified to be working by bypassing the amplifier stage (the attached photographs show the box in this configuration. There seems to be no issues with the divider part of the signal chain. 

Once I figure out the problem with this amplifier/replace it, the box is ready to be installed. 

 

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