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• frequency_generation_box

RF Generation Box

The 40m Upgrade Frequency Generation Box is going to be installed in the 1Y1 rack. It will be used to generate the modulation and the demodulation frequencies.

Some Thoughts in Early Days

• This box will be made from a Metalcraft 2U chassis.

• This is an inspirational model.

• The box will contain a crystal oscillator to generate the 11 MHz sideband. From that a frequency multiplier will provide the 55MHz modulation.

It will be possible to opt between an external source of the 11MHz modulation rather than the internal oscillator.

• The box will also provide the signals for the demodulation at the LSC rack.
• The amplitude of the modulation signals going to the EOM will be tunable by means of two mechanical knob-attenuators and by Voltage Controlled Attenuators (VCA).
• The front panel will have the following inputs:
  • 11 MHz
  • 11MHz VCA
  • 55MHz VCA
• This will be the outputs in the front panel:
  • 11 MHz to the EOM
  • 11 MHz to the LSC
  • 55 MHz to the EOM
  • 55 MHz to the LSC
• the front panel will also host knobs of the two attenuators.

Pictures

• This is the current state of the RF Generation Box (picture date: 6May2011). A high resolution version is here RF_Source_picture_hires.jpg

• 

• The schematic diagram of this assembly is shown below. The graffle original is attached as a zip file. The pdf version allows high resolution.

• 

List of things to do

1. Characterization using Blue Phase 1000 test-setup.

   • Follow the steps given in Blue Phase 1000 User Manual: Single Channel Two Source Phase Noise measurement, as given in section 3.5.3 of its user manual. The data sheet of a typical Wenzel oscillator of the type we have is here. The data sheets (hard copies) of the two that we have are available in the lab and they should be scanned and attached here_1 and here_2.

   1. Wenzel Oscillator phase noise measurement
      1. Since we have two 11.065 MHz Wenzel oscillators we can use one as the reference source and the other (installed) as the Device Under Test (DUT) and follow the steps given in Section 3.5.3 mentioned above.

      2. For the 55 MHz RF Generator Box output, we may have to use the 3-corner-hat method described in this elog

   2. Amplitude noise measurement: For 11 and 55 MHz outputs: The same steps as in the phase modulation measurement but with the source and reference being the DUT (split the signal using a splitter)
   3. write a LIGO technical document

Parts

RF Generator Parts

RF Components

Box Assembly Parts

DC Powersupply Parts

Bulkhead Mounted CPC Connector

DC Voltage Input

Dsub connector, 9pin, female socket.

DigiKey: A32510-ND

Front and Back Panels

Front and back panel prototype designs

Front and Back Panels files for FrontPanelExpress 4.02.

Back Panel

Front Panel

Links

Chub's Web Page with lots of electronics diagrams and pictures