Shack Board v1

This v1 Shack Board can provide power for PreampA, PreampB and SAPreamps as well as interface from each of their outputs.  However the interface is passive by way of transformers and while quiet does not produce the common mode rejection of the later, v2 design. This design contains a diplexer which allows combining two different antenna/preamplifier units to create a Hybrid antenna system. It will generally not be used except for this specific case.

Power for the supported preamplifiers is provided from the input 10-16 VDC regulated with an adjustable LDO to produce 8V at the preamp, after any voltage drop in the intervening CAT5 cable

Features

  • Provides power and interface for all preamps; PreampA, PreampB & SAPreamp.
  • Receives one or two pairs of CAT5 RF from an associated preamplifier
  • Preamp input buffer bias switch to verify system common mode performance
  • Completely passive. approximately 0 dB conversion gainfrom 100 ohm CAT5 to 50 ohm output
  • may also be used for initial testing of Preamps, Junction Box and cables.
  • Front Connections:
  • SMA: 2 one for each of A and B CAT5 lines
  • Rear Connections:
  • 2.1mm barrel connector for power
  • RJ45 for CAT5 to preamp(s)
  • External supply voltage 10-16 VDC, current depends upon Preamp selection
  • Double-sided, 4-layer, silk-screen PCBs

    • Testing

    This PCB may also be used for initial testing of Preamps, Junction Box and cables.
    There are also switches on the PCB to allow verifying proper preamp performance.

    Since assembled PCBs must be ordered with minimum quantity = 2 , this makes a good arrangement for testing. Using each of two PCBs as a simple 50 Ohm <==> 100 balanced line adapter lets transmission through a length cable be measured. Applying power to either of the interconnected boards also allows checking power function of each board.
    DC tests can be performed with a multimeter for power supplies. For RF testing a broadband measurement using a scalar or network analyzer is a very good method. This may be done with a TinySA or nanoVNA. Loss through the system during a two-Shack board test should be near 0 dB. Typically CAT5 cable loss should be about 3 dB/30m at 30 MHz.
    Initial version of the Shack Board with diplexer included.

    Use

    In addition to its main function of supplying power to Preamps and receiving differential RF over CAT5 cable and delivering the filtered/combined results to a receiver, this board also has a switch to disconnect the 12V supply from the input circuits of a probe preamplifier while leaving output stages operative. This is useful for identifying common mode and other unwanted noise ingress apart from the intended balanced antenna.

    Diplexer/combiner frequency response:


    Material List

    What you will need to build this hardware

    Item Description

    Provider

    Source Code

    Notes

    Approximate Material Cost

    (excludes setup fees and shipping)

    Assembled ShackPCB PCB

    Download ShackPCBv1 Kit Files

    ==> JLCPCB

    Download ShackPCBv1 Source Files

    ==> KiCad

    		 Added Preamp12V/LED and shorting relay switches
    		US$

    38x88x100mm Clam Shell Enclosure

    eBay
    		Other sources possible. Enclosure needs to accept 84mm wide PCB. US$12

    38x88mm ShackPCB Front Panel

    Download ShackPCBv1 Front Panel Kit Files

    Download ShackPCBv1 Front Panel Source Files

    		 Select 'Aluminum" when ordering. These are panels only no components.
    		 US$1

    38x88mm ShackPCB Rear Panel

    Download ShackPCBv1 Rear Panel Kit Files

    Download ShackPCBv1 Rear Panel Source Files

    		 Select 'Aluminum" when ordering. These are panels only no components. US$1

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