Switched Attenuator

This page details the switched attenuator that I made for use on a radio foxhunt a few years ago. This was my first attempt at a construction project as an M6. There is a lot of things I could of done better.

I managed to fin the fox hunt even though there was only two of us taking part. I had some help on the map and overall it was very enjoyable. See this article posted on my clubs website.

I found some designs online for different versions and methods of making an attenuator. In the end i decided to go with this one.

Components:

  • 5 Double Pole Double Throw Switches
  • 15x Resistors various values
    • 2x 470ohm
    • 2x 300ohm
    • 2x 200ohm
    • 2x 100ohm
    • 2x 68ohm
    • 1x 12ohm
    • 1x 18ohm
    • 1x 33ohm
    • 1x 75ohm
    • 1x 270ohm
  • 2x PL259 panel mount sockets

Tools Required:

  • Small Drill bits
  • 17mm diameter drill (hole for panel mount socket)
  • Soldering Iron and Solder
  • Small nuts and bolts (Fix panel mount sockets)

Build Method:

First step was to solder the resistors to the switches. The top two connections (position 1) are simply connected together. The bottom two
(position 2) have the connections to the resistors. Below is a diagram showing this.

Diagram of the switch assembly for the Switched Attenuator
  • Switch 1: R1, R2 = 470ohm, R3 = 12ohm
  • Switch 2: R1, R2 = 300ohm, R3 = 18ohm
  • Switch 3: R1, R2 = 200ohm, R3 = 33ohm
  • Switch 4: R1, R2 = 100ohm, R3 = 75ohm
  • Switch 5: R1, R2 =  68ohm, R3 = 270ohm
Image of the assembled switches for the Switched Attenuator

First I Drilled and fitted the switches and the panel mount sockets into the enclosure. I then fitted a link wire between the outer braid side of each socket and then soldered the other end of R1 & R2 of each switch to this.

Next I connected the center pins of each socket to the relevant input connection on the first and last switch.

Finally, I soldered jump links between each switch.

Images of the assembled Switched Attenuator

This is a very simple method of making an attenuator and my attempt being my first does not look the best but it performed well when used on the Foxhunt.

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