Initial Assembly
X1W-4 EMP Sensor Kit


Refer to the layout diagram for clarification of parts placement. All references to up, down, left, and right assume that you are looking at the PCB with the silkscreen TAPR logo on the left-hand side of the board. Unless noted otherwise, all components are mounted on the top of the PC board. If possible, use a piece of anti-static foam to lay the board and components on during assembly.

  Inventory the parts if you have not already done so. Make sure you identify and account for each.
  Position the board as shown in the component layout with the TAPR logo positioned on the right. Note that the image as it appears in the browser is oriented with the logo at the top of the page. This was done to facilitate printing. You will find it easier and far more convenient if you print the layout and place it with the logo oriented to the right while assembling the kit. All parts are installed on the top side of the board.
  Check your soldering iron to be sure the tip is in good condition. The tip should be the small screwdriver tip type and must be clean. If you can't remember when you last replaced the tip, now would be a good time to do so.


Resistors are mounted flat near the surface of the board and will be installed first. Do not solder or clip leads until instructed to do so. Be careful when clipping leads, as they could fly towards your eyes! Take appropriate precautions (grasp leads and wear eye protection). Save a one of the clipped leads for a jumper later on in the assembly.

  R1 - 100K, 5% (brown-black-yellow-gold)
  R2 - 15K, 5% (brown-green-orange-gold)
  R3 - 1M, 5% (brown-black-green-gold)
  Solder and clip six leads. Wear safety glasses and observe proper precautions!


  D1 - 1N4148 switching diode
  Solder and clip two leads. Wear safety glasses and observe proper precautions!

Install Jumper

In this step you will use the clipped resistor lead saved from an earlier step. It will be used in place of L1. If you elected to get the additional parts and install the low-pass filter circuit, then the 2.2 mH choke needs to be installed at L1 and the 10 pF capacitor at C1. If you do this, skip the steps below and go on to the next section, Transistors.

  Install jumper at L1
  Solder and clip two leads. Wear safety glasses and observe proper precautions!


These are polarity sensitive devices. If installed wrong and voltage is applied, they will be destroyed, even if for less than a second. Be certain they are correctly aligned with the silkscreen pattern before soldering.

Installation Instructions
1 Spread the legs of the transistor so that they align with the holes on the PC board with the flat side lined up with the silkscreen outline on the board. Note that the center leg is pushed back, away from the flat side.
2 Push the transistor into the board so that bottom of the device is approximately 1/4” above the board. Do not over-stress the leads. If you encounter resistance as you push the transistor in the mount holes, stop.
3 Spread the legs apart slightly on the bottom side of the PC board to hold the device in place.
4 Solder and clip three leads. Wear safety glasses and observe proper precautions!

Install the following devices using the procedure outlined above:

  Q1 - 2N3904
  Q2 - 2N3904

The picture shows the completed board prior to attaching the antenna section.


There are two ways to prepare the antenna for mounting. Choose the method that best suits your skill level and experience. The first method is the easiest and will work fine. However, if you have the tools and skills to perform this operation, it will provide the strongest mount of the antenna to the board.

The solder areas of the PC board where the antenna will be attached are the two large square traces (top and bottom) of the board on the left-hand side. This is the side where the TAPR logo silkscreen is located.

Method #1 - Using a hacksaw, or tool of your choice, cut a semi-circle of pipe back 1/2". See the picture for an example.

Method #2 - Using tools of your choice, cut a slot 1/2" deep so that the pipe fits snuggly on the top and bottom of the PC board.

Using a vise to hold the copper tube and/or PC board, sweat solder the pipe to the top and/or bottom bottom traces of the PC board. Because the copper pipe will act as a heat sink, a high-wattage soldering iron or soldering gun will be required. You will also need to thorougly clean the copper pipe so that it is bright and shiny in the areas where you will solder. Use of soldering flux or some other chemical soldering aid for electronic soldering is recommended.

  Prepare copper antenna pipe for mounting using method #1 or #2 above.
  Tin the copper pipe along the edges where it will be soldered to the PC board.

  Solder copper antenna pipe to the PC board. If you prepared the pipe using method #1, either side of the PC board will work. The first picture shows board and pipe as prepared for in method #1. The second image shows the completed solder job.

You are now ready to proceed with the board check.

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