Final Assembly
EMP Sensor Kit

In this phase, the PVC housing for the sensor will be assembled, the coax and ground wires attached, and the sensor installed in it's housing.

Note! - Important information on using PVC glue and assembly below.

Before you begin, you will need to obtain:

  1. A length of coax long enough to run from where you intend to mount the sensor to the interface board (depending on assembly options, the X1W-1 or X1W-2). RG-58 is easy to work with. RG-59 can also be used. Essentially any small diameter shielded cable will work. Coax is preferred since it is built to be used outside.
  2. A short length of wire, preferably stranded. #18 gauge works well. Usually 12" is more than enough. This will connect the sensor board ground to the mast on which the sensor will be mounted.
Ok
Procedure
  Use a pocket knife, file and/or sandpaper to smooth the edges on the ends of 3/4" PVC pipe.
  Locate the 3/4" end cap and glue to one end of the pipe. Don't forget to tap the two together lightly with a small piece of wood to insure the two seat correctly. Work quickly!. Wipe away the excess glue with an old rag or paper towel.
  Take the assembled sensor board/antenna and insert into the housing to check for clearances. The sensor should slide easily into the housing without binding. With the antenna seated against the end cap, the bottom of the PC board should be nearly flush with the end of the 3/4" PVC pipe with anywhere from 1/8" to 1/16" spacing between the bottom of the board and the end of the pipe. If the board is perfectly flush or it extends beyond the end of the pipe, you will need to trim the top of the antenna so that the 1/8" to 1/16" clearance is achieved.
  Remove the sensor board/antenna assembly from the housing and set it aside temporarily.
  The 3/4" coupling has a threaded and a smooth end. Glue the smooth end to the other end of the 3/4" pipe. As before, tap the two together and wipe away any excess glue. Remember, work quickly!
  In this step, two holes will be drilled in the plug. One to admit the coax and the other for the ground lead. The drill size used should be just enough to admit the cable and ground lead. For RG-58, a 7/32" bit is fairly close. RG-59 takes about 1/4" bit. In any event, check clearances by test drilling a piece of wood or some other material and checking for fit before drilling the plug. Do not drill one hole for both the coax and ground lead. Separate holes are easier to seal. Experience has shown that one hole is asking for problems later on.
  Pass the coax cable and ground lead through their respective holes in the plug and prepare the ends for soldering. The coax should have approximately 1/2" of the jacket removed. Seperate the braid and twist together to form one lead. Strip approximately 1/4" of insulation off the inner. The ground lead should also have 1/4" of insulation stripped off the end.
  Solder the ground lead to the outermost terminal on the sensor board. The inner of the coax should be soldered to the '+' terminal and the braid to the '-' terminal. Note that it may not be possible to possible to thread the twisted braid into the hole provided. If that is the case, flatten the twisted braid and tin with solder. The braid can then be sweat-soldered to the terminal.
  Even if your coupling is round, there is often a seam around the middle. On others, there is an hex "nut" molded around the middle. In either case, you will need to check that when the coupling is laid on a flat surface, it is flush. That is, it does not rock about the nut or seam. If it does, file one side until it does lay flush. This will become important later to insure a stable, solid mount on the mast.
  Slide the plug up on the coax/ground lead as far as it will go and insert the entire assembly into the housing as far as it will go. Clamp the plug in a vise as shown in the picture (or hold it stationary by some other means) and thread the housing onto the plug and finger tighten as much as possible. The purpose in putting the assembly together in this manner is to keep from twisting the leads going to the sensor board. Remember, only finger tight!

A couple of important warnings:
  • Don't glue the threaded assembly. You may need to replace the transistors or diode at some time in the future due to damage from a nearby lightning strike.
  • Don't use any lubricant on the threads. While it may go on easier, the fit is rather tight and the threads will seize up. In other words, you won't be able to get it apart again.

View of completed sensor assembly

At this point, the sensor should be checked once again for proper operation using the same procedure as before. When you are satisfied that everything is in good order, proceed with the installation.


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