Now it is time to examine each of the rectangles, one at a time, and to add to the schematic the other electronic devices (as rectangles) and all of the electrical connections and interconnections between the rectangles.  Some of these will be easy and intuitive, while some others will require a little more crawling around behind the equipment.  Every connection must be included; this is important to the integrity of the solution.  The only exception is a non-conductive fiber-optic connection.

Pick a starting rectangle and answer all of the following questions for that rectangle.  Then, pick the next rectangle and do the same.  Continue until all of the rectangles have been examined.

As we examine each rectangle we need to answer the following questions:

·        Is there a connection between this rectangle and any existing rectangle?  If the answer is yes, then add a line between the respective rectangles and label its function.

·        Is there a connection between this rectangle and a device not yet included in the box-level schematic?  This can include stand-alone amplifiers, power supplies, computers, terminal node controllers, modems, network routers, network HUBs, and the like.  If the answer is yes, then add the new distant device as a new rectangle to the schematic and label it.  Then add the connection between the respective rectangles and label it.  Repeat this step until all connections from this rectangle to new device rectangles have been completed.

·        Is there an ac power connection required for this rectangle?  If the answer is yes, then draw a line to the edge of the page and label it with the voltage and current required.

·        Is there a requirement for coax center-pin feed ac or dc voltage necessary to operate remote switches or tower top electronics?  If the answer is yes, label the already existing coax line at the edge of the page with the peak feed voltage and peak current requirements.

·        Are there control lines leaving the rectangle going to tower top electronics, relays, or rotor?  If the answer is yes, then draw a line to the edge of the page and label it appropriately.

·        Is there ac power leaving the rectangle going to the tower for safety lighting, convenience outlets, crank-up motors, or high power rotors?  If the answer is yes, then draw a line to the edge of the page and label it with the voltage and peak current required.

·        Is there a connection to a plain old telephone line, ISDN telephone circuit, DSL telephone circuit, or cable connection (RF, video, or data) for this rectangle?  If the answer is yes, then draw a line to the edge of the page and label it appropriately.

·        Is there a connection to another antenna system such as for GPS, over the air TV, CATV, or DBS satellite dish for this rectangle?  If the answer is yes, then draw a line to the edge of the page and label it appropriately.

Once we have iterated through each of the rectangles, including all of the new ones that were added, we should have an accurate box-level schematic of our radio station.  It may be prudent to re-iterate each rectangle to verify that nothing was left out.  Your box-level schematic should look something like one of the drawings above. 

The next step is to step back and physically look at the equipment in the radio room.  Has every piece of equipment been reflected in the box-level schematic?  Every metallic item within four feet (in all directions) of the radio equipment must be considered as a part of the radio equipment even if it is not electrically connected to it.  If there is such an item that has not been included, we need to carefully examine it.  An example of such a device could be a simple stand-alone telephone on the operating desk or a computer system (CPU, monitor, keyboard, and mouse) some part of which is sitting on or near the radio desk.

These near-by devices (telephone and or computer) while electrically not a part of the radio station, are by (spark-gap) proximity a part of the radio station equipment and therefore must be added to the box-level schematic.  Follow the same procedure that you used to add a transmitter, receiver, or transceiver to the box-level schematic.  An example of an included but not directly connected computer is shown in the accompanying drawing.

Now that the schematic is accurate and complete, draw a circle around all of the rectangles allowing each of the lines that extend to the edge of the page to penetrate the circle.  The equipment represented by the rectangles within the circle will be protected.  All of the lines going from the circle to the edge of the page are called I/O (Input/Output) lines or circuits.  Each of the I/O lines must be protected and each of the I/O line protectors must be grounded and mounted in common.  We will discuss how to do this in the next section.

Before we leave this section, the process that we have just used to identifying the equipment to be protected can be applied to any item or set of electronic equipment.  With some adjustment, it can be applied to tower top electronics such as preamps or power amplifiers; to a computer installation in another room, a TV, or a stereo system.  The principal is the same: identify all of the electrically and proximally connected equipment, identify all of the I/O lines, add protectors, and ground.  The theory is easy, the implementation can be challenging.

One word of caution regarding the accuracy and attention to detail; the protection is all or nothing.  If an I/O line is inadvertently missed then the protection plan is flawed and the damage could be worse than having no protection at all. 

Please note.  Just because the equipment can survive a direct lightning strike, does not mean that you can.  You cannot operate (touch) the equipment during the strike event because you  breach the protected equipment circle to the outside world.  You are conductive, and it could hurt both you and your equipment.