Transmitter Site Cleanup
Nov 1, 2014 9:00 AM, By Doug Irwin, CPBE DRB AMD
Consider the following scenario: You are tasked with maintenance responsibility for a new (to you) radio station and its transmitter site. After the first couple of visits, you start to notice some things that appear to be�shall we say�out of place. Should you demolish certain things and throw the pieces in a dumpster, or perhaps restore some of these �mystery� systems to service? Let''s take a look at some examples.
I have yet to visit a �new� transmitter site that doesn''t have a cabinet filled up with old spare parts. Naturally when you first discover them your inclination may be to keep everything. However, some items will clearly be obsolete. One station I visited had lots of spares for an old vacuum tube transmitter�yet was currently running two solid-state rigs, each of which was at least 10 years old. Verdict: remove or otherwise dispose of the old parts.
Some transmitter sites that once housed tube transmitters may also have old blower motors lying around. Typically those can go. Keep in mind they often have some salvage value.
On the subject of blower motors, one thing you might see around such a transmitter site is this:
This is a fan puller tool used to remove a squirrel cage (or other fan blade) from the shaft of a motor. Keep this one!
Another feature one often sees at some sites is an old exhaust blower either in the ceiling or right over the door. Does it work? What is it for? This may have been part of an �old-school� cooling system. Think about it�20 years ago before solid-state transmitters and computers made their appearance at the transmitter site, air conditioning wasn''t as commonplace as it is today. There was not as much need to keep the transmitter space nice and cool. Many sites simply relied on exhaust blowers.
Can this system still be useful? At the very least, it could function a backup cooling system if the �new-fangled� air conditioning system should fail for some reason. Test the old system. Find the thermostat, run the setting to a lower temp, and see if the fan comes on. If not, see if you can make it work. If you have one of the fan blade pullers I described earlier, you''ll be glad you kept it. It makes changing the blower motor much easier should that be necessary to make the system functional.
Most likely you have a temperature sensor of some sort connected to a remote control, right? You might want to consider adding an air switch or perhaps a current sensor to the exhaust fan system. Connect this sensor to the remote control. This way, if you get a call or message from the remote control indicating that the room temperature is high and the exhaust fan is on, you''ll know your air conditioning may have malfunctioned.
Another item typically found at sites is one or more boxes of air filters. Did they go with the tube transmitter that made its exit 10 years earlier? If so, clearly they''re garbage. Before you throw them out, however, look for any old and forgotten air inlets carved into the exterior walls. Sometimes desks, cabinets, or other boxes get pushed up against them. �Mystery� filters could have been used on these air inlets, hopefully on the north wall of the building. Once an air conditioning system is installed, often old system remnants such as these are forgotten. These air inlets are part of the same system as the exhaust fan I mentioned. Remove any old, rotted filters and replace them. Move stuff away from the walls so that these air inlets aren''t forgotten again.
Here''s another familiar sight:
Old transmitter sites often have components of abandoned alarm systems. If your transmitter site is shared in some fashion, clearly you''ll want to know when someone other than you goes in and out. One option is to remove these abandoned components as part of site cleanup. On the other hand, you could connect these sensors to your current remote control and configure an alert that tells you when the door opens or closes.
These are just a few things that you could do to make a �new to you� site a bit cleaner and more reliable. Do you have any tips for making old sites new again? What is the strangest thing you have ever encountered at an inherited transmitter site and how did you deal with it? E-mail your stories to email@example.com.
Irwin is RF engineer/project manager for Clear Channel Los Angeles. Contact him at firstname.lastname@example.org.
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