(click thumbnail)Fig. 1: This cable tray supports the line until it exits the building.
(click thumbnail)Fig. 2: Kindorf and other electric supply hardware eliminate any chance of line sag.
(click thumbnail)Fig. 3: Clamp-type couplings simplify installation and measurement.
(click thumbnail)Fig. 4: Jeff Caudell, shown, and Ben Brinitzer planned this Class A FM site.
(click thumbnail)Fig. 5: Nice job on the wiring.
(click thumbnail)Fig. 6: P-touch labels and wire ties make it easier to work on these distribution amp racks.
(click thumbnail)Fig. 7: Use a labeling machine to identify disconnects and other important locations.
(click thumbnail)Fig. 8: A neat shop makes you look good. I've been fortunate during the past year to receive and share a number of pictures of problem sites with readers of this column. To be fair, these sites are in the minority. So to give balance, I'd like to focus this column on things that were done right.
Admittedly the pictures aren't as much fun, but I hope they'll give you good ideas on ways to improve your facilities.
Lewis and Regina Moore own an FM in Jonesville, Va. Lewis, who works for the phone company, knows all about cable trays and specified a tray (Fig. 1) from the manufacturers of his pre-fab concrete building, VFP (www.vfpinc.com). The vertical run of his rigid line was cut to permit the flex line to lay in the cable tray. The cable tray provides adequate support of the line till it exits the building.
. . .
Support of transmission line is important. Fig. 2 shows Mark Bohnett's support system at WESM.
This line isn't going anywhere. Using Kindorf and other electric supply hardware, typically used to support conduit, the support systems eliminate any chance of line sag. Note how Mark used rubber bushings inside the clamp assembly, to prevent any damage to the outer conductor of the rigid line section.
. . .
Rigid line assembly and routing inside the transmitter building (all unpressurized) is simplified using couplings held in place with hose clamps. Having to cut and solder flanges on each end of an inside rigid run is time consuming, and though the finished product looks nice, measurements must be precise.
The clamp-type couplings, shown in Fig. 3, are more forgiving with regard to measurements, in addition to being easier to install. When using these couplings, it's important to clean both the inner and outer conductors with Scotchbrite, removing the oxidation, and leaving shiny copper surfaces. Push the ends together, center the coupling, and tighten the hose clamps.
. . .
Clear Channel Harrisonburg's Jeff Caudell worked with his regional engineering manager, Ben Brinitzer, to plan the Class A FM site shown in Fig. 4. Note that Jeff also used the ceiling cable tray to manage some of his rigid line as it goes to the transfer switch.
The back of Jeff's equipment rack is shown in Fig. 5 - some really nice wiring. Because the station upgraded transmitter power, Jeff brought the transmitter remote control wiring out to an interface panel (below the remote control). This allowed pre-wiring of the remote control cabling before the new transmitter was set in place, reducing downtime while the transmitter swap was made.
. . .
The time it takes to wire a system properly and neatly can pay dividends when troubleshooting. Fig. 6 shows a series of DA distribution amp racks wired with multipair cable. Note the P-touch labels that identify each multipair line. Lacing or tying wires once the installation is complete makes testing or removal of a DA simpler. You're not reaching into a rat's nest of wires to sense a signal, and the ties usually hold wires in place, so nothing gets incorrectly connected when the DA is returned to service.
. . .
Labeling machines are inexpensive enough that every engineering department should have one. Note how the label on Fig. 7 stands out, quickly identifying the disconnect.
. . .
Inexpensive shelving, found at Lowes or Home Depot, can be used to organize your shop as well. There's no question where test equipment is located in the shop organized by Orlando, Fla., broadcast engineer Dennis Sloatman.
Looking for respect from your management? It's harder to earn that respect if your shop is a haphazard mess. You may be the best engineer in the region, but if your shop is a disaster, you're sending the wrong message to your manager. As we start with a new year, set aside a day to organize your shop and office. Watch how it pays off for you.
Submissions for this column are encouraged, and qualify for SBE recertification credit. Fax your submission to (703) 323-8044, or send e-mail to firstname.lastname@example.org.