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November 1999 Issue
Features

The Build: Don't Forget to Do the "Dishes"
Keep Your Antennas Trouble-Free This Winter
By John Bisset

• Dealing with snow and ice
• Inspect cable entry points
• Watch for nesting animals
• Keep an eye on pressures
• Static protection
• Bottom Line

What do a bottle of car wax, a wrench, some dum-dum and a permanent marker pen have in common? They are tools of the trade when it comes to getting your satellite dishes ready for winter. Before the really bad weather hits, take some maintenance steps to ensure reliable performance through next spring.

Let's begin out in the dish field, or what some folks call the "ant farm." If your dishes are mounted in a grassy field, has it been mowed? Are all weeds and saplings removed from around the dish mounts? Undergrowth provides dandy shelter for insects, birds and rodents. If allowed to grow and tangle with the mounts, the vines will hold moisture and promote rusting.

If a stockade fence surrounds your dishes, you can easily forget what's going on inside the stockade. While inspecting the fencing, go inside and look around. Take a can of hornet spray-not only for your own protection, but also to spray areas common to bee and yellowjacket nesting. These areas include the gate area, overhangs and the feedhorn. Bugs just love such areas. While you're looking for hornets, make sure the entry cap on your feedhorn is secured. If the entry cap is missing, be sure to replace it.

Dealing with snow and ice

If you're not prepared, this winter's snow and ice can play havoc with your satellite dishes. Just getting to them in winter conditions can be a challenge. Locating your dishes in a gravel field or on asphalt means you'll have an easier time gaining access to them if you need to fix or check something when a winter storm strikes. At the very least, providing stepping stones or a shoveled access path will make it easier to remove snow and ice from the dish.

So what about this snow and ice removal? Electric and gas-fired de-icers are the most effective but most expensive option; fabric dish covers also work well. A less expensive method is to polish the dish using auto wax. Applying the wax using a foam mop mounted to an extension arm works best. The idea is to polish the inner parabola of the dish with a thin film of car wax. The liquid wax works better than paste. When ice and snow start to build up in the dish, the waxed surface will permit easy removal with a broom or squeegee.

Now is a good time to assemble your snow removal tools, before winter strikes with a vengeance. Visit your local paint supply store to get an extendable pole or extension arm, which you can then use to apply the wax. Later, you can outfit the pole with a squeegee or broom for snow removal.

Snow and ice removal is a good job for entry-level technicians paying their "dues." However, be sure that they are given some instruction as to the physics of how the dish works. Banging on the front or back of a dish may ruin the parabola. Letting too much snow accumulate in the dish can distort the lower lip.

Make sure they understand that snow and ice removal is a "patient" job-brawn is not needed. Help them understand that ice formations left to sit in a dish can permanently damage it. When inclement weather strikes, make sure you assign someone to regular dish inspections and ice removal. Make it a part of their job description, so they understand the importance of keeping the dish clean.

Inspect cable entry points

As you inspect your flock of dishes, pay close attention to cable entries. Plugging the holes around these entry conduits with dum-dum or foam sealant will help to minimize problems stemming from moisture and insect intrusion. Sealing the entry into the building is just as important. You can use expanding foam sealant to both support a dual conduit run and also keep the elements outside, where they belong.

A pedestal mounted at the base of the dish makes for convenient cable runs back into the building. Check that pedestals are clean inside and locked.

While inspecting the mount, make sure ground wires are secure and bolts and nuts are tight. On fixed dishes, this is a good time to mark the dish with the permanent marker. When you know you have the dish properly peaked, draw a vertical line down the mount shaft. Because the line on the pole will align with the line on the mount shaft, if the dish shifts because of wind or vandalism, your technicians will be able to move it back into proper alignment quickly.

With your wrench, firmly tighten mounting bolts, inspecting for loose or missing hardware. Make sure that all the panels are properly aligned. Winter winds can deform dishes when mounting hardware is loose or missing. Replace rusted hardware now so that you won't have to hacksaw through a rusted bolt when it's 20° outside.

Watch for nesting animals

On Cassegrain dishes, inspect the back of the dish and the feedhorn tube for nesting animals. Squirrels especially like the security these structures provide, and they just happen to have a natural tendency to chew on cables, which can make your life a nightmare. Do what you can to seal these areas.

I recently noticed the problem of nesting animals on a 9.3-meter dish that was modified for multi-feed. The multiple cable runs inside the feedhorn tube made an excellent support structure for a squirrel's nest.

Keep an eye on pressures

While the weather still is tolerable, it's also a good time to check cable and feedhorn pressurization equipment. If you use desiccant crystals in a dehydrator, make sure fresh crystals are on hand. It's also important that the crystal condition be checked regularly. Moisture-laden crystals defeat the purpose of the dehydrator.

Larger air dryers need periodic inspection, too. Sticking pressure switches can cause the dryer to run frequently and unnecessarily, resulting in premature failure of the compressor. By labeling gauges, pilot indictors and fuses, you'll ensure that even the most entry-level technician can ascertain if the system is working properly.

Static protection

Although lightning is only occasionally associated with winter weather, dry snowfall and strong winds can cause potentially damaging static discharges. If your lines are not protected by some sort of surge suppression equipment, be sure to make that a priority.

Also, be sure to have replacement fuses on hand for your power supplies. I've Velcroed a small fuse box on the back of receivers, just so a supply of fresh fuses is readily available. This ensures that the right amperage fuse is used when the mad rush is on to get the receiver working.

If you do lose your power supply, there is a quick fix for temporary operation. The test points on some Scientific-Atlanta receivers can be used to back-feed DC voltage from a working power supply to a receiver that's lost its power supply. Of course, be sure to unplug the AC line from the "dead" power supply before adding the jumpers. There's enough capacity in the S-A supply to keep both receivers working until proper repairs can be made. For other makes, verify with the manufacturer that this type of temporary fix can be done without overloading the power supply.

We've all had those temporary "permanent" fixes to deal with. And while we're on the subject of AC for your receivers, if you make a temporary AC feed with an extension cord, be sure to use nylon cable supports and drywall screws to prevent the cable from accidentally pulling from the socket. Loop the cord near the top of the plug so you can easily pull the plug in the event of an emergency. Check local electrical codes before using extension cords in this manner because it may be prohibited.

By following these simple maintenance tips, you can rest assured that the pigeons won't be coming home to roost in your dishes!

John Bisset is a district sales manager for Harris Broadcast and can be reached via e-mail at .

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