First, measure the footprint of your speakers, which is just the width and depth of the bottom of the speaker. You usually want to match that pretty closely with your stand; too much excess and the stand looks like it was made for larger speakers (and we don’t want that!). The stand tops shown in Figure 9-1 are 8 inches wide and 8 inches deep.

These stands are about as simple as you can get and still look quite good. Once you have the base of your speaker measured, obtain some 3/4-inch-thick, medium-density fiberboard (MDF). Cut two rectangles to your speaker measurements, and then cut two more squares slightly bigger (for example, two squares might be cut at 8 x 8 inches, and two more at 10 x 10 inches). The smaller squares are for the speaker base and the larger ones are for the stand base.

Next, cut four longer rectangles; these should be about 2 inches less deep than your speaker base. So, if you have a top plate that is 8 inches deep, these rectangles should be 6 inches deep. To obtain the height, you’ll need to know how high you want your speaker to sit. Then, just subtract 1 inch, and cut to length.

Figure 9-1. Basic speaker stands

So, these might be 6 inches deep and 30 inches wide (for example). Two of these become the connectors for one stand and two for the other. At this point, if you’re able, bevel the long edges of the connectors. You also should round all four edges of the tops and bases. This will really add a polished, classy look to your stands, and allow the base of the stands to sit more firmly on the floor.

With the rounded sides up on both the top and bottom plates, the two long pieces should be evenly spaced, centered, and then angled slightly (see Figure 9-1 as a reference). Now, glue and nail in place. All that’s left is to paint the stands; prime first, and then lay on a couple of good coats of black, or whatever other color you prefer.

If you’ve got heavier speakers, you might want a sturdier design. This design also works well if you need your speakers quite high; the basic stand sometimes looks a little wobbly as the connector pieces get really lengthy. The basic procedure is similar, with just a few twists for stability.

First, I’ll assume you’ve got larger speakers—mine for this job were 16 x 10 inches in footprint. So, my tops were a bit larger than in the basic stand. Again, round the tops. The base follows the same process; in this case, my bases were 18 x 12 inches, also rounded.

Instead of long connector pieces, though, I made a square “box” out of MDF (again, 3/4-inch thickness is fine). This box was half the depth of the top—in this example, 5 inches—and the height was calculated as shown in the basic stand section. To add a nice look, the edges of the box should be sanded slightly round, to look less...well...boxy. Glue and then nail this box to the base of your speaker; I set mine in the shape of a diamond for slightly more visual interest (see Figure 9-2).

Figure 9-2.  Sturdier speaker stands

Now glue and nail on the top. Before you finish up and paint, though, drill a hole in the center of the top plate, which opens into the box that acts as a support. Now prime and paint. However, before putting these stands into action, fill the box support with sand. This really solidifies these stands, allow them to hold heavier speakers, and even look more substantial.

Believe it or not, it cost about 30 bucks to make all four stands! Online, similar stands ran from $30 a pair (on the low end; and this is only for two) to hundreds of dollars in higher-end shops. Clearly, this is a no-brainer way to get into DIY and save some bucks. Also, don’t be afraid to get creative. If you don’t have a lot of tools, find materials you can work with that don’t need much in the way of tools. Buy premade shelves and have the hardware store cut them to the sizes you need. Substitute threaded rode (the line you typically see attached to the anchors of small boats) or PVC pipe for the center supports. Add door or corner moldings to get a different look. Whatever you can come up with that gets the job done and saves you money will represent a successful project.

—Dustin Bartlett

Here’s what you need:

The directions that follow will produce the same stand pictured in my home theater (see Figure 9-3). Of course, you can make any changes you want to produce a different stand.

Figure 9-3. DIY TV stand

Building a basic screen isn’t much more difficult than building speaker stands [Hack #75] . That might seem hard to believe, but a screen is just wood and fabric. If you can build a simple wooden frame and can follow some simple canvas stretching techniques, it’s a piece of cake.

Begin by getting some 1/4-inch flooring plywood. Cut the plywood to your desired screen size (note that this technique limits you to a 48-inch-tall screen). You’ll also need some 3/4-inch pine shelving material that you should cut into 3 to 4 inch wide strips, sized to make a frame that will mount on the plywood.

I chose to construct the frame using simple but very strong fishplate joints. Figure 9-4 shows 1/4-inch cuts into the pine on each side, with a piece of plywood for connecting the two edges.

Once you’ve glued the joint, use a staple gun to sturdy things up (see Figure 9-5).

Now, you can mount this entire frame on your plywood, as seen in Figure 9-6. The plywood makes this frame very rigid and provides numerous options for hanging the screen. I’ve had success cutting a couple of small square handholds in the plywood. This makes the screen easier to handle and provides a perfect fit for 1/4-inch mirror hooks. I’ll leave it up to you to determine the best way to mount the mirror hooks to your wall, or let you come up with another method that works for you.

Before you start stretching the fabric I also recommend sanding down the outside edges of your frame to round them off. This reduces the chance of ripping the fabric you stretch over the frame. If you have a router, I also recommend rounding off the inner edge of the frame to prevent it from pressing against the fabric. If you don’t have a router, sanding will have to do. Now you need to add fabric. Plain white blackout fabric will work, and you can get this at any fabric store. If the salesperson doesn’t know what you are talking about, ask for the fabric that backs curtains to prevent light from passing through. Lay out the fabric on a flat surface, cloth side down, and then place the frame on top; make sure you’ve got at least one inch of excess fabric on all four sides of the frame, and if you’ve got significantly more than that, cut it off and discard. Also, smooth out any wrinkles.

Figure 9-4. Fishplate joint with pine and plywood

Figure 9-5. Completed joint

Figure 9-6. Frame with borders and bracing

Fold one side over the frame, and tack the fabric to the frame in the center of the side you’re working on. Do not add any other tacks at this point. Now stand the frame up so that the side tacked in is on the bottom (against the floor). You should be able to stretch the fabric opposite the tack over the frame, until there is a slight crease in the fabric. This tells you things are just tight enough. Tack in the fabric.

Now you can move to one of the two remaining untacked sides, and repeat. Then, tack in the final side; at this point, you should have a sort of diamond formed from the creases, running from one tack to the next. Now, you’re ready to get out your staple gun. Start in the center of one side, slowly move out a few inches, and staple. Then repeat, in the opposite direction. So, you’re always moving out in one direction, stapling, and then moving out in the other direction, keeping the tension even and the creases moving toward the corners.

When you get to the corners tuck one side under and fold over, and you’re all set (see Figure 9-7).

Figure 9-7. Completed screen with staples in

Finish up with the stapling, and you should have a great, taut fabric, as seen in Figure 9-8.

This is but one method for building a screen. I found it easy and effective. I’ve seen examples online of screens that ranged from simply hanging a piece of Parkland plastic on your wall, to frames made out of PVC, all the way to guys with the skills to weld an aluminum frame. There’s no single right solution to most problems and that’s the beauty of DIY. Copy exactly what someone else did, come up with your own unique solution, or do something in the middle. With DIY, you’re the client, engineer, worker, and boss, all in one.

Figure 9-8. Completed screen

—Dustin Bartlett

There are three types of adjustable masking systems: constant width, constant height, and constant area. Most people run a constant width, some run constant height, and a few run constant area. In my opinion, constant area is by far the best option.

The masking is quite simple. Cut a strip of 3/4-inch laminated pine (or other appropriate wood of your choice) to the width of your screen, plus a few inches (so, perhaps, 100 inches for a 96-inch-wide screen). Then affix black masking cloth, or blackout cloth, to it. This serves as the bottom mask. Your top mask will be a valance that will house a curtain rod for the vertical masks and a roller for the horizontal mask (more about this later). The valance and the fixed bottom mask will be attached using two strips of pine such that they will form a slot your screen will fit into. With the bottom mask acting as a ledge, you can get away with using Velcro to mount the screen into the masking system. One advantage of this system is you can keep the screen out of harm’s way while you mount the masking to the wall. Once the masking is mounted and the screw, drills, and other dangers to a screen are gone, you can bring the screen in and drop it in place.

Now, back to the valance. This involves framing out the sides and top, coming out from the wall several inches (see Figure 9-9), also with pine. Within this valance, attach a curtain rod (see the figure again for a visual aid). This curtain rod will connect to and control the vertical masking.

Figure 9-9. Valance, curtain rod, and top assembly

Attach some blackout curtains to this curtain rod for use as your side masking. I’ve sewn a piece of straight steel (light, but inflexible) into the inside edges of the curtains to ensure they hang straight and form nice straight vertical masks.

The last step is to add the horizontal masking (which reduces the effective height of the screen); this is where things get a little tricky. The horizontal mask is wound on a roller that feeds out underneath the top curtain rod (you can see this in Figure 9-9, as well as Figure 9-10).

Figure 9-10. Horizontal masking assembly

This roller is made of 1 1/4-inch Electrical Metallic Tubing (EMT) pipe. I’ve hammered into the ends of the pipe a 1/2-inch piece of circular plywood, with holes drilled in them to accept 1/4-inch bolts and T-nuts on the inside. The T-nuts are there to provide something very solid for the bolts to screw into. This essentially creates a roller that I can easily set up to rotate. On the side that will not have the cranking mechanism (the left in my theater), thread a 1/4-inch bolt (one that isn’t threaded all the way to the top) through a hole you’ve drilled in the outside of the valance, then into the plywood in the end of the roller, and finally into the T-nut. Don’t forget to put a washer, lock washer, and nut on the bolt before you thread it into the plywood in the end of the pipe. You’ll use this to lock the bolt to the roller, making it so that they turn together.

The right side will need a little more hardware. Here I recommend using a 1/4-inch stove bolt (a bolt that is threaded all the way to the top). Again you’ll need to drill a hole in the valance to accept this bolt. On this end, though, because the stove bolt is threaded all the way, I mounted a T-nut that was too large for a 1/4-inch stove bolt to the outside of the valance to prevent the bolt from wearing away the wood. Use the same means as the noncrank side to lock this bolt to the roller so that they turn together. On the inside of the valance, put two nuts (turn them together tightly so that they won’t move) and a washer. These two nuts and a washer serve two purposes. The first is to prevent the roller from sliding too much from side to side. The second is to provide a support for a wing nut on the outside of the valance to tighten against and stop the roller from turning, without popping out the wooden plugs in the rollers in the process. Finally, rig a simple hand crank to the stove bolt on the outside of the valance (see Figure 9-11).

Figure 9-11.  Crank assembly

Next, wind black masking onto this pipe, and sew another steel piece into the bottom of the masking (I used 3/4-inch EMT pipe for this purpose). This will ensure the masking hangs evenly with a straight edge, and winds down when needed.

Granted, this is no remote controlled, motorized, four-way-adjustable masking system that uses magnetic stop points (there are plans on the Internet for masking of that type). It was, however, an effective solution that fit my wants and budget, which was less than $200. Even pictures of just the screen with the lights on show the rather drastic improvement adjustable masking can provide. See Figures 9-12 and 9-13.

—Dustin Bartlett

Figure 9-12.  Masking setup for 2.35:1 format

Figure 9-13.  Masking setup for 4:3 ratio

All you need for this project is some CAT 5 cable. I recommend either Anixter (http://www.anixter.com) or MECI (http://www.meci.com) as a supply source. You should order 50% more cable than you plan to use. In other words, if you need a 100-foot cable run, order 150 feet of cable.

You’ll also need spade connectors or banana connectors (it’s a personal preference as to which you like better). You can find some decent spades (Part #091-395, #093-546, #093-547, #093-550, or #093-551) or bananas (Part #091-1165 or #091-1260) at RadioShack.

Cut 14 pieces of the CAT 5 to a length of 6 feet (I needed about 5 1/2 feet, and allowed for some shrinkage of length due to braiding). Remove the blue PVC jacket (you might have to do it a foot at a time), and remove the twisted pairs.

Simply secure the cable at one end and pull the rip cord through the PVC, and you should be in business. At this point, leave the pairs twisted. You should now have 56 pairs of wire (112 wires). You won’t need two of the 56 twisted pairs; this project needs only 54 pairs. Next comes the fun, and time-consuming, part.

Take three twisted pairs and secure with a bench vise (or any other method that provides tension on one end of the cable). I actually used a heavy duty staple gun and stapled the three pairs to a vertical wooden doorjamb. Next, braid the three twisted pairs. Starting with the left pair placed between the center and right pair, and then the right pair placed between the left and center pair, continue back and forth until you have completed the entire length. Try to braid the pairs as tightly as is reasonably possible to yield the lowest possible inductance. However, do not go overboard with the tightness on these initial braids. I found that there should be about a 1/16-inch gap (at its widest) between twisted pairs. A good idea is to practice on a short length first to get your technique down. You do not have to braid the last 5 inches or so, as you will need to strip the ends of the wire later on and you will need to have these “pigtails” to span the distance between binding posts.

Start the next batch of three twisted pairs and continue until all the wire has been braided. Now you should have 18 braids containing three twisted pairs each (six total wires per braid). Now take three lengths of your braided beauties, and braid these together reasonably tightly. Now you should have six braided lengths containing nine twisted pairs (18 wires). At this point you should be an expert at braiding, and will welcome the fact that you have only two more braids to go.

Next—you guessed it—take three of the six lengths and braid those together. Now braid the last three together. You should now have two lengths of 27 twisted pairs of wire (54 wires). One length is for your right speaker channel, and the other is for your left speaker channel.

Your next step also will be time-consuming, and an absolute bear on your fingers, but trust me, it will be well worth it. Each twisted pair within each braid will have one solid color-coded wire and one striped color-coded wire.

Separate and group together all the solid wires and then do the same for the striped wires. You might have differences in the lengths of these wires; just go ahead and cut them so that they are all about the same length (in other words, the ends of the wires all match up). Now strip about 1 inch of insulation from the ends of all the solid wires, and twist them all together tightly. Do the same for the striped wires, and then continue with the other ends of your cables.

At this point all you need to do is check to make sure you really have all the solids with solids and striped with striped by checking with a multimeter or continuity tester.

Now all you have to do to complete your speaker cables is to terminate them with your spade or banana connectors.

Make sure you note whether the solids or striped wires are positive polarity, and be consistent with your other cable channel, or you will have your speakers running out of phase with each other. This will be easy to hear because your bass response will suffer dramatically.

That’s it, you’re all done. Now you have very low-inductance speaker cables that are equivalent to 10-gauge! It took me an entire weekend to construct these cables, but they’re worth it. If you want, give them a while to break in before giving a seriously critical listen (but see [Hack #25] —Ed.).

Several factors influenced my design, and in particular, why I chose this approach. This is the high-end techno-babble, so if you’re not into cable construction, you probably won’t be interested in much of this.

—Chris VenHaus, VH Audio

The parts list is identical for both flavors of power cables.

You can purchase all of these components online from VH Audio at http:// venhaus1.com/VH_Audio_Test.html. If there are additional components for a specific design, they will be listed in that section of the hack.

This approach works best for your grounded digital components. The design is illustrated in Figure 9-15.

Figure 9-15. Grounded digital component power cable design

Here’s what you need to do:

I found the following design, shown in Figure 9-16, worked best with my analog components and most amplifiers.

Additional notes.

Use the unshielded version of the VH Audio wire. This lowers the capacitive coupling even further between hot and safety ground. Additionally, ensure that there is more than 1/8-inch spacing between the safety ground and inner conductors by using the heavy-walled, high-pressure air hose as a spacer. Combined with the shield removal and the counter-spiraled ground, I believe this design can achieve the absolute lowest capacitive coupling between the inner conductors and safety ground. The end result of this design has a diameter of about 5/8 of an inch and looks really serious, especially with the nylon sleeving over it (see Figure 9-17). Your friends will ask, “Why do you have garden hoses attached to your stereo components?” Just smile and tell them you built it all by hand!

Figure 9-17. Completed power cable

This design is intended for components that don’t need a ground; the design is shown in Figure 9-18.

To make an ungrounded cable, simply follow the steps in the “For Grounded Digital Components” section, and don’t add a safety ground (Step 9). Just use the raw VH Audio shielded cable (no need to use or wind a 12 AWG safety ground).

Figure 9-18. Ungrounded design

In this design, it is very important to place a separate safety ground outside the twisted pair conductors to decrease the capacitive coupling between the hot lead and the safety ground (as opposed to using a safety ground within the hot/neutral conductor bundle). This can minimize the chance of leakage current causing bad “gremlins” to invade your component, which is, of course, a good thing.

I also found it was best to connect the braid/foil shield only to the ground, and not to the component itself. Once again, this is to help keep the “buga-boos” moving in the right direction—away from your component and toward ground. I believe this braid/foil shield also has the benefit of further buffering interactions between the hot lead and safety ground. By spiraling the safety ground in the opposite direction of the twisted conductor pair, we further mitigate the effects between the hot and safety ground.

Something I found to be very interesting was that no single construction method sounded best on all components. The components I used seemed to prefer one method or another. Please be sure to follow the right recipe for your component to get full performance from these power cords.

Lastly, after extensive listening tests, it seems these cables need to “cook” for about 100–200 hours to reach optimum performance (but see [Hack #25] —Ed.).

—Chris VenHaus, VH Audio

When two identical antennas are mounted together, or ganged, pointed in the same direction, and wired together properly, there is a theoretical possibility of a 3dB improvement. That is, twice the signal power is delivered to the TV compared to what a single antenna would do. In practice, 2.5dB is readily achieved, as 0.5dB is typically lost in the combining mechanism. But if the two antennas are pointed in different directions (toward different stations), a 3.5dB penalty for each antenna is the likely result.

Further, these statements remain true regardless of whether the antennas have shared or separate amplifiers. For a shared amplifier, if the antennas point in different directions, half the power each antenna takes in reflects off the combiner and is rebroadcast out the antennas.

For dual amplifiers, when the antennas are pointed the same way, this signal is increased by 6dB, but the noise is increased by 3dB, so the overall improvement is still 3dB. When the antennas are pointed in different directions (still talking about a dual-amplifier situation), the 3dB noise increase causes a signal/noise ratio loss of 3dB for both stations. Dual amplifiers can eliminate the combiner loss, but only if the amplifiers are closely gain-matched.

Ganging a pair of Channel Master 4228 8-Bay antennas gives you the best UHF antenna a consumer can achieve, with reasonable ease of installation.

Your only major decision is deciding between a side-by-side mount or a one-over-the-other mount.

Side-by-side mounting.

The elevation view of the radiation pattern, shown in Figure 9-19, is the same as for a single 4228 antenna.

Figure 9-19. Elevation view of side-by-side mounting

In the view from overhead (see Figure 9-20), the 16-bay antenna is 2.1 times more directional.

Figure 9-20. Aerial view of side-by-side mounting

This configuration can be good or bad; there is no better antenna than this setup for eliminating ghosts that arrive from near the front. However, if your antenna is going to have to rotate, the Channel Master rotor will have a hard time nailing a specific direction, at least when it has to move to that direction from another.

Hopefully, all your transmitting antennas are in the same direction, either because they are on the same tower or because the city sending the signal is so far away.

Tip

This is precisely why this antenna is ideal for picking up channels from a neighboring city; direction issues go away.

When a rotor is required, the one-over-the-other mount is usually wiser.

One-over-the-other mounting.

In most situations, a one-over-the-other is the wiser choice for a 16-bay mounting. The radiation pattern viewed from above (see Figure 9-21) is the same as for a single 4228.

But in the elevation view, the 16-bay is 2.2 times more directional (as shown in Figure 9-22). This is enough to require taking the horizon elevation into account; the antenna should be tilted up to point at the horizon, and perhaps 1 degree higher.

Figure 9-21. Aerial view of one-over-the-other mounting

Figure 9-22. Elevation view of one-over-the-other mounting

Tip

Some authors and installers will recommend that a motorized tilter be used because the angle of the incoming signal can change from day to day, and the angle does change. However, high-angle days are strong-signal days, and the loss of a dB won’t matter in those situations. I recommend a tilter only when a rotor must point the antenna in different directions with different horizon angles.

The simplest mounting technique requires a single heavy angle iron, 65 to 70 inches long. Attaching it just below its midpoint to the top of the mast will keep the assembly from being too front-heavy.

At 15 pounds, the 4228 is a heavy antenna. Putting up two of them requires a 1 1/2-inch, 16-gauge metal mast.

The total weight of the antennas, mast, mounting irons, etc., will exceed 40 pounds. Trying to erect this beast by yourself, especially on a sloped roof, is something akin to suicide, even without wind. You need help; you need a large helping of good judgment; and you need a rope around your waist so that you don’t fall off the roof when the whole thing tips over. Some antenna adjustments will likely be necessary too, so don’t think you can put it up once and be done with it.

The good news is that there really aren’t any special tricks to the setup. Mount the mast, and then mount the antennas on the mast with the supplied antenna hardware. Figure 9-23 shows a side view, and Figure 9-24 is a front view, of two antennas in a one-over-the-other mounting pattern.

The two antennas must be phase-matched. This means that the two signals must arrive at the combiner in phase.

You achieve this phase matching by maintaining symmetry in the feed system. In other words, the wires for each antenna should be identical in type and length, although the actual length is not critical. You could have two 10-foot cables, or two 50-foot cables; just make sure both cables are of the same length.

If a ground reflection causes one antenna to be phased ahead of the other, you should adjust this out by repositioning one antenna. The easiest way to do this is by finding a new horizon tilt angle. Simply adjust the tilt while watching the signal strength. Different stations could require different angles, but that is rare.

Figure 9-23. Mounted, ganged antennas

There is also a chance that you will mix up the polarities such that the two antennas subtract instead of add signal. This will result in two forward lobes, reduced in size, with a null straight out the front (see Figure 9-25). After the antenna is fully hooked up, you should rotate the antenna to check for this pattern. If this appears to be occurring, reverse the connections on one of the antennas. The antennas come with a balun that has a “China” stamp on one side. I believe this stamp is the key to getting addition on the first try; just make sure connections are identical on both antennas.

My neighborhood has hot spots and cold spots—places where the signal strength is particularly strong or particularly weak. This is a consequence of overlapping fields. Because I’m 40 miles from San Francisco and behind some hills, DTV reception is possible only when my antenna is positioned in a hot spot. These hot spots are 10 to 16 feet apart for any channel, and are in different places for different channels. If you have hot spots for any one UHF channel, you will have hot spots for all UHF channels (in the same direction). The distance between hot spots is determined by the frequency, the distance to the horizon, and the geometry of the ridgeline at the horizon. In fact, it’s that ridgeline that is producing the overlapping fields.

Figure 9-24. Front view of ganged antennas

Figure 9-25. Phasing (correct and incorrect) in ganged antennas

If one 4228 is in a stronger field, part of its signal will be retransmitted out of the weaker antenna. This loss can equal the little bit of gain you had hoped to gain from the weaker antenna. In these cases, you likely will find that two 4228s are no better than one. This retransmission is avoided only when both 4228s are in equal fields.

At my house, the change in field strength in just 3 feet is enough to wipe out most of the hoped-for 3dB gain when the antennas are mounted side by side. Fortunately, hot spots are not generally spherical. Rather, they tend to extend upward and forward more than they extend laterally. So, the one-over-the-other configuration is much more likely to work in a neighborhood with hot spots.

But, of course, there is an exception to that general rule. If the 16-bay antenna is close to the ground, and the ground is bare extending toward the desired station, an efficient ground reflection is likely. This is another case of overlapping fields. But in this case, the hot spots are mainly arrayed vertically; they are likely close together vertically, but farther apart laterally. In this situation, the side by side is the configuration more likely to work. The incoming wave is angled downward by only a couple of degrees, and so the ground reflection occurs on ground that extends perhaps hundreds of feet toward the station. If this ground is paved, dirt, water, or a grass lawn, the reflection is efficient and will produce extremely weak cold spots. If it is covered with weeds, shrubbery, trees, or somebody’s house, the reflection is scattered too randomly to have any effect on UHF reception.

If you want to explore the locations of your hot spots, a Silver Sensor antenna on a 10-foot pole is a good method. This antenna is small enough to fit in any hot spot, and probably strong enough for a digital-lock in a hot spot for your strongest station. If possible, work at about the elevation where you plan your permanent antenna to be mounted. You will need a monitor positioned there so that you can see the signal strength from the receiver. The distance between the hot spots will be roughly the same for all channels.

If your hot spots are too small both vertically and laterally, a 16-bay might be out of the question. Your option, then, is to put each 4228 in its own hot spot. But this works for only one channel.

You might curse your bad luck if you find you have hot and cold spots, but you would be looking at it wrong. In fact, your neighborhood is concentrating the signal for you. An antenna in a hot spot can be at least 3dB smaller than it would need to be in a “flat” neighborhood. Now, if only the hot spots never moved. But, that is another story...

—Kenneth L. Nist

There are three types of grounds. In order of difficulty to achieve, they are (from most difficult to least difficult):

The methods and practices used to achieve each of these are different. Static grounding is the most difficult to do with guaranteed results, while electrical grounding is easy and can be considered to work perfectly in most cases. RF and electrical grounding are not important for static discharge (lightning) safety, so I’ve left them out with regard to outdoor antennas.

The general rule on outside antennas is that they need to be grounded. There is literally no known government agency that recommends antennas not be grounded for safety. Indeed, many local and city codes require grounding.

The probability of direct and secondary static electricity (lightning) strikes increases with the buildup of static charge at points of conductivity, and of course the metal mast or pole of an outdoor antenna is perfect for doing just that. Static electricity is built up during a thunderstorm as wind blows over the metal structures. This static charge builds and becomes an attractor to the opposite charge of static buildup in the storm clouds. By draining off the static charge continuously, via a ground, you reduce the probability of strike because the potential difference of charge is reduced.

Studies conducted on the Empire State Building showed that the probability of a strike was in direct relation to the quantity of static buildup on conductive structures. Conductive structures with no ground path were at the highest risk, while structures that were intensely grounded over several contact points were at the lowest risk.

On an antenna, you can ground the mast, the boom, the dish, and the director and reflectors of the antenna by contact metal bonding to a ground wire. Then run that wire directly into the earth via a deep ground rod. However, you cannot directly ground the driven element or active element of the antenna. All you can do is make a reasonable attempt at grounding it via a special coax grounding block to reduce static charge buildup and reduce probability of a hit. This block is a device designed to bleed off high-voltage spikes that reach dangerous levels, keeping them from damaging your receiving equipment. The block doesn’t directly short out the center conductor to the ground because this would kill the signal, but rather, allows a small gap that will—on a continuous basis—bleed off the building static charge before it reaches dangerous and damaging levels. Using one of these grounding blocks located just before the coax feed wire enters your building is what is recommended to effectively reduce the probability of small static electricity damage to your receiver. Still, a grounding block won’t protect against a direct lightning hit. Additionally, both the grounding block on the coax and a direct ground wire to the mast of the antenna should be used.

In a simple static charge buildup, the minor hits can be silent killers. These tiny hits will be damaging to your receivers’ RF frontend. It will most likely short out sensitive diodes in the receivers, rendering them useless. In the next worse case, you take a secondary hit; this usually occurs when the direct hit struck a tree or utility pole nearby. In this case, you might see some signs of obvious visible damage, such as the wiring in your house catching on fire, or your TV set getting fried right before your eyes. This happens far less often than the hidden damage hit. Finally, there is the rarest type of hit, which is a direct lightning bolt strike to your antenna or house. This usually will cause major fire damage to your dwelling and contents. Fortunately, these hits are rare except in places such as open farmlands where the house structure is the only corona point sticking up out of the flat ground for miles around. These structures serve as a big static attractor to a thundercloud. In areas where you are surrounded by trees and other structures, your odds of a direct hit are greatly reduced, but you are still at risk for the secondary hit and the silent static killer.

With all this in mind, realize that grounding will not protect you if you take a direct, or even a secondary, hit. What grounding does do is reduce the probability of getting hit in the first place; it also provides much better protection against the damage caused by silent hits. Because this is the most common type of hit, that’s a real advantage to have in your system. The idea of the grounding is to reduce the probability of getting hit in the first place, and to continuously bleed off small static charges to prevent the silent killer to your equipment.

—Keohi HDTV

Realize first that lens flare, and almost all artifacts that are generated within your set, result from light bouncing around and reflecting and refracting where it ought not. Since the basis of your picture is light, reflected off of a mirror, this might seem impossible to correct. However, you can work on eliminating light from reflecting and getting back into the lens system. In other words, you just want to allow light from the lenses, to the mirror, and onto the screen. Anywhere else and light within the TV is your enemy.

Figure 9-26 shows the end result of what we’re going for. This will sit in your TV around the lenses and ensure that no light from the lenses goes anywhere but straight to the mirror. The building process isn’t always clear as to what the final product is, so you may want to refer back to this figure as you go along.

Figure 9-26. Completed lens hood

First, you need to build a mockup. You can experiment with measurements, make design changes, and perform other spur-of-the-moment adjustments without worrying about screwing up expensive material or throwing away several hours of work. Start with some corrugated cardboard; I prefer white because it is easy to see in the darkness of your RPTV’s innards. You’ll need five different pieces; I’ll note my measurements, which are tailored to my Toshiba TW56X81. You can probably start with similar measurements, and work from there:

Figure 9-27 shows these pieces, laid out nicely and cut to dimension.

Figure 9-27. Individual pieces of the lens hood

It’s pretty easy to then put these together. Rather than bore you with a page of instructions, I’ll let Figure 9-28 do the talking.

Figure 9-28. Assembled lens hood mockup

Notice how Piece 3, on both sides, protrudes beyond the hole. You may want to draw some angled lines to make sure you get it lined up, and Piece 2 is correctly attached. Figure 9-29 shows Piece 3 with angled lines drawn in.

Sit this into your TV, and see how it works.

Now, you should make any needed corrections. If the base is too big, if the hole for the lens assembly is too small, or if the sides are too wide, you can make adjustments (it’s just a mockup, after all!). I had to cut arcs in the sides to avoid part of my lens being blocked. This is exactly why you mockup before working with the better material.

Figure 9-29. Piece 3 with angle lines drawn in

Once you’ve got things figured out, reconstruct the entire hood, using natural colored cardboard. Then, cover this with black Duvetyne fabric. I used 3M 77 spray adhesive to permanently fix the Duvetyne to the hood assembly.

Once you’ve got your hood, place it inside your TV, close up, and enjoy the results. I noticed a real improvement: my contrast increased, and “halos” around bright objects against dark backgrounds was dramatically lessened. And, all without voiding my warranty!

—Tim Procuniar