HDTV Antennas and Reception Systems

DTV HDTV Antennas and Reception:

You can get a good idea of the antenna system you need in your area by talking to several neighbors that you know have good TV reception. Make sure you have actually seen the picture on their TV.


Channels 2-83, up to 20 miles	Channels 2-83, up to 30 miles	Channels 2-83, up to 40 miles	Channels 2-83, up to 60 miles The top antenna is a 7' UHF dish

HDTV Channels 7-69 up to 20 miles	HDTV Channels 14-83 up to 50 miles Channels 7-13 up to 25 miles	HDTV Channels 7-69 up to 30 miles	HDTV Channels 7-69 up to 50 miles

Many Americans are finding out that they are being cheated out of between 20 to 60 or more television channels, because Cable and Satellite companies typically only give their customers a handful of the available local Digital Channels. These Digital Channels can provide four additional digital TV channels, in addition to the main HD Channel.

Many people now realize that cable and satellite companies typically charge an extra fee to receive this handful of main HD channels, and these channels are being counted in the company's "HD Package."

These companies sometimes give their customers reduced quality, and frequently "clip" (cut into local and network) programming with commercials inserted by Comcast, Dish, Directv, and others. Because of this, plus cable and satellite outages, people are turning to the high quality signals that they can obtain without having to pay a monthly fee.

History of Television (short version)

Television transmission in the 1920s was made by two short wave transmitters: one for sound, and one for the picture, which was made up of 30 lines.

Television transmission in the 1940s was made by two high frequency (HF) transmitters or two very high frequency (VHF) transmitters: one for sound, and one for the picture, which was made up of 525 lines in the U.S.

Television transmission (terrestrial) in 2009 was made by two VHF or two UHF transmitters: one for sound, and one for a digital picture, which was made up of either 480, 720, or 1080 lines, or a 525 line NTSC analog picture, consisting of picture brightness levels, and subcarriers for color information.

Customer's rules for arranging a television service call or antenna installation:

MAKE SURE IN ADVANCE THAT ANY TECHNICIAN COMING TO YOUR HOME HAS THE NECESSARY EQUIPMENT TO MEASURE SIGNAL STRENGTH and SIGNAL QUALITY LEVELS. DON'T LET YOURSELF BE CHARGED A SERVICE CALL FOR SOMEONE WHO IS JUST "GUESSING."

See rule #1

Here are a few of the questions you must know, or do a little research if you don't. Most of the answers will be discussed in the sections below:

Antenna types and selection: What do I need for my location?

Things I need to know: Is my antenna designed for 300 ohms or 75 ohms?

Things I need to know: Does my new HDTV antenna only receive channels 7 to 69? Do I need an antenna that also receives channels 2 through 6, or the FM radio band from a distant city?

Antenna signal amplifiers and installation: Will it help or hurt?

Antenna Rotors: Do I need one?

>>> You can get a good idea of the antenna system you need in your area by talking to neighbors that you know have good tv reception. Make sure you have actually seen the picture on their TV.

DTV Antennas and installation

You can't always bring home an HDTV set and use your old TV Antenna. Here is the key: If you have a "ghost" or "smear" to the right on an analog TV channel coming from the same direction as the Digital Signal you're trying to pick up, you're antenna system will virtually always need to be upgraded or replaced. And who is writing this article? I am the former Assistant Chief Engineer and Transmitter Supervisor of the old Channel 4 CBS affiliate in Miami Florida, WTVJ (now WFOR).

This first part is an ideal HDTV antenna installation:

Install a separate OUTSIDE antenna for your HDTV set for local TV reception. Outside antennas provide a direct link to the television station, and give you the highest quality for local channels.

A DIRECTIONAL ANTENNA usually provides the best reception. Directional antennas help eliminate multipath that cause break-ups (picture "freezes" or "pixelates") on digital channels, and ghosts or smearing appears on analog channels. Directional antennas have higher gain (captures more signal) which helps make up for many DTV Stations operating at low power.

Your objective is to pick up the signal coming directly from the transmitting tower, without picking up signals bouncing off of buildings, metal roofs, etc. The directional goals of a "Suburban" or "Fringe" antenna is to reject signals coming from any direction other than straight ahead. This is what you want in many cities,, even though you may have to use an attenuator to reduce the high signal levels from this type of antenna in urban environments. Mount your antenna away from all reflective surfaces or other antennas, and as high as practical.

It is extremely important to mount an outside antenna on a pole that goes all the way down to the ground, rather than mounting your antenna on the roof or chimney of your house. The reason for this will be apparent the first time your antenna is struck by lightning, and you DON'T have to call the fire department.

You should avoid using an antenna amplifier in urban areas or if you live within 10 miles of a television or FM radio transmitting tower or antenna. The amplifier will amplify everything, including the nearest telephone cell site and local police and utility 2-way radio and trunking systems.

Why do we rate the antennas for less range than the catalogs? There is a considerable amount of signal that is lost in the antenna wire that goes between the antenna and the HDTV receiver, and this subtracts from the usable range of the antenna. The higher the channel number, the higher the loss in this wire. No more than 100 feet of antenna wire should be used in any antenna installation, unless an MATV (Master TV) Amplifier is used.

CAN I PUT UP A TV ANTENNA WHEN MY LANDLORD OR HOMEOWNERS ASSOCIATION OR MY CITY SAYS I CAN'T?

Yes you can, and the U.S. Government guarantees it in writing. IT'S THE LAW:

The Federal Communications Commission guarantees you the right to install a TV antenna, even if local zoning codes or "Condo Associations" forbid it, << CLICK HERE. >>

ANTENNA ROTORS - DO I NEED ONE FOR HDTV?

Buy an antenna rotator for your antenna if the stations you are trying to receive are more than 70 degrees apart. If you live less than 5 miles from an HDTV station, you may have to buy a 10 or 20 db "attenuator" to reduce the signal to a level that will not overload your HDTV set. This is the equivalent of you putting on sunglasses on a bright day. Too strong a signal can overwhelm (overload) your HDTV tuner, DVR, or other device.

TROUBLESHOOTING an HDTV antenna system:

If you are located far from the TV transmitter and have an airport or an aircraft flight path or an occasional airplane between you and the TV transmitter, you may experience momentary pixelation or interruptions in your Digital Television reception. This commonly happens when the digital signal bounces off an aircraft between you and the transmitter. Now you have multiple paths, referred to as multipath. This "bounced" signal from the aircraft can occasionally cancel out the signal coming directly to you from the transmitter.

One of the most common causes of poor HDTV reception is an AMPLIFIER in an antenna system. Strong signals from Cell Towers, FM Radio stations, TV stations, and even 900 MHz telephone systems cause the amplifier to distort Digital Television (DTV) signals. These amplifiers don't just amplify the channel you're watching, they amplify EVERYTHING. An FM TRAP (filter that removes FM stations) is sometimes necessary. All these signals can overwhelm an HDTV receiver, just like a camera's flash "blinds" your eyes. Too high a signal is just as bad as too little. Remember: your antenna delivers ALL TV, FM, cellular, and 2-way radio stations to your HDTV tuner at the same time.

Use an antenna mounted amplifier with an antenna ONLY if you live out in the middle of nowhere, a.k.a. "DEEP Fringe." You should be at least 30 miles or more from an HDTV station before even thinking of using an amplifier in your system. Make sure your amplifier has an FM TRAP, and be sure to turn the trap ON. DON'T place your amplifier at the TV. Place it at the antenna, and feed only one HDTV set for best results.

In some cases, it is necessary to use your antenna to "null out" strong signals, before you can receive a weak one. This type of installation requires a selective signal strength meter or a spectrum analyzer or display. This will allow you to visually null the strong signal, while ensuring that there is still enough signal on the weak channel. This is a common occurrence when you are trying to receive a weak channel from a distant city, when you have a strong local channel nearby. It is difficult to find a qualified technician to do this, and the equipment can run thousands of dollars.

MAKE SURE IN ADVANCE THAT ANY TECHNICIAN COMING TO YOUR HOUSE HAS THE NECESSARY EQUIPMENT TO MEASURE SIGNAL STRENGTH AND SIGNAL QUALITY LEVELS. DON'T LET YOURSELF BE CHARGED A SERVICE CALL FOR SOMEONE WHO IS JUST "GUESSING."

Seal all outdoor connections, especially at the antenna, with a product called "coax seal." If none is available, use RTV.   Humidity in the atmosphere is your worst enemy, and can form water droplets and corrode your connections.

Read this next section if you need to feed more than one TV from the same antenna.

If you have multiple TV's, and cannot put up separate HDTV antennas:

IF ALL THE TRANSMITTING TV STATIONS ARE IN THE SAME DIRECTION, and you have more than 2 TV sets, consider replacing the splitter with a high quality MATV (Master Antenna TV) Antenna Amplifier, with multiple outlets - one for each TV. Buy and install a termination for any output you don't use on the MATV amplifier. Place this MATV amplifier as close to the antenna as possible, under an overhang, or in the attic, and run a separate cable to each Television or FM receiver .

The purpose of this MATV amplifier is NOT to provide as much signal as possible to your HDTV set. TOO HIGH A SIGNAL WILL MAKE YOUR HDTV SET USELESS (pixelate). The purpose of this amplifier is to provide ISOLATION from each of the other TV sets and their cable runs.

Sec 1: How to Receive Distant HDTV Channels

Sec 2: How to Receive Suburban and Urban HDTV Channels click here

Note: The antennas shown below are for example only. We do not endorse or receive any money from the sale of these items. We serve the Broadcast Industry, and these products are provided as examples only.

Section 1: How to Receive Fringe and Deep Fringe Analog and HDTV Channels (HDTV Channels Greater Than 35 Miles) click here for antennas that can withstand high winds and ice

Things to consider:

The best method for receiving distant channels is to use separate UHF and VHF antennas. Only use a mast-mounted amplifier if you have a coax line longer than 75 feet between the antenna and your receiver, AND the stations are more than 30 miles away. Antenna pre-amplifiers do NOT make up for a smaller antenna. The TV antenna is like a lens on a telescope. If you increase the size of the antenna, weak signals appear clearer.

An HDTV antenna should be thought of as a spotlight in reverse; it should pick up a signal from only ONE direction, and reject all other incoming angles of the same signal (reflections) bouncing off of buildings, towers, et. This bouncing is known in RF terms as multipath, and shows up as a "ghost" or "smear" to the right of an analog TV picture. With a digital TV signal, this multipath can result in picture break-up or no picture at all.

Don't try to "split the difference" when pointing your antenna between two distant digital stations coming from different directions. If they're more than 30 miles away and more than 30 degrees apart, use a rotor and high directivity antennas, such as an 8-bay bow tie antenna for channels 14 to 70. NOTE: This antenna will also work fairly well on local (but not fringe) channels 7 through 13:

http://www.warrenelectronics.com/antennas/4228.htm This antenna provides the highest capture area, diversity, UHF gain, bandwidth, and directivity. When mounted at a height of 30 feet or more above ground, and with no obstructions between your antenna and the TV station, you should be able to receive full-power stations up to 50 or more miles away. If you are 20 miles or more away from the nearest UHF TV, paging, or 2-way radio transmitter, use this mast-mounted amplifier to make up for the signal lost in the line going to your TV set:

http://www.warrenelectronics.com/antennas/0264DSB.htm This antenna amplifier has separate UHF and VHF antenna inputs for separate antennas. It then combines and amplifies the signals, and sends them down a single cable to your TV.

--- OR ---

http://www.warrenelectronics.com/antennas/mxu59.htm This antenna provides high UHF gain, moderate bandwidth, and very good directivity. When mounted at a height of 30 feet or more above ground, and with no obstructions between your antenna and the TV station, you should be able to receive full-power stations up to 50 or more miles away. If you are 20 miles or more from the nearest UHF TV, paging, or 2-way radio transmitter, use this mast-mounted amplifier to make up for signal losses in the line going to your TV set:

http://www.warrenelectronics.com/antennas/0264DSB.htm This antenna amplifier has separate UHF and VHF antenna inputs for separate antennas. It then combines and amplifies the signals, and sends them down a single cable to your TV.

--- PLUS ---

Use a high directivity antennas for digital channels 7 to 13, AND YOU DO NOT NEED TO RECEIVE CHANNELS 2 TO 6:

http://www.warrenelectronics.com/antennas/y10713.htm This antenna provides high gain, moderate bandwidth, and good directivity for receiving channels 7 through 13. The mast-mounted preamplifier listed above has a separate input for this VHF antenna. Their is no need to buy two separate mast-mounted amplifiers. Use with one of the UHF antennas above for TV coverage.

--- OR ---

Use a high directivity antenna that covers ALL VHF channels (2 through 13), plus FM, for VHF TV stations more than 40 miles away:

http://www.wade-antenna.com/Wade/VHFFM.htm MODEL VIP-307SR
This monster from JERROLD (WADE ANTENNA) provides maximum long-distance reception for channels 2 through 13, and the FM Band. This antenna is not recommended for stations less than 25 miles away. When stations are more than 50 miles away, the antennas should be mounted on a tower at least 50 feet or more above average terrain. Towers or push-up poles that go all the way to the ground prevent roof damage from lightning strikes. Use with this VHF monster with one of the UHF antennas for full TV coverage.

--- OR ---

Use a high directivity antennas that covers ALL VHF channels (2 through 13), plus FM for VHF TV stations that are 20 to 40 miles away:

http://www.summitsource.com/antennacraft-cs900-fringe-area-vhf-fm-hd-tv-antenna-33-electronic-elements-directional-aerial-cs-series-outdoor-television-local-offair-digital-hdtv-signal-reception-blue-zone-part-cs900-p-6265.html This $49 antenna from ANTENNACRAFT provides good long-distance reception for channels 2 through 13, and the FM Band. This antenna is recommended for stations from 20 to 40 miles away. When stations are more than 40 miles away, the antennas should be mounted on a tower at least 50 feet above average terrain. Use with one of the UHF antennas above for full TV coverage.

http://www.summitsource.com/antenna-craft-extreme-deep-fringe-vhf-fm-antenna-cs1100-vhffm-hd-antennacraft-33-electronic-elements-directional-tv-radio-aerial-outdoor-television-local-offair-digital-hdtv-signal-reception-blue-zone-part-cs1100-p-7101.html    The $69 (VHF/FM antenna) CS1100 is the big brother:

NEW ! ! !

Combination DEEP FRINGE HDTV Antenna for Channels 7 through 69

The AntennaCraft Model HBU44 will fulfill about 90% of your long-range HDTV reception needs.

For DEEP FRINGE, far from everything, when you do NOT need to receive channels 2 through 6, try this new antenna from ANTENNACRAFT:

http://www.summitsource.com/antennacraft-hbu44-high-band-vhf-uhf-hdtv-antenna-terrestrial-digital-hd-ready-hbu44-outdoor-44-element-offair-local-high-definition-signal-television-aerial-blue-zone-part-hbu44-with-coax-cable-p-7745.html This $75 antenna has a "BLUE ZONE" color code rating (deep fringe), and can pull in stations up to about 40 miles when mounted 20 feet above ground, and beyond 60 miles when mounted 50 feet or more above ground, and clearing the average tree line. For greater distances, an amplifier is required, and the two antennas can be used (stacked) for even greater signal capture to reduce flutter (dropouts).

NEW FOR URBAN AND SUBURBAN HOUSEHOLDS ! ! !

Combination HDTV Antenna for Local Channels 7 through 69

The AntennaCraft Model HBU22 will fulfill about 90% of your Local HDTV reception needs.

For receiving HDTV signals from nearby cities up to about 30 miles, and you do NOT need to receive channels 2 through 6, try this new antenna from ANTENNACRAFT:

http://www.summitsource.com/antennacraft-hbu22-high-band-vhf-uhf-digital-ready-hdtv-antenna-hbu22-outdoor-22-element-offair-local-hd-high-definition-digital-signal-television-aerial-red-zone-part-hbu22-with-coax-cable-p-6427.html    This $29 antenna can pull in stations up to about 30 miles distant when mounted 20 feet above ground, and beyond 40 miles when mounted 50 feet or more above ground, and clearing the average tree line. For greater distances, use the model HBU44 antenna.

Section 2: How to Receive Suburban and Urban HDTV Channels 2 through 69 (This includes the FM Radio Band)

20 to 45 miles

Use a combination UHF/VHF antenna

http://www.warrenelectronics.com/antennas/3671.htm   This Channel Master Model 3671 has many elements for each band. These elements not only contribute to good gain, but more importantly provide a flatter frequency response for both digital and analog TV signals, resulting in cleaner analog pictures, and little or no break-up of HDTV transmissions. The higher gain and sharper directivity also help reject "flutter" and multipath caused by weather fronts, atmospheric "skip" conditions, and signal reflections from aircraft. The extra gain also helps overcome coaxial antenna line losses.

15 to 35 miles

Use a combination UHF/VHF antenna

http://www.warrenelectronics.com/antennas/3679.htm This Channel Master Model 3679 has many elements for each band. These elements not only contribute to good gain, but more importantly provide a flatter frequency response for both digital and analog TV signals, resulting in cleaner analog pictures, and little or no break-up of HDTV transmissions. The higher gain and sharper directivity also help reject "flutter" and multipath caused by weather fronts, atmospheric "skip" conditions, and signal reflections from aircraft. The extra gain also helps overcome coaxial antenna line losses.

10 to 25 miles

http://www.summitsource.com/channel-master-3677-ultrahi-crossfire-vhf-uhf-fm-hd-tv-antenna-cm3677-35-element-fringe-offair-local-signal-aerial-blue-zone-part-cm3677-with-coax-cable-p-6286.html   This antenna provides good response, directivity, and multipath rejection.

Up to 20 miles away

http://www.warrenelectronics.com/antennas/3016.htm For STRONG-SIGNAL reception up to 20 miles. AN ATTENUATOR MAY BE NEEDED IF A TRANSMITTER IS VERY CLOSE.

Up To 15 Miles,

Good HDTV Reception On Channels 7 - 69

http://www.warrenelectronics.com/antennas/2016.htm   For STRONG-SIGNAL line of sight reception up to 15 miles.

Up To 15 Miles,

Good HDTV Reception On Channels 14 - 69

WARNING: Fair Reception Channels 7 - 13

http://www.warrenelectronics.com/antennas/4220.htm    For STRONG-SIGNAL line of sight reception up to 15 miles.

When using separate antennas, DON'T MOUNT VHF ANTENNAS (channels 2-6) ON THE SAME MAST, unless they have a 10 foot or more vertical separation, and 6 foot or more vertical separation for channels 7-13).   UHF yagi-style antennas can usually be mounted with about a 4 foot vertical separation. If you are going to combine signals from antennas pointed within 90 degrees of each other, use a channel filter for each antenna on the same band, so as not to pick up out-of phase signals or multipath through the other antenna. Then and only then you may combine the signals through a combiner (a kind of "splitter" in reverse).

IF YOU LIVE CLOSE TO AN HDTV STATION, you may have to install an ATTENUATOR to REDUCE the strength of the signal to a level that is useable by your HDTV receiving equipment. This is the equivalent of wearing sunglasses in bright sunlight.

Do NOT use a 300 ohm antenna system without replacing the old 300 ohm twin lead. Twist the wire 2 to 3 turns per foot. This prevents the wire from picking up signals directly, which causes multipath and analog ghosting. A highly directional antenna, designed for a fully shielded coaxial cable, is preferred in today's houses, which have electrical devices that radiate interference.

If you insist on using a 300 ohm antenna, use a high quality "BALUN" to convert the 300 ohm impedance of the antenna to 72 ohms to match the impedance of the coaxial cable going to your TV set. Then use low-loss 72 ohm, 100% shielded coaxial line to the TV or PC Card.

If you MUST use 300 ohm line, TWIST it 2-3 turns per foot
to prevent it from picking up signals directly from the 300 ohm antenna wire (multipath).

AVOID USING AN ANTENNA WITH A BUILT-IN
PREAMP, unless you are far away from any transmitter,
including FM, 2-way radio, and especially cell towers.

YOU MUST TERMINATE ALL UNUSED RF AND VIDEO
coax lines from splitters and distribution amplifiers.
If you don't have a TV connected to a TV outlet jack in another room, install an RF Termination.
Failure to do so could cause the reflected signal to corrupt
the digital data stream, and may cause your signal to "freeze"
for no apparent reason, or with the slightest bit of
additional multipath or interference. Analog signals may have "ghosts" or a smear to the right side of the picture.

If you install a system near a Radio, FM, HAM, Cell Phone, or other tower, or other source of radiation, INCLUDING SOME MICROWAVE OVENS, use a TV-Bandpass Filter between your TV antenna and your TV receiver.

There are many potential causes of emissions (unwanted RF or interference) that might prevent you from receiving HDTV, or cause your HDTV picture to "FREEZE." Most can be detected by a portable AM RADIO, that is NOT tuned to any station, just static.   Listen for an INCREASE IN STATIC or "CLICKING" Noise as you go from room to room, or towards a suspected source. This is how I found RF interference coming from my SONY Weather Radio. Every time the green fluorescent light on the front panel flashed, a burst of RF (Radio Frequency(s)) was emitted. Other sources of Digital Television Interference include, but are not limited to:

Power distribution grids that emit "static," especially poles with lightning arrestor banks.

Power distribution grids that emit "static" caused by bad grounds.

Ignition "noise" from parked or passing cars, motorcycles, lawnmowers, et.

Portable home telephones, Cell Phones, and (digital) 2-way radio equipment

Starting circuits on motors, pumps, and air conditioners.

RF emissions from fax machines, computers, "screw-in" type florescent lamps with electronic ballasts, and even some battery charges for laptops, camcorders, et.

Home and industrial lighting dimmers

Appliances, including other TV's

Battery operated Tools (drills especially) and Toys

Common tube-type florescent lamps, especially towards the end of their life when they "flicker"

Christmas lights that blink

Recap of thing to consider:

An HDTV antenna should be thought of as a spotlight in reverse; it should pick up a signal from only ONE direction, and reject all other incoming angles of the same signal (reflections) bouncing off of buildings, towers, et. This bouncing is known in RF terms as multipath, and shows up as as a "ghost" or "smear" to the right of the image.

Don't try to "split the difference" when pointing your antenna between two digital stations coming from different directions. If they're more than 30 degrees apart, use a rotor, or separate antennas.

When using separate antennas, DON'T MOUNT VHF ANTENNAS (channels 2-6) ON THE SAME MAST, unless they have a 10 foot or more vertical separation, and 6 foot or more vertical separation for channels 7-13).   UHF yagi-style antennas can usually be mounted with about a 4 foot vertical separation. If you are going to combine signals so that you have only one lead going into your house, use a channel filter for each antenna, so as not to pick up out-of phase signals or multipath through the other antenna. Then and only then you may combine the signals through a combiner (a kind of "splitter" in reverse).

IF YOU LIVE CLOSE TO AN HDTV STATION, you may have to install an ATTENUATOR to REDUCE the strength of the signal to a level that is useable by your HDTV receiving equipment. This is the equivalent of wearing sunglasses in bright sunlight.

Do NOT use a 300 ohm antenna system. Replace it with a
Highly Directional Antenna System, designed for a fully
shielded, Coaxial Cable antenna lead to your receiver.

If you insist on using a 300 ohm antenna, use a "BALUN" to convert the 300 ohm impedance of the antenna to 72 ohms to match the impedance of the coaxial cable going to your TV set. Then use 72 ohm, 100% shielded coaxial line to the TV or PC Card.

If you MUST use 300 ohm line, TWIST it 2-3 turns per foot
to prevent it from picking up signals directly from the wire (multipath).

AVOID USING AN ANTENNA WITH A BUILT-IN
PREAMP, unless you are far away from any transmitter,
including FM, 2-way radio, and especially cell towers.

YOU MUST TERMINATE ALL UNUSED RF AND VIDEO
coax lines from splitters and distribution amplifiers.
If you don't have a TV connected to a TV outlet jack in another room, install an RF Termination.
Failure to do so could cause the reflected signal to corrupt
the data stream, and may cause your signal to "freeze"
for no apparent reason, or with the slightest bit of
additional multipath or interference.

If you install a system near a Radio, FM, HAM, Cell Phone, or other tower, or other source of radiation, INCLUDING SOME MICROWAVE OVENS, use a TV-Bandpass Filter between your TV antenna and your TV receiver.

There are many potential causes of emissions (unwanted RF or interference) that might prevent you from receiving HDTV, or cause your HDTV picture to "FREEZE." Most can be detected by a portable AM RADIO, that is NOT tuned to any station, just static.   Listen for an INCREASE IN STATIC or "CLICKING" Noise as you go from room to room, or towards a suspected source. This is how I found RF interference coming from my SONY Weather Radio. Every time the green fluorescent light on the front panel flashed, a burst of RF (Radio Frequency(s)) was emitted. Other sources of Digital Television Interference include, but are not limited to:

Power distribution grids that emit "static," especially poles with lightning arrestor banks.

Power distribution grids that emit "static" caused by bad grounds.

Ignition "noise" from parked or passing cars, motorcycles, lawnmowers, et.

Portable home telephones, Cell Phones, and (digital) 2-way radio equipment

Starting circuits on motors, pumps, and air conditioners.

RF emissions from fax machines, computers, "screw-in" type florescent lamps with electronic ballasts, and even some battery charges for laptops, camcorders, et.

Home and industrial lighting dimmers

Appliances, including other TV's

Battery operated Tools (drills especially) and Toys

Common tube-type florescent lamps, especially towards the end of their life when they "flicker"

IMPORTANT:
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