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Tuning In: Frequencies and Reception Tips

Frequencies

San Francisco: 88.5FM
In the greater San Francisco Bay Area, tune in to KQED Public Radio at 88.5FM.

Sacramento: 89.3FM
In the greater Sacramento area, tune in to KQEI at 89.3FM.

Santa Rosa: 88.3FM
A translator allows the KQED Radio signal to reach Santa Rosa. In the Santa Rosa area, you can tune in at 88.3FM.

Martinez and Benicia: 88.1FM
A translator allows the KQED Radio signal to reach Martinez and Benicia. In the Martinez and Benicia areas, you can tune in at 88.1FM.

Reception Tips

Propagation
FM signals are like television signals. They do not go through hills. However, many different things manage to get the signals over and around hills so that you do not have to have a direct line-of-sight to an FM transmitter in order to receive its signal.

Weather conditions can affect how well the FM signal is propagated to you. If you live in a marginal receiving location, changes in weather can change your reception. The signal can change with time of day and time of year. In the Bay Area, typical weather conditions in September, October, and November bring the worst reception.

Most listeners are not affected by weather changes. When an FM signal gets up to a certain minimum strength, an increase does not cause any perceptible change. As long as the signal stays above this minimum value, the listener is not aware that the strength of the signal is changing.

Interference
A very strong, unwanted signal can cause a number of problems to FM reception. The strength of a radio signal is proportional to the inverse square of the distance to the transmitter. For example, the area around Sutro Tower will have much stronger signals from the Sutro Tower stations than from Mt. San Bruno, where the KQED-FM transmitter is located.

FM transmitters are scattered all over the Bay Area. To name just a few, FM transmitters are located on top of apartment houses in San Francisco, on Grizzly Peak in Berkeley, on Mt. Beacon above Sausalito, above downtown San Rafael, near Walnut Creek, as well as on Mts. Sutro and San Bruno.

Anyone who lives near one of these locations may have interference problems. Problems can also come from television transmitters and from non-broadcast transmitters, such as paging services and police, taxi, and tow truck dispatch points.

The strong signal overloads the radio receiver. Often, you can hear unwanted signals at several different places on the dial. However, a strong, unwanted signal can cause the wanted signal to be noisy in stereo, but quiet in mono, without causing any other symptoms.

Curing strong signal interference can be very difficult. You must determine that the problem is caused by a strong signal and is not multipath (see below). You may have to install an attenuator between your antenna and your receiver to reduce signal strength. Fixed attenuators for this purpose are available from radio supply stores. The attenuator reduces the amount of signal fed to the receiver. Older receivers are more vulnerable to this interference than most new ones. You may have to replace an old receiver with a new one.

Multipath
The FM radio signal is somewhat like light. It can be reflected by objects such as hillsides, buildings, automobiles, and by people. The FM receiving antenna picks up both a signal directly from the FM transmitter and simultaneously a number of reflected signals. These reflected signals may interfere with the direct signal. This condition is known as multipath reception.

An FM stereo signal is more vulnerable to multipath interference than is a mono signal. If a signal has a lot of hiss and noise in stereo but is quiet in mono, multipath is usually the cause. (Low signal strength or interference can cause similar symptoms.)

Because the wavelengths of different FM stations are not the same, the multipath situation is different for each individual FM station. Thus, one station can be quiet while the next one is noisy. The location of the receiver will also affect the amount of multipath interference. An area such as the San Francisco Financial district has a very strong KQED-FM signal present. However, all the reflections from buildings can make reception difficult.

A better quality antenna will minimize reception of unwanted reflected signals to reduce multipath interference.

Antennas
A good antenna is a must for good FM reception.

Basic Line Cord Antennas
Simple FM radios have built-in whip antennas or use the radio power cord as the antenna. Almost anything else is better. A line cord antenna consists of a clamp on the power cord, which is attached to one of the antenna screws on the back of the radio. The location of the power cord affects reception. Housecleaning often changes the position of a line cord antenna and thus the quality of reception.

Outdoor Antennas
A good outdoor antenna will provide the best reception. "Consumer Reports" magazine periodically rates FM outdoor antennas. A copy should be available at a good library.

In general, you want a directional antenna which receives signals from one direction only. DO NOT use an omni-directional antenna which receives signals from all directions. An antenna designed for FM only will be better than a combination FM-TV antenna.

If you already have an outdoor TV antenna, and prefer not to buy a separate one for your radio, try connecting it to your FM receiver. If you get good reception, you can install a signal splitter to connect the same antenna to both the FM radio and the television. A signal splitter is designed to connect one antenna to two or more receivers. Splitters are available at electronic parts stores such as Radio Shack. The salesclerk can advise you as to which type you need.

An outdoor antenna should be aimed for best reception. In most cases, best reception will occur with the antenna pointed at our KQED-FM transmitter on Mt. San Bruno. In some cases, best reception will occur with the antenna pointed in a different direction. Experimentation is the key.

Outdoor antennas deteriorate with age. Metals corrode. Wind can flex the lead-in until metal breaks. An outdoor antenna should be inspected for damage annually.

Indoor Antennas
No indoor antenna is as good as an outdoor antenna. However, landlords, deed restrictions, temporary housing, and other conditions may prevent your use of an outdoor antenna.

The simplest indoor antenna is the folded dipole. This antenna frequently is packed with new radios. It is fabricated from flat television antenna lead-in material (often called twin lead or ribbon lead). Twin lead is the flat plastic-covered wire - usually brown or white in color - used to connect a TV or FM antenna or receiver.

Replacing line cord antenna with a folded dipole antenna usually makes a big improvement. You can purchase an FM folded dipole antenna at Radio Shack or at a stereo store for under $3.00. Remove the line cord antenna from the antenna screw terminal on the back of the receiver. Connect the lugs of the folded dipole to the FM antenna terminals on the back of the radio. Usually two screws will be marked "FM Antenna" or "300 ohm FM" or some combination of these terms. See your radio instruction manual for more information.

A few radios, such as some Grundig models, require a special plug to connect an external FM antenna. See your radio dealer for this plug.

A folded dipole antenna is in the shape of the letter T. The horizontal part of the letter is the actual antenna. The vertical part of the letter connects the antenna to the receiver. Try orienting the top of the letter in different positions for best reception. It may give best results when it is vertical. Often, the antenna can be taped to the wall or to the back of furniture when a good location is found.

Better Indoor Antennas
A number of different manufacturers - such as Sony, Panasonic, and BIC - make better quality indoor antennas. Do not confuse these with TV rabbit ears antennas. Rabbit ears antennas are not as good for FM reception as is a folded dipole.

You may pay $80.00 or more for a good quality indoor FM antenna. Find a dealer who will let you try the antenna on a money-back agreement. The antenna may or may not work at your location.

Some indoor antennas have a built-in RF booster amplifier, which increases the strength of the signal before it goes to the receiver. The instruction sheet for the antenna will tell if it includes an amplifier. If you live in a remote area with no other radio stations for many miles, you may benefit from the booster amplifier.

If you are trying to receive a distant station in an area with local stations, the booster amplifier will probably cause more harm than good. The same principle applies to separate RF booster amplifiers used with outdoor antennas.

Coax or Twin Lead
Either coaxial cable or 300 ohm twin lead can be used to connect the FM antenna to your receiver. Both are good.

In general, I think you will get better results using coaxial cable with an outdoor antenna. Use RG-59 cable. A matching transformer, known as a balun, may have to be used on both ends of the cable. (Radio Shack part number 15-1140). See your antenna and receiver instruction manuals for more information. Connect coaxial cable only to the terminals marked "75 ohms." If the terminals are marked "300 ohms," a balun must be used between the cable and the terminals. The dealer who sells the antenna can advise you.

Cable

Comcast Digital Cable is the only Cable company carrying KQED, on Comcast Digital Cable Channel 960.

– Fred Krock, KQED Radio Chief Engineer (retired)

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