800 Trunked Radio System
800 MHz Maximum Signal Strength, Are You Getting It?
How you configure and use your 800 MHz TRS portable radio equipment will determine what transmitter signal strength you are sending from your equipment. By learning your equipment, then configuring and using it properly, will enhance your ability to effectively communicate when needed.
First lets learn a little information about your equipment as this is important for the rest of the information provided:
- MTS 2000: This portable provides 3 watts of output power.
- XTS-3000: This portable provides 5 watts of output power.
Site Transmitter Power: Site transmitters output 100 watts of power. That is 33.33 times what your portable outputs if an MTS 2000 or 20 times that for an XTS-3000. That is why you may be able to receive messages clearly and strongly, but are unable to reach someone from where you are at with your portable.
Stubby Antenna: This antenna has about 3 db less gain than the regular long antenna and is intended for use only on the Public Safety Microphone. You should never use this antenna on your radio because of the reduced antenna gain.
Public Safety Microphone (PSM): This is a special microphone offered as optional equipment for your portable radio. The Stubby Antenna should never be used except with this microphone and always attached to the microphone antenna port as shown before operating the radio.
Coiled Cord Microphone: This microphone is an optional use accessory for your portable radio also. It‚s main disadvantage is that the antenna used with this microphone remains on the radio normally worn on the belt. When the radio is worn on the belt, transmitted signals are attenuated.
Now let‚s look at some configurations and applications. These try to demonstrate the knowledge you gained by reading the above:
- Scenario one: You are using your 800 TRS handheld with the straight cord microphone. When using this configuration, your best transmit and receive signal strength is gained by using the long antenna screwed into the microphone head, with the microphone worn or used at shoulder height. The second best would be the same configuration, but with the stubby antenna. REMEMBER: You increase your transmit power 3 db using the longer antenna. Also remember that this is the only configuration that use of the Stubby Antenna is appropriate.
- Scenario Two: You are using your handheld without a microphone. In this configuration your best transmit and receive signal strength is available when using the long antenna. When you talk on the radio, you raise it close to your mouth. This brings the antenna to shoulder height. Use of the Stubby Antenna is discouraged because of its 3 db gain loss.
- Scenario Three: You are using a coiled wire microphone, with the antenna positioned at your waist on the radio. In this configuration, you have the best transmit signal strength using the long antenna on your radio. Don‚t forget you have a transmit signal loss due to the location of the radio at waist level. If in structures like the Mall or in underground tunnels, you may have to lift the radio from the belt to mouth level to be heard.
NOTE: Use of the stubby antenna with the coiled microphone is strongly discouraged because it compounds your signal loss in transmit power. You are already have a loss in transmit capability because the radio is located at waist level. When you use the Stubby Antenna, you add a 3 db gain loss to what loss you already have.
- Scenario Four: You are using the 800 TRS portable with the straight microphone cord, with either the long or stubby antenna on the radio at your waist. In this configuration, you have NO ANTENNA operating on your portable. When you install the Public Safety Microphone on your radio, the Radio Frequency path is switched from the radio‚s antenna port to the Public Safety Microphone antenna port. Operating your radio without an antenna on the PSM has three major affects: 1) effective signal strength is heavily attenuated, jeopardizing the ability to communicate under all but ideal conditions; 2) Most of the radio transmitter signal will be reflected back into the radio which can damage it and void the warranty; and 3) the uncovered PSM antenna port can deliver a very painful shock when transmitting.