- Automatic Band Control. This feature will automatically switch the
active band (the one with receive activity) to the main band position.
This feature is present on dual band radios.
- Automatic Limiting Control. This feature will automatically limit
(reduce) the output power of a transmitter. This feature will protect
the transmitter in the event of high SWR.
key command - This refers to the secondary function of a key. The
alternate or secondary function is selected by first pressing (and
sometimes holding) a [FUNCTION] key.
- This refers to a group of frequencies. Many of the "DUAL BAND"
radios can operate on two or more bands. The 2 meter band is the group
of frequencies between 144 MHz and 148 MHz. The 440 Band contains the
frequencies between 440 MHz and 450 MHz.
- Some radios store memories into memory banks. A 100 memory radio may
have the memories grouped into 10 banks with 10 memories in each bank.
Memory banks can be useful to help group "classes" of frequencies.
Fire, Police frequencies are often grouped into separate banks.
This refers to an audible sound that occurs signaling a specific
event, ie. Keyboard key pressed, Signal received or other event.
A bell symbol is often used on an L.C.D. display to show that the
"BELL ALERT" function is active. In Bell Alert mode, the speaker is
turned off and an audible bell sound will signal the reception of a
Tone "BURST" is a signaling mode used in Europe in place of the PL
(sub audible tone) we use in America. In tone burst mode, a tone or
group of tones is transmitted each time the P.T.T. key is pressed. The
receiving radio will only turn on the speaker when the proper "Tone
Burst" is received.
- When a signal is present on a frequency, the channel is "BUSY". The
"BUSY" light will light when a signal is present or when the squelch
is set too low to block out the background noise on a frequency.
Channel - This is a specific memory channel used to store your
favorite frequency. It is often selected with a single key.
A signal on a frequency. In the scan mode, carrier scan will stop the
scan whenever a signal is present.
This is the same feature as "REVERSE". Refer to Duplex or repeater
operation. It is often desirable to "CHECK" the repeater input
frequency. The [CHECK] key, while pressed, will monitor the input.
Many of the new radios have a clock feature. The presence of a clock
will also provide automatic power off and power saver functions.
- Continuous Tone- Coded Squelch System. Also the same as PL (private
line) or DECODE. CTCSS refers to a mode where the speaker is muted
unless a specific PL tone is present on the received frequency. A
radio can be set in three CTCSS modes: 1) Not using any form of CTCSS.
2) PL Encode only mode. This places a sub audible tone on the
transmitted signal only. 3) CTCSS Decode mode. The PL is encoded on
the transmitted signal and the speaker is muted unless the received
signal has the proper tone.
- See CTCSS. This is a term also used to describe DTMF and Tone Burst
The electronic component used to find a PL, DTMF or Tone Bursts. A
decoder is often an optional accessory.
Squelch - Digital Squelch operates in the same faction as CTCSS.
The squelch will remain closed until the specific digital (often DTMF
) tones are received. A digital Squelch is usually an optional
accessory for a radio.
-A button used to lower the illumination of the display screen.
Dual Tone Multi Frequency. A DTMF keypad is a standard accessory on
most modern radios. When a DTMF key is pressed along with the P.T.T.
key, a two tone sound is transmitted. A receiver with a DTMF decoder
can convert the tones back into an electronic command.
Two. Some radios can operate on two different bands. It is called a
dual band radio. Some radios have two VFO modes. It is called dual
- Transmission and reception on different frequencies. Repeater
operation requires simultaneous reception and transmission. When a
is in duplex mode, reception is on the displayed frequency and
transmission is offset from the receive frequency by a predetermined
amount and direction. On 2 meters the offset is set at 600 kHz. The
direction of the offset (up or down) is determined by local practice.
- To encode a tone (sub audible) on the transmitted signal. Often
called to as PL. See CTCSS.
- The objective of the key, lever or switch. The [FUNCTION] key is
often pressed to select an alternate key command.
- Cycle per second. Hz
- Hiding a memory may prevent it from being used in normal operation.
This feature will allow you to skip unused memories during scanning
- 1000 cycles per second kHz
Display - Liquid Crystal Display. This type of display requires
external lighting to see properly. LCD display consumes very little
power and are present on most modern radios.
- See Programmable Scan. Certain scan modes will allow you to select a
frequency range to scan. The lowest frequency is called the lower limit
and the highest frequency is called the upper limit. These limits are
often stored in two specific memory locations.
- A memory may be locked out from the memory scan mode. You may wish
to lockout a memory if it contains a busy repeater.
1 million cycles per second. MHz
- A memory can store a frequency, offset direction, PL tone and other
related items. Most modern radios have at least 10 memories. The
desired frequency, etc. is set up in the VFO mode and is then
transferred to a memory with a set of keyboard commands.
- To silent a speaker. A mute key is pressed to silence the speaker.
- see duplex and offset. It is sometimes useful to change the value of
the offset in Duplex mode. Storing an Odd-Split repeater means to
store in a memory channel a separate receive and transmit frequency.
Some radios allow you to enter the receive and transmit frequencies
directly into a memory channel. Other radios require you to enter the
receive frequency and the value of the offset.
- The value of the difference between the receive and the transmit
frequency in the Duplex mode. On 2 meters the offset is 600 kHz. The
direction of the offset (Up or down) is set by local convention. On
the frequency 147.00MHz. A positive (+) offset will transmit on
147.600 MHz. A down (-) offset will transmit on 146.400MHz.
- (Private line) Sub- audible tone. A PL tone is encoded on a
transmission. A PL decoder (CTCSS) can identify the PL tone and act
accordingly. The are 38 suggested PL tones.
saver - Many of the newer radios have a feature called Power
saver. This feature will conserve power by entering a limited "off"
mode for a short duration and then quickly turn on for a few seconds
to check for channel activity. If no activity is found, the cycle
starts over. The period of "off" time conserves a great amount of
power. This assumes that the channel be monitored is not constantly
- Many radios have a Priority memory channel and a priority watch
feature. When the priority watch mode is active, the radio will
regularly jump to the Priority memory channel to check for activity.
If no activity is found, the radio will return to the last frequency.
band scan - Certain scan modes will allow you to select a
frequency range to scan. The lowest frequency is called the lower
limit and the highest frequency is called the upper limit. These
limits are often stored in two specific memory locations.
Push To Talk. This is the key used to cause the radio to transmit.
To restart with the default features, functions and data. Most modern
radios utilize a microprocessor. Resetting the microprocessor will
often clear all memory and VFO data.
- see Offset, Duplex and Check. The Reverse key will cause the
Transmit and receive frequencies to be exchanged. The radio will the
receive on the repeater input and transmit on the repeater output.
- The control that shifts the receiver up or down in frequency to
improve the reception. Most often used in 1.2 GHz equipment.
see Power Save
Time operated, Carrier operated - See Programmable band scan.
Scanning a frequency range of a memory bank can be performed in a
number of ways. You may wish to scan and stop on a busy frequency for
a time period and then continue scanning (Time operated), or until the
signal on the frequency stops (Carrier operated).
Busy, Clear - See Programmable band scan, Scan Time operated
Scanning a frequency range of a memory bank can be performed in a
number of ways. You may will to scan for a Busy channel or for a clear
- see Duplex, Offset.
Strength - The relative amount of RF signal received by the radio
antenna. Signal strength is measured in "S" units
- see Duplex. When operating in the Simplex mode, The radio will
receive and transmit on the same frequency.
- The control on a receiver that automatically quiets a receiver by
reducing its gain.
- The amount of increase in frequency when a radio's tuning dial is
increased or decreased. Common steps are 5, 10, 12.5, 15,20 and 25
Khz. Most modern radios allow you to change the amount of the
see Band, Dual. On a dual band radio, one band is selected as the
main band and the other is then called the Sub-Band.
- Standing wave ratio. see A.L.C. When a transmitter is connected to
an antenna, it is hoped that all the RF signal will be radiated from
the antenna. In practice, some of the RF energy is reflected back to
the transmitter. Reflected energy can damage the transmitter
components. The radio of the forward power and reflected power is the
audible tone - see P.L., Encoder, Decoder, CTCSS. Sub audible
means that it is a tone frequency that is too low, or too high to be
heard by the human ear - or is filtered out by the radio receiver so
that it is inaudible to the listener.
The tone is often transmitted on a radio frequency along with voice
- A Flip-Flop. To change states or functions alternately. Press to
turn on press again to turn off is an example of a toggle switch.
alert - see Beep. When a radio is placed in Tone Alert mode. A
beeping will sound when a signal is present on a frequency. This
feature may be used along with CTCSS.
squelch - see CTCSS, PL, Decoder. When a radio is placed in Tone
Squelch mode, the speaker will only sound when a signal is present and
that signal contains the proper PL tone.
Wheel - Some radios make use of Thumb wheel controls to select the
desired frequency. Each wheel has 10 positions numbered 0-9.
Step - see Step
- Unlock has two different meanings.