Skip's 4x4
Skip's 4x4
2-way Radio Info
by Alan

This page combines some useful information about common 2-way radios, including CB, UHF and HF-Marine radios, detailing their frequencies, channels, and uses of those channels. It also contains the Phonetic Alphabet, Morse code, and some useful statistics relating to antenna tuning. 

Modes of transmission:

Mode Meaning General Usage & Comments
AM Amplitude Modulation Frequencies less than 30MHz. Lower quality audio. Includes normal radio stations (500KHz-1.6MHz), CB radio (27MHz) and most short wave stations (2MHz-30MHz) etc.
FM Frequency Modulation Frequencies above 30MHz. Higher quality audio. Includes normal FM radio stations (88MHz-108MHz), VHF police & aircraft (50MHz), VHF Amateur radio (144MHz), UHF CB (470MHz), UHF Amateur radio etc 
SSB Single side band (includes LSB & USB) Frequencies in the 2MHz-30MHz. Poor quality audio. Esed commonly for long-distance communications, including Short-wave and 27MHz CB.
LSB Lower side band As above.
USB Upper side band As above.
CW Continuous Wave (Morse code, On/Off) This does not support audio. Rather is is just a continuous tone, as in Morse code trasmissions.

OFFICIAL PHONETIC ALPHABET and Morse code:

The phonetic alphabet is commonly used to spell out letters, when communications are dificult to understand, as in long distance coms, or noisy environments. The Morse code is not used commercially any more, and was officially phased out in 1999, although it is sometimes still used by Amateur radio enthusiasts. And we all know that the SOS signal ( ... --- ... ) is still often reffered to.

A .-   Alpha
B -... Bravo
C -.-. Charlie
D -..  Delta
E .    Echo
F ..-. Foxtrot
G --.  Golf
H .... Hotel
I ..   India
J .--- Juliett
K -.-  Kilo
L .-.. Lima
M --   Mike

0 -----
1 .----
2 ..---
3 ...--
4 ....-

N -.   November
O ---  Oscar
P .--. Papa
Q --.- Quebec
R .-.  Romeo
S ...  Sierra
T -    Tango
U ..-  Uniform
V ...- Victor
W .--  Whiskey
X -..- X-ray
Y -.-- Yankee
Z --.. Zulu

5 .....
6 -....
7 --...
8 ---..
9 ----.

Guide to tuning 2-Way Radio Antenna:

Antenna's on 2-way radio's need to be tuned to the frequency that they will be operating on. Although most antenna's sold by retail stores are pre-tuned, this tuning is often out, and can be improved upon. The tuning can also vary depending upon the way the antenna is mounted, and what type of antenna base / spring you have. If the tuning is way out, you can risk damaging the transmitter circuit in the radio. Some common reasons for the tuning to be way out are; A) if you are using the wrong antenna, B) if the antenna has a bit broken off it, C) if the wire that wraps around the antenna is cut, D) if there is a loose wire or short circuit in the coax leading to the antenna. So it is a good idea to borrow an SWR Meter to check the ratio. SWR stands for Standing Wave Ratio, and is basically a measure of the efficiency of the antenna circuit. The following chart is a guide to interpreting the readings...


SWR

PERCENT POWER
INTO ANTENNA

COMMENTS

1:1

100% Perfect

1.05:1

99.93% Excellent

1.1:1

99.78% Excellent

1.2:1

99% Very Good

1.5:1

96% Good

2:1

88% Improve if possible

2.5:1

82% Improve if possible

3:1

75% Bad - risk damage to transmitter

HF 27MHz Citizen Band (AM CB) Frequency / Channel chart:

Freq.  Old Channel Usage
(MHz)  Ch#

26.965   -   1  AM
26.975   -   2  AM
26.985   -   3  AM
26.985   -   -
27.005   -   4  AM
27.015  (1)  5  AM
27.025  (2)  6  AM
27.035  (3)  7  AM
27.045   -   -
27.055  (4)  8  AM  ROAD CHANNEL / TRUCKERS
27.065  (5)  9  AM/SSB EMERGENCY (LEGAL)
27.075   -  10  AM
27.085  (6) 11  AM  CALLING (LEGAL)
27.095  (7)  -  AM
27.105  (8) 12  AM
27.115  (9) 13  AM
27.125 (10) 14  AM
27.135 (11) 15  SSB
27.145 - -
27.155 (12) 16  LSB  CALLING (LEGAL)
27.165 (13) 17  SSB
27.175 (14) 18  SSB
27.185 (15) 19  SSB
27.195 (16)  -  SSB
27.205 (17) 20  SSB
27.215   -  21  SSB
27.225 (18) 22  SSB
27.235   -  24  SSB  (This isn't a typing
27.245   -  25  SSB  error. Channel 23 is
27.255   -  23  SSB  out of sequence)
27.265   -  26  SSB
27.275   -  27  SSB
27.285   -  28  SSB
27.295   -  29  SSB
27.305   -  30  SSB
27.315   -  31  SSB
27.325   -  32  SSB
27.335   -  33  SSB
27.345   -  34  SSB
27.355   -  35  LSB  DX CALLING CHANNEL
27.365   -  36  SSB
27.375   -  37  SSB
27.385   -  38  SSB
27.395   -  39  SSB
27.405   -  40  SSB

27.620 COMMON WALKIE TALKIE CHANNEL

Uniden Grant XL 40 Channel AM/SSB CB radio

HF Marine Band (27MHz):

MHz Ch# Usage
27.680   Commercial organizations, Ship-shore / inter-ship
27.720   Professional fishermen, Ship-shore / inter-ship
27.820   Professional fishermen, Inter-ship
27.860 1 Secondary distress, Safety / weather info, Amateur organizations
27.880 2 Emergency channel, Priority distress
27.900 4 General, Ship-shore, Amateur organizations (Calling and working)
27.910 5 General, Ship-shore, Amateur organizations (Calling and working)
27.940 6 Club events, Ship-shore / inter-ship (Calling and working)
27.960   Amateur organizations, Inter-ship
27.980   Surf rescue

UHF 476MHz Citizen Band (UHF CB)

Freq. Channel Usage

476.425   1  FM  Repeater output
476.450   2  FM  Repeater output
476.475   3  FM  Repeater output
476.500   4  FM  Repeater output
476.525   5  FM  EMERGENCY
476.550   6  FM  Repeater output
476.575   7  FM  Repeater output
476.600   8  FM  Repeater output
476.625   9  FM
476.650  10  FM
476.675  11  FM  Calling
476.700  12  FM
476.725  13  FM
476.750  14  FM
476.775  15  FM
476.800  16  FM
476.825  17  FM
476.850  18  FM
476.875  19  FM
476.900  20  FM

Freq. Channel Usage

476.925  21  FM
476.950  22  FM
476.975  23  FM
477.000  24  FM
477.025  25  FM
477.050  26  FM
477.075  27  FM
477.100  28  FM
477.125  29  FM
477.150  30  FM
477.175  31  FM  Repeater input
477.200  32  FM  Repeater input
477.225  33  FM  Repeater input
477.250  34  FM  Repeater input
477.275  35  FM  Repeater input
477.300  36  FM  Repeater input
477.325  37  FM  Repeater input
477.350  38  FM  Repeater input
477.375  39  FM
477.400  40  FM  Road / Truckies
(c) Skip's 4x4 2001

Ten Codes for CB Radio

The "10" codes were used in the early days of CB radio, and had 2 primary functions. First, they offered an abbreviation to common messages, and secondly, they helped communications when the signals were week, because simple numbers were more easily understood. Although the "10" codes are not often necessary now-a-days with modern FM transceivers, it is still common for people to say "10 - 4" at the end of their sentences, which simply means, "yes" or "over". Here is a list of common Ten Codes...

"10" Code Meaning

10 - 1

Receiving poorly

10 - 2

Receiving well

10 - 3

Stop transmitting (Standby)

10 - 4

Message Received (Yes, ok, roger)

10 - 5

Relay message too ...

10 – 6

Busy at present (Please standby)

10 - 7

Out of service, off the air

10 - 8

In service, on the air

10 - 9

Repeat Message

10 - 10

Transmission completed, Standby

10 - 13

Advise Weather and road conditions

10 - 20

My Location is ...

10 - 27

I am Moving to channel ...

10 - 30

Illegal use of radio

10 - 33

Emergency traffic on the channel

10 - 34

Request for assistance

10 - 36

Correct time

10 - 46

Assist motorist

10 - 77

Negative contact

10 - 99 Mission completed, all units secure

10 - 100

Rest stop (toilet needed) [number 1's; minor]

10 - 200 Official meaning: Police needed at ...
Common meaning: Toilet needed [number 2's; major]

For more complete lists of 10 codes, visit either of these sites...
http://home.att.net/~wizardoz/cbmw/10codes.html 
http://www.roity.com/rc/cbradio/cbcodes.html

Send me some feedback about these pages, by emailing me.

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This page was last updated on 15 Apr  2004