CTCSS What And Why

By Jonathan Imberi

This chart shows each PL tone's two-character alphanumeric designator and corresponding tone frequency in Hertz.

XZ

67.0

1B

107.2

6A

173.8

WZ

69.3

2Z

110.9

6B

179.9

XA

71.9

2A

114.8

7Z

186.2

WA

74.4

2B

118.8

7A

192.8

XB

77.0

3Z

123.0

M1

203.5

WB

79.7

3A

127.3

8Z

206.5

YZ

82.5

3B

131.8

M2

210.7

YA

85.4

4Z

136.5

M3

218.1

YB

88.5

4A

141.3

M4

225.7

ZZ

91.5

4B

146.2

9Z

229.1

ZA

94.8

5Z

151.4

M5

233.6

ZB

97.4

5A

156.7

M6

241.8

1Z

100.0

5B

162.2

M7

250.3

1A

103.5

6Z

167.9

0Z

254.1

About CTCSS

CTCSS stands for Continuous Tone Coded Squelch System, often referred to as "PL" for Private Line (Motorola's trade name). GE calls it Channel Guard. Many repeaters require the use of a PL tone to access the repeater.

Contrary to popular belief, many repeaters that require the use of a specific PL tone to access the repeater are NOT closed repeaters. PL is often used as a means of solving an interference problem, or preventing one in the first place. Some repeaters may also generate a PL tone on the repeater output so that repeater users who are equipped with a radio capable of decoding PL will not hear other interference sources on the channel that would otherwise open the user's radio's squelch.

We strongly recommend the use of PL on repeaters' receivers. PL is a minor inconvenience when you consider how many potential problems it can eliminate. The use of PL may be required for a coordination to be granted if conditions so warrant, such as proximity to a co-channel repeater, or in an area where band openings frequently aggravate co-channel interference problems.