Kenwood TH78E - Manual (Page 34)

CTCSS OPERATION
The CTCSS unit (TSU-7) is included only with
models delivered to the United States and Canada.
The CTCSS unit (TSU-7) installation instruction are
shown on page 63.
If the Continuous Tone Code Squelch System
(CTCSS) function is activated, the transceiver will
not open squelch until it receives the proper PL tone
(tone squelch).
Selecting Tone Frequencies
You can select the desired tone frequency according
to the procedure on page 31.
The desired band will now operate in the Tone
Squelch mode. That is, squelch will not open until
the selected tone is received as a portion of the
incoming signal.
If you want to set the CTCSS function to another
band, repeat steps 1 and 2.
In duplex operation if CTCSS is activated in the
Sub and Main bands it is not active during
Operating the CTCSS Function
1 Press the BAND key to select the desired band.
2 Press the F key, then press the 3 key. The CT
indicator will appear on the display.