Maas AHT-28-V User Manual page 64

This transceiver has 8 groups' 5-Tone encoder and decoder to support the different
channels, the operation of calling/transmitting 5-Tone are as follows:
1) Select the channel with 5-tone signal.
(LCD displays "5T" at the right bottom of radio)
2) Press [ ], LCD displays "------"
3) Input the 5-Tone ID of radio you want to call
e.g.: input A-2-3-5-B in Group 2 in sequence, at this time the
keys [
and "D", so if you want to input A-2-3-5-B, press [
[ ], [
4) Press PTT to transmit
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], [ ], [ ], [
], [ ] [ ], in sequence
] stand for "A", "B", "C",
],