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G8MNY  > TECH     13.02.25 18:33l 64 Lines 2950 Bytes #0 (0) @ WW
BID : 25779_GB7CIP
Subj: Yaesu DTMF Mic YM-48
Path: JH4XSY<N3HYM<K5DAT<GB7BED<GB7COW<GB7CIP
Sent: 250213/0928Z @:GB7CIP.#32.GBR.EURO #:25779 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To  : TECH@WW

By G8MNY                                 (Revamp Nov 08)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)

I use mine with FT790/690/290 for DTMF control of a repeaters etc.

This is the diagram of the mic, I reverse engineered it ...

 >+5v rd
                       4x 1n                    47u===  ===220u    pin 4
  Keyboard         ))Ĵ
   Matrix  rd     === === === ===                         ___ UP ye/bn
  123A)))Ĵ                         o o>pin 6
             bn                                wh
  456B))Ĵ                             ___ DOWN bk/bl
             or                                  o o>pin 7
  789C)Ĵ          3.52                 
             ye              MHz                  ___ PTT bk
  *0#DĴ            ڴ[]ÿ              bno o>pin 3
  v  g  b  w                
  i  n  k  hĴ9 14 13  12 11  1 7 osc8  47            
         )Ĵ5  c  row  DTMF IC                     
      ))Ĵ4  o       8202  o/p          220u     
   )))Ĵ31 l 10    6     16        ĴĴ
  === === === === /    +        
   Ĵ      15K         2K2Ĵ              
      4x 1n          __                 \e     DTMF   
2K2                   / \e                  12RLSĴ
                       Ĵ                   rd    bk 
         u1          mute                               MIC wh
 Ĵ)))100R100R)>pin 2
                                                      
Mic ===  +                        Ĵ47K>3K3 DTMF    
    1n                         10K +1u        LEVEL     Screen
 >Pin 1

Here the UP & DOWN button are connected to earth, but they can be to +5V for
some rigs! So check your rig handbook to see which it needs.

DTMF SYSTEM
This uses two pure sine wave tones controlled from a 4x4 keypad matrix, a low-
frequency tone & a high-frequency tone, to specify 1 of the 16 options.

Pressing 2 keys in the same row/column, normal results in a single tone.

 TONE HIGH 1209Hz 1336Hz 1477Hz 1633Hz
  LOW
  697 Hz     1      2      3      A
  770 Hz     4      5      6      B
  852 Hz     7      8      9      C
  941 Hz     *      0      #      D

Frequency tolerance:         1.5%

The 2 tones must not clip & mix on the Tx/RF path/Rx as the DTMF Rx IC uses the
presence of more than 2 tones to identify the signal non DTMF & ignores it.


Why Don't U send an interesting bul?

73 de John G8MNY @ GB7CIP


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