G90 ACC port to laptop/mobile headset jack, by FloppyFox
--------------------------------------------------------

                                                            Headset jack, I/O.
                                                     4 pole (TRRS) 3.5mm jack.
Xiegu G90 ACC port.                                 Use mica washer on base of
Mini DIN 8.                                             plug to prevent sleeve
Loop cable through                                    shorting to the grounded
type 43 toroid                                           body of the connected
several times.                                                         device.
 |                                                                          |
 V                                                                          V
+---                                                                      ---+
| AUX IN <-------------------------/\/\/\------+----------------< L (tip)    |
| Pin 3                             3.3k       |                             |
|                                              |         +------< R (ring 1) |
|                                              |         |                   |
|                                              /         /                   |
|                                              \ 120R    \ 120R              |
|                                              /         /                   |
|                                              |         |                   |
| GND -----------------------------------------+----+----+----- GND (ring 2) |
| Pin 7, sheild                                     |                        |
|                                                   |                        |
|                                                   /                        |
|                                                   \ 1.8k                   |
|                                                   /                        |
|                                                   |                        |
|                                                   |                        |
| AUX OUT >----------| |---------/\/\/\-------------+---------> MIC (sleeve) |
| Pin 4             0.1uF         33k                                     ---+
|                    25V
|                  C0G preferred, X7R will work
+---

The 120R and 1.8k resistors are needed for some devices to recognise that a
headset is connected.


G90 pin assignments
1	PTT I/O
2	Band voltage output
3	Audio into radio, line level
4	Audio out from radio, line level
5	ALC
6	N/C
7	GND
8	+8V

Mini DIN pins looking into the socket on the radio:
 8 7 6
5   4 3
  2 1

Mini DIN pins looking into the male plug end:
 6 7 8
3 4   5
  1 2

TRRS jack:
--|
  +-----+---+---+-\/\
  |     |   |   |    \
  |     |   |   |    /
  +-----+---+---+-/\/
--|
 Sleeve  R2  R1  Tip
    Mic  GND R   L