PMR radio for R124

Connection to R124

Connection in R124 A-1

Connection as R112.

Cont.		Cont.		Cont.
a1		b1	+26V Black	c1
a2		b2	Speaker Green	c2	GND Blue
a3	PTT Brown	b3	MIC- Orange	c3	MIC+ Red
a4		b4		c4
a5		b5		c5
a6		b6		c6
a7		b7		c7
a8		b8		c8
a9		b9		c9
a0		b0		c0

Connection as R123.

Cont.		Cont.		Cont.
a1		b1	+26V Black	c1
a2		b2		c2	GND Blue
a3		b3		c3
a4		b4		c4
a5		b5		c5
a6		b6		c6
a7		b7		c7
a8		b8		c8
a9		b9		c9	PTT Brown
a0	Speaker Green	b0	MIC+ Red	c0	MIC- Orange

M12 Connector

M12	Function	Wire color
1	+26V	Black
2	PTT	Brown
3	Mic+	Red
4	Mic-	Orange
5	NC	Yellow
6	Speaker	Green
7	GND	Blue
8	NC	Violet

Updates for v2

• Add resistors to feedback of speaker amplifier to add gain
• Lower values of resistors in feedback of mic amplifier to make it stable
• Lower gain of mic amplifier
• Add connection for BT audio input/output for hands free
  • Make it as module to 2.54mm pin header
  • ESP32 and ES8388 look like good choice

PMR 446 Technical Specification

• Transmit Power 500mW Estimated (REP)
• Bandwidth 12.5kHz
• Antenna Fixed, non removable. Impossible to connect to external aerial.
• Frequency Modulation and digital modes.
• User Separation CTCSS, DCS, digital signalling.
• Frequencies (Simplex TX=RX)

Channels

PMR446 Channel	Frequency (MHz)
1	446,00625
2	446,01875
3	446,03125
4	446,04375
5	446,05625
6	446,06875
7	446,08125
8	446,09375
9	446,10625
10	446,11875
11	446,13125
12	446,14375
13	446,15625
14	446,16875
15	446,18125
16	446,19375

CTCSS codes

Code	Tone Hz	Code	Tone Hz	Code	Tone Hz
0	Off	13	103.5	26	162.2
1	67.0	14	107.2	27	167.9
2	71.9	15	110.9	28	173.8
3	74.4	16	114.8	29	179.9
4	77.0	17	118.8	30	186.2
5	79.7	18	123.0	31	192.8
6	82.5	19	127.3	32	203.5
7	85.4	20	131.8	33	210.7
8	88.5	21	136.5	34	218.1
9	91.5	22	141.3	35	225.7
10	94.8	23	146.2	36	233.6
11	97.4	24	151.4	37	241.8
12	100.0	25	156.7	38	250.3

R124 Notes

Connectors

R124 A-1

Cont.		Cont.		Cont.
a1	NC	b1	+26V	c1	NC
a2	NC	b2	R112 Speaker	c2	GND
a3	R112 PTT	b3	R112 MIC-	c3	MIC+
a4	A-2 R112 Speaker	b4	A-2 R123 MIC+	c4	A-2 R112 MIC+
a5	A-2 R123 Speaker	b5	A-2 R123 MIC-	c5	A-2 R112 MIC-
a6	Tangenta Speaker	b6	Tangenta Intercom PB	c6	Tangenta GND
a7	Tangenta MIC+	b7	Tangenta MIC-	c7	Tangenta PTT
a8	Intercom Speaker for A-2, A-3, A-4, A-5	b8	Intercom PB	c8	GND
a9	+22V for A-2, A-3, A-4, A-5	b9	Intercom MIC to PA	c9	R123 PTT
a0	R123 Speaker	b0	R123 MIC+	c0	R123 MIC-

Intercom MIC to PA - Amplified microphone

R124 A-2

Cont.		Cont.
a1	A-1 R112 MIC+	b1	A-1 R123 MIC+
a2	A-1 R112 MIC-	b2	A-1 R123 MIC-
a3	Tangenta PTT	b3	Tangenta MIC+
a4	Intercom MIC to PA	b4	Tangenta MIC-
a5	GND	b5	A-1 R112 Speaker
a6	+22V for A-2, A-3, A-4, A-5	b6	A-1 R112 PTT
a7	Tangenta Speaker	b7	A-1 R123 Speaker
a8	Intercom Speaker	b8	A-1 R123 PTT