Audio processor for communications transmitter

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STD Audio processor for communications transmitter

License: Public Domain

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Update time： 2020-06-13 18:58:04

Creation time： 2020-03-28 17:12:27

Description

Audio processor for communications transmitter. Used in my ham radio station to improve audio intelligility for contest use. It is a bit of an overkill but I used it to learn lots about equalisation and speech compression. Uses LA3600 equaliser plus SSM2167 speech compressor. (My first surface mount component with 0.5 mm pin pitch, learned lots about reflow soldering with a hot air gun). Also has a recorder chip ISD 1760 to make CQ Contest calls. Balanced transformer on the output to minisise audio loop noise problems. Multiple connectors to accomodate different microphones, avaition headset, PC mic and Yaesu 9 pin mic. Housed in Hammond diecast box.

Design Drawing

schematic diagram

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Audio Processor - as manufactured
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Audio Processor - with post pcb manufacure updates
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PCB

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PCB v0_1 as manufactured
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PCB post manu v1_1 corrected label on buttons connector
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BOM

BOM download Purchase Parts

ID	Name	Designator	Footprint	Quantity
1	1N4448	D1	DO-35	1
2	LA3600	U3	DIP16	1
3	BC557A	Q2	SOT54	1
4	10k	R2,R4	AXIAL-0.3	2
5	470R	R3	AXIAL-0.3	1
6	82k	R12	AXIAL-0.3	1
7	4k7	R15	AXIAL-0.3	1
8	100k	R14,R4	AXIAL-0.3	2
9	470k	R16	L0805	1
10	180R	R10	AXIAL-0.3	1
11	Or	R13	L1206	1
12	1k	R5,R6,R7	AXIAL-0.3	3
13	22 uF	C33	CAP-D3.0XF1.5	1
14	47 uF	C16	CAP-D3.0XF1.5	1
15	3.3 uF	C34	CAP-D3.0XF1.5	1
16	3.3uF	C9	CAP-D3.0XF1.5	1
17	1uF	C3,C2	CAP-D3.0XF1.5	2
18	180 R	R8,R9,R1	AXIAL-0.3	3
19	ISD1700SY	U2	PDIP-28_L38.1-W12.7-P2.54-LS15.3-BL	1
20	XFMR	T1	TRANSFORMER_ 600 OHM 1:1	1
21	1nF	C6,C5	1206	2
22	1u	C8	1206	1
23	1u	C1	CAP-D3.0XF1.5	1
24	100uH	L1	AXIAL-0.4	1
25	Mic In	H1	DIP-1X5P-2.54MM-M	1
26	REC	LED1	LED-3MM/2.54	1
27	PWR ON	LED2	LED-3MM/2.54	1
28	100K	VR2,VR3,VR4,VR5,VR6	RES-ADJ-TH_3362P	5
29	0.1u	C27,C30,C38,C17,C20,C26,C19	L1206	7
30	4u7	C31	RAD-0.1	1
31	1u	C29,C18,C36,C35	L1206	4
32	10u	C37,C39,C10	L1206	3
33	1000p	C32	RAD-0.1	1
34	0.1 NF	C28	RAD-0.1	1
35	1nF	C4,C7	RAD-0.1	2
36	2N3904	Q1	TO-92(TO-92-3)	1
37	Rec	SW-2SWITCH	SMD-BUTTON	1
38	Play	SW-3SWITCH	SMD-BUTTON	1
39	Erase	SW-4SWITCH	SMD-BUTTON	1
40	PTT	SW-1SWITCH	SMD-BUTTON	1
41	SSM2167	U5	MSOP10	1
42	HE721A0510	U4	LITTELFUSE HE700	1
43	1K	VR8,VR9,VR10,VR7	RES-ADJ-TH_3362P	4
44	Threshold 5k	VR12	RES-ADJ_3362P	1
45	Rig Interface	H2	210S-1X8P	1
46	Compression 180 k	VR11	RES-ADJ-TH_3362P	1
47	10k Pot	VR1	BOURNS PVT09A-4 SINGLE ROT VER	1
48	Buttons	U1	6 PIN HEADER	1
49	39nF	C25	L1206	1
50	3.9nF	C23	RAD-0.1	1
51	390pF	C21	L1206	1
52	680nF	C15	RAD-0.2	1
53	220nF	C14	RAD-0.1	1
54	68nF	C13	L1206	1
55	22nF	C12	RAD-0.1	1
56	6.8nF	C11	RAD-0.1	1
57	1.2nF	C22	L1206	1
58	12nF	C24	RAD-0.1	1