Midland 77 Schematic
8
B+
TX=GND
D D
B + = ALWAYS 8 VDC
BRX = 8 VDC IN RX
BTX = 8 VDC IN TX
PLL = 8 VDC
BRX 8V
C C
Q104
Q104
MPS9426
MPS9426
D101
D101
C118
C118
1S2473
1S2473
10n
10n
R1008
R1008
22K
22K
B B
R505
R505
82R
82R
D102
D102
1S2473
1S2473
7
CHANNEL
SWITCH
10
C202
C202
10n
10n
© Euro Radio Co
C105
C105
C106
C106
10u
10u
47n
47n
R102
R102
T5
18R
18R
3203143T53203143
C116
C116
47p
47p
C117
C117
10n
10n
C1014
C1014
R185
R185
10n
10n
820R
820R
6
PLL 8V
PLL 8V
C201
C201
C200
C200
10n
10n
10n
10n
D107
D107
GND
1S1555
1S1555
IC102
IC102
1
P1
T/R
2
P2
3
P3
FIN
4
P4
5
P5
VCC
6
P6
7
TEST
AO
8
CH19
9
CH9
MC
PD
LD
GND
RO
RI
LC7136
LC7136
C198
C198
20
33p
33p
19
R152
R152
18
10K
10K
R153
R153
17
33K
33K
16
AI
R154
R154
C1991uC199
2K2
2K2
15
14
X101
X101
C203
C203
13
10.240 Mhz
10.240 Mhz
27p
27p
12
11
C204
C204
C205
C205
56p
56p
35p
35p
R1551KR155
1u
1K
C1135pC113
5p
Q113
Q113
MPS9246
MPS9246
C206
C206
20p
20p
C2075pC207
5p
C214
C214
C213
C213
10n
10n
10u
10u
R156
R156
150K
150K
L116
L116
3204139
3204139
C211
C211
27p
27p
C212
C212
120p
120p
R158
R158
100K
100K
R157
R157
4K7
4K7
C208
C208
68n
68n
B+
R104
C101
C101
10n
10n
C1013
C1013
C102
C102
10n
10n
R104
R105
R105
82K
82K
2K7
2K7
47n
47n
R101
R101
2K2
2K2
C103
C103
10p
10p
L101
L101
L102
L102
3204117
3204117
3203164
3203164
Q101
Q101
MPS9426
MPS9426
C234
C234
4u7
4u7
Q102
Q102
MPS
MPS
9426
9426
C225
C225
150p
150p
Q103
Q103
MPS
MPS
9426
9426
C114
C114
150p
150p
C115
C115
47n
47n
C124
C124
C123
3204126
3204126
C107
C107
C123
100u
100u
10n
10n
L103
L103
CF1
CF1
10.7
10.7
10n
10n
R183
R183
470R
470R
R106
R106
470R
470R
NOTES:
Diodes 1S2473 and MA150 can be replaced with 1N4148.
Diodes OA90 can be replaced with 1N60.
Noise TX audio, check C176 known to go low, replace with 16-volt type.
Low TX audio, check FM Pre-Set RV105, know to go o/c.
TX audio clipping at HI frequency, check D111 to D114.
TX audio clipping at LOW frequency, check C181.
Output power very low about 100 to 200 mw, Check Q110 go low gain.
VCO will not lock, check C219 known to give problems.
Squelch not working, check D1001 and D104. Replace with 1N60.
TP1
TP1
VCO
VCO
C209
C209
22n
22n
FM MOD
R189
R189
390R
390R
5
© Euro Radio Co
R159
R159
47K
47K
C215
C215
27p
27p
C2185pC218
5p
C219
C219
36p
36p
R160
R160
22K
22K
D109
D109
MV2209
MV2209
R163
R163
100K
100K
C109
C109
10n
10n
C110
C110
16
AMP
AMP
1
2
27p
27p
C221
C221
33p
33p
D110
D110
MV2209
MV2209
C223
C223
10n
10n
L105
L105
R114
R114
3202762
3202762
2K2
2K2
3
Vcc
Vcc
MIX
MIX
3456789
CF2
CF2
455
455
123
C127
C127
68n
68n
BRX 8V
MPS9246
MPS9246
LIMIT
LIMIT
C125
C125
B+
R161
R161
220K
220K
Q114
Q114
MPS9246
MPS9246
C217
C217
220p
220p
Q115
Q115
R162
R162
2K7
2K7
C216
C216
120p
120p
R164
R164
3K3
3K3
R117
R117
68K
68K
8
DEMOD
DEMOD
C128
C128
10p
10p
R1007
R1007
39K
39K
R116
R116
4K7
4K7
R120
R120
5K6
5K6
C135
C135
R115
R115
10p
10p
2K2
2K2
C126
C126
68n
68n
C133
C133
C139
C139
10n
10n
R118
R118
470R
470R
C136
C136
R1020
R1020
10n
10n
2K2
2K2
R124
R124
C227
C227
100K
100K
10n
10n
Q107
Q107
27p
27p
MPS9623
MPS9623
FILTER
FILTER
68n
68n
IC101
IC101
MC3357
MC3357
10
MPS9623
MPS9623
AMP
AMP
R1121MR112
1M
C1321nC132
1n
C1311nC131
1n
C238
C238
470n
470n
R1261KR126
1K
R125
R125
100K
100K
Q108
Q108
4
R135
R135
150K
150K
111415
C134
C134
470n
470n
R131
R131
10K
10K
R1006
R1006
1K2
1K2
C228
C228
10n
10n
D1013
D1013
OA90
OA90
3
RV501
RV501
470R
470R
BTX 8V
R140
R140
R139
R139
C121
C121
10n
10n
L107
L107
3203187
3203187
C193
C193
15p
15p
L109
L109
Q109
Q109
3203187
3203187
MPS9246
MPS9246
R136
R136
C195
C195
390R
390R
10n
10n
C194
C194
82p
82p
100R
100R
4K7
4K7
C190
C190
10n
10n
3203901
3203901
R138
R138
4K7
4K7
C229
C229
82p
82p
Q110
Q110
MPS9246
MPS9246
R137
R137
2K7
2K7
R142
R142
68R
68R
C192
C192
C191
C191
10n
10n
10n
10n
L108
L108
R1431KR143
1K
Q111
Q111
C189
C189
330p
330p
2SC2314
2SC2314
R141
R141
68R
68R
C235
C235
10n
10n
LOW POWER
R144
R144
R501
R501
10R
10R
330R
330R
1 WATT
1 WATT
L126
L126
1uH
1uH
C167
C167
60p
60p
L110
L110
3205208
3205208
L123
L123
6u8H
6u8H
R146
R146
C166
C166
68R
68R
220p
220p
BTX 8V
R122
R122
10K
10K
D116
D116
MA150
MA150
13
SQUELCH
SQUELCH
TRIGGER
TRIGGER
12
D104
D104
R123
R123
D1001
D1001
OA90
OA90
100K
100K
OA90
OA90
R1009
R1009
C1371uC137
90K
90K
1u
D105
D105
OA90
OA90
C10021uC1002
1u
C226
C226
10n
10n
2626
10K
10K
2525
SQUELCH
SQUELCH
R1004
R1004
33K
33K
2424
R506
R506
1K2
1K2
TH1
TH1
300r
300r
RV101
RV101
C129
C129
10n
10n
RV102
RV102
S METER
S METER
2K2
2K2
SQUELCH
SQUELCH
PRESET
PRESET
RV103
RV103
22K
22K
RF METER
RF METER
10K
10K
2222
50KA
50KA
VOLUME
VOLUME
R502
R502
180R
180R
2323
C502
C502
10uF
10uF
C150
C150
68p
68p
2121
C142
C142
10n
10n
GG
R315 TO R318 = 1K2
IC106
IC106
VCC7Q1
Q2
8
Q3
I/P
Q4
1
Q5
GND
TL489
TL489
GND
2
SW1
SW1
HI/LOW POWER
HI/LOW POWER
LOW
LOW
13.8V
HI
HI
R148
R148
L124
L124
1K2
1K2
0.5uH
0.5uH
C161
C161
100p
100p
L111
L111
L112
L112
3201424
3201424
3200328
3200328
0.3uH
C162
C162
100p
100p
R147
R147
5R6
5R6
Q112
Q112
2SC2078
2SC2078
1/2W
1/2W
C163
C163
560p
560p
13.8V
C149
C149
180p
180p
4
4
5
5
1
1
6
6
IC104
IC104
R132
R132
KIA7217AP
KIA7217AP
820R
820R
7
7
9
9
3
3
R133
R133
330R
330R
C151
C151
33u
33u
C143
C143
2n2
2n2
C148
C148
4u7
4u7
0.3uH
C164
C164
C1581pC158
R196
180p
180p
C159
C159
27p
27p
C155
C155
10n
10n
C154
C154
68n
68n
C146
C146
220u
220u
C147
C147
47u
47u
2
2
10
10
8
8
C141
C141
220p
220p
C144
C144
68n
68n
R196
1p
47K
47K
C165
C165
180p
180p
R1491KR149
1K
D106
D106
OA90
OA90
L118
L118
JK1
JK1
0.8uH
0.8uH
EXT SPKR
EXT SPKR
R134
R134
L121
L121
4R7
4R7
0.8uH
0.8uH
2020
2W
2W
1919
C153
C153
10n
10n
1
L113
L113
L115
L115
3201424
3201424
0.5uH
0.5uH
C169
C169
80p
80p
C172
C172
180p
180p
SP1
SP1
SPEAKER
SPEAKER
L201
L201
22uH
22uH
PL259
PL259
BNC
BNC
C301
C301
120p
120p
R504
R504
4K7
4K7
CHASSIS
RX=GND
2
3
4
5
6
LED1-4
RX=GND
© Euro Radio Co
C179
C179
10u
10u
GND
R178
R178
4K7
4K7
R177
R177
C178
C178
220K
220K
411
10n
10n
2
-
-
1
3
+
+
IC105A
IC105A
LM324
LM324
R176
R176
22K
C177
C177
47u
47u
22K
C176
C176
10u
10u
TX=GND
1212
L202
L202
22uH
22uH
R181
R181
1K2
1K2
R182
R182
6K8
6K8
1111
MIC SKTMIC SKT
1
425
C304
C304
10n
A A
10n
MIC AUDIO
3
C303
C303
C302
C302
10n
10n
10n
10n
D115
D115
1S2473
1S2473
C175
C175
47n
47n
R180
R180
10K
10K
R179
R179
4K7
4K7
B+
R151
R151
470R
470R
D111 To D114
ARE 1S2473
R174
R174
220K
220K
6
-
-
7
R175
R175
2K7
2K7
R172
R172
5
10K
10K
+
+
IC105B
IC105B
LM324
LM324
C181
C181
R150
R150
R10K
R10K
R169
R169
20K
20K
C183
C183
10n
10n
IC105C
IC105C
LM324
LM324
9
-
-
8
R170
R170
R171
R171
10
10K
10K
+
10K
10K
C182
C182
15n
15n
+
R168
R168
10K
10K
RV105
RV105
22K
10n
10n
22K
R1011
R1011
10K
10K
C2221nC222
1n
FM MOD
1515
+
C170
C170
10n
10n
-
1616
CH101
CH101
CHOKE
CHOKE
L125
L125
10uH
10uH
D108
D108
1N4003
1N4003
C171
C171
10n
10n
SW2
SW2
1818
ON/OFF
ON/OFF
© Euro Radio Co
13.8V SW
1010
C156
C156
1000u
1000u
1
IC103
LM7808
C157
C157
47n
47n
R186
R186
220R
220R
C196
C196
10u
10u
R109
3
2
C185
C185
100u
100u
R109
Q105
Q105
390R
390R
MPS9681
MPS9681
C241
C241
R1101KR110
10n
10n
1K
C184
C184
10n
10n
TX=GND
B+
PLL 8V
L122
L122
25uH
25uH
C197
C197
C236
C236
47n
47n
BRX 8V
B + = ALWAYS 8 VDC
BRX = 8 VDC IN RX
BTX = 8 VDC IN TX
PLL = 8 VDC
10n
10n
BTX 8V
D103
D103
1S2473
1S2473
R111
R111
4K7
4K7
DRAWN BY: Rick Jackson Euro Radio Co
DRAWN BY: Rick Jackson Euro Radio Co
DRAWN BY: Rick Jackson Euro Radio Co
Size Document Number Rev
Size Document Number Rev
8
7
6
5
4
3
2
MIDLAND 77-805
Size Document Number Rev
MIDLAND 77-805.SCH
MIDLAND 77-805.SCH
MIDLAND 77-805.SCH
Date: Sheet
Date: Sheet
Date: Sheet
1
of
11Wednesday, November 28, 2007
of
11Wednesday, November 28, 2007
of
11Wednesday, November 28, 2007
1.1
1.1
1.1
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