Heathkit SB-401 - Page 2

TABLE OF
INTRODUCTION .... 2... 2.2.2.2 ee eee eee eee 3
UNPACKING INSTRUCTIONS .........--220+0+ 205 4
CIRCUIT BOARDS
Mixer-Bandpass Circuit Board
Parts: List $F 9 % <¢ asec 5 ca St Ne EAL aay Swe 5
Step-By-Step Assembly ... 2... ...-..-22 2502008. 6
Carrier Generator Circuit Board
Parte List #2) 4.02 dhe eho x yee Sod eS ee eee 8
Step-By-Step Assembly .. 2... 2.2... 2 ee ee ee eee 10
CHASSIS PARTS MOUNTING
Parts: List #3. «3 -Sxc. ees) wenn go ete eel ee WE al ees oe 13
Step-By-Step Assembly
Parts Mounting-Chassis Bottom... 1. ee ee es 16
Coil Mounting-Chassis Top 6 1 we ee ee 21
Parts Mounting-ChassisTop .. 2... 2. pee eee eee 24
CHASSIS WIRING
Parts List#4. 5'p. este ois? Sogn, ae ch ae Sak ne EV EO ES 33
Step-By-Step Assembly
Preliminary WiringChassis Top «6... ee ee ee ee ee 35
Preliminary Wiring-Chassis Bottom .............--. 39
Parts Mounting On Carrier Generator Shield 2... .....2.2. 54
Wiring Carrier Generator Shield To Chassis . 2... ....... 55
Transformer Wiring .. 2... ee ee eee 63
Preliminary Wiring-Band Switch .. 2... 2. ee eee eee 64
FINAL WIRING
Parts List: #535. ose 3.8 Sc fap ea ay hep esa ays AROS BRE 73
Step-By-Step Assembly
Dial Assembly «1. 75
Parts Mounting-Front Panel 2. 2. 2. ee ee ee 78
Wiring Front Panel To Chassis... . 2... 27 ee eee eee 79
Front Panel Mounting . 2... 2 ee ee ee ee 81
Final Wiring-Chassis Top 6 6 1 we ee ee ee ee ee 82
Final Wiring-Chassis Bottom... 6... ee ee ee ee ee 85
INITIAL TEST iz oie d,s: Sc eas ga ee ee hee ad 87
ALIGNMENT
Alignment With SB-303 Receiver As A Transceiver... 2... 2. ee 90
8.6 Megahertz Trap .. 2... 2. eee ee eee ee 90
21 Megahertz Trap 2... 1. ee ee ee ee ee 90
Carrier Generator... 6. 2. ee ee ee 90
Drivers si. kee eed hie, De US oar Ea re ate Y 91
8.6 Megahertz Trap Adjustment .. 1... ...... 0004. 92
Carrier Null Adjustment . 2... 1. ee ee ee 93
Neutralizivig:. 2.6. -3/ sr) got. ee 8) So vee eo ee ha Tae i ee 94
Pinal Bias. ¢>:s-2iever soa Ge PS ly oe Gee ce EME BA eg es 94
Microphone Connection .. 2... 6 2 ee ee ee ee 95
LMO Adjustment ... 2... 2. eee ee ee ee ee 95
Final Transmitter Adjustment . 2... 6... ee eee 96
Alignment With SBA-401-1 Crystal Accessory Kit Installed
Crystal Installation 2... 1. ee ee ee 96
Equipment Required ....... Mao satte, oun riee dea, aabncuy tN, 97
8.6 Megahertz Trap - - -- - - ee ee ee 97
Page 2
CONTENTS
21 Megahertz Trap .. 2... ee ee ee eee ee 97
Heterodyne Oscillator... 2. ee ee 97
Carrier Generator. 2 2. ee ee 97
Driver ics, 5-8 Ane ie, PE oie a EE ls 98
8.6 Megahertz Trap Adjustment ................. 99
Carrier Null Adjustment .. 2... 2. 2 ee ee 99
Neutralizing oc. 608 Seer eek a ahd Ge AK se ie He ae 99
Pinal Blas: > 46 \cg-0 hbo op tee dae Bead. ae hee @, Se Sarde 100
Microphone Connection . 2... 01. 101
LMO Adjustment .. 2... 0. 0. ee es 101
Frequency Shift Adjustment .. 2... 0. ........0.. 102
Final Transmitter Adjustment ..............0004 102
FINAL ASSEMBLY .........0.0.-0. 2-000 e eee 103
INSTALLATION
AND
OPERATION
...............0.
105
Meter
Readings
2...
2...
108
Reading
Transmitter
Frequency
................,
108
Operating
Conditions
2.2...
ee
109
Transmitter
Operation
©...
1.
109
Operation With SB-303 Receiver»... 2... en 109
CW ie Re Soe Rese Ske iG S, oe dee Ee ME a he 110
SOBY vies ota eae eA ane Oke Ae a etatat gestae Buy Bas Sle wos lll
Transmitter Operation Only . 2... 20... 0.000 0000 8 1i2
CWTuneUp 2... ee ee 113
SSB Tane-Upr ics. 303 sect co soy te a a ete ok ae Hee 115
INCASE OF DIFFICULTY .................000. 117
Troubleshooting Chart»... ee ee 118
Factory Repair Service 2 2. ee 120
SPECIFICATIONS 2.1... ee ee 121
CIRCUIT DESCRIPTION
Schematic Diagram 2... 6. ee ee 125
Frequency Chart 2. 6. 2 ee ee ee 125
Audio Preamplifier And Cathode Follower ............ 126
VOX Amplifier 2... ee ee ee es 126
Relay And Anit-VOX Amplifier ...............00. 126
Tone Oscillator And Tone Amplifier ......-.....00.0. 128
LSB-USB-CW Carrier Generator And
Cathode Follower . 6 6 1 1 we ee 129
Balanced Modulator . 2 2. 1. 6 ee ee 130
Isolation Amplifier 2... 2. 1 ee ee 130
Symmetrical Crystal Bandpass Filter... 2... 2. ee 131
Linear Master Oscillator 2. 2. 1 ee ee 131
EMO Mixer. te eck c an fo arches Bb ia Baca ee Sas 132
Heterodyne Oscillator And Heterodyne-Oscillator
Amplifier. «ss «22504 afer ee Pe Glare, BaD erly Gs A 132
Heterodyne Mixer 2 2. 2. ee ee 132
DRIVERS Feo sa 8 Gee see eases ey Ray Hag ES Seas eee deg Grea CaS 134
Final Amplifiers 2 2... ee ee eee 134
Automatic Level Control «2... 2. ee ee ee 134
PowerSupply’ sata es a a es 136
Metering Circuits ©. 6. eee 137
CIRCUIT BOARD X-RAY VIEWS .. 2... 2.2... ...0000. 139
CHASSIS PHOTOGRAPHS «ww we ee 141
SCHEMATIC.... « (fold-out from Page) . 2 2 2. ee ee 147
REPLACEMENT PARTS PRICELIST ........-....004.% 148
HEATHEIT®