BUILDING THE G6LBQ MULTIBAND BitX 21st January 2011 Construction of the G6LBQ Multi-band BitX is best done in stages as this will make troubleshooting much easier as any faults during the build can be narrowed down to a particular section. First of all read all documentation and carry out an inventory of parts from the suggested “Bill Of Materials”. During the build I will suggest alternative parts or component arrangements you can try to overcome any component sourcing difficulties. Please visit the BitX Yahoo Yahoo Group and make sure you have the latest documentation before commencing your build, the documentation is located in the “ Files” section of the BitX Yahoo group under folder name “ G6LBQ – Bitx”. If you are considering building the G6LBQ Multi-band BitX you can make your own PCB using the Artwork located in my Yahoo Yahoo Group BitX folder f older but I would highly recommend you purchase a ready etched, screen printed, tinned and drilled PCB from Sunil Lakhani VU3SUA who can be contacted via email:
[email protected] [email protected].. Sunil also has a website with other useful radio kits which can be found at http://amateurradiokits.in/
Multiband BitX PCB From Sunil Lakhani
Note the PCB is perfectly rectangular and it is my poor attempt at photographing the PCB which has distorted the aspect a little! PAGE 1
A Fully Populated & Completed PCB
The above photo is of a fully populated, finished and working pcb.
PLEASE use this image as a component location/value reference along with the individual construction stage images. Pay attention in all the construction stages to the correct orientation of components. There is a full PCB component layout image in the back of the manual If you are building using a PCB from Sunil Lakhani there were some errors in the silkscreen printing during the first production batch so please always use the latest documentation for component locations and orientation. IMPORTANT IMPORTANT POWER SUPPLY SUPPLY NOTE
During the construction most build stages have some voltage tests you can carry out as a basic check that the stage is functioning as expected. The voltages measure within this documentation were all taken with the PCB powered from a power supply providing exactly 13.5 volts, depending on the exact voltage of your own power supply the readings expected are likely to vary a little but probably within 5% of the readings r eadings documented.
PAGE 2
Stage One - Fitting PCB jumper links Install all wire jumpers (8 in total) onto the PCB board as illustrated below:
PAGE 3
Next Stage Two
Stage Two – RF Amplifier Section
Components list required for the RF amplifier section:
QUANTITY
VALUE
DESCRIPTION
CODE
2
10 OHM
0.25W Resistor
brn-blk-blk
2
100 OHM
0.25W Resistor
brn-blk-brn
4
220 OHM
0.25W Resistor
red-red-brn
2
1K
0.25W Resistor
brn-blk-red
2
2K2
0.25W Resistor
red-red-red
9
100NF (0.1uf)
Capacitor
104
2
1N4148
Silicon Diode
1
2N3904
NPN Transistor
1
2SC2570A
NPN Transistor
1
4 Pin Male Con
0.1 Pitch Con
FITTED
Using the photograph below as an illustration fit all parts listed in the stage two components list. Pay close attention to the orientation of the following components which must be fitted correctly: 2N3904, 2SC2570A & the two 1N4148 Diodes.
When installing the transistors note the flat side orientation, also the diodes must be mounted the correct way! If you are unable to source a 2SC2570A for Q1 it can be replaced with an MPSH10 transistor which is in current production and pin for pin compatible.
PAGE 4
Continued
With all the components in place for stage two solder a 4 pin male PCB 0.1 pitch connector to facilitate the power supply connections. Note you can of course omit the 0.1 connectors used throughout the build process and solder all connection points straight to the PCB
DO NOT APPLY VOLTAGE TO THE RECEIVE AND TRANSMIT POINTS SIMULTANEOUSLY! Using a multimeter on a current measuring range of a few hundred milliamps Connect the -VE supply rail to your power supply negative terminal and insert a multi-meter between the +13.8 VOLTS FOR RECEIVE PCB connection point and your power supply positive terminal, if everything is OK the measured current drawn in receive mode by Q1 stage should be approximately 11 mA's. Again using a multimeter on a current measuring range of a few hundred milliamps Connect the -VE supply rail to your power supply negative terminal and insert a multi-meter between the +13.8 VOLTS FOR TRANSMIT PCB connection point and your power supply positive terminal, if everything is OK the measured current drawn in transmit mode by Q10 stage should be approximately 11 mA's.
Below is a chart showing the expected voltages present on the junctions of Q1 & Q10 transistors, you can check these voltages against the chart and record your own readings for comparison and future test purposes. EXPECTED VOLTAGES FOR Q1 (2SC2570A) RECEIVE RF AMP STAGE
Expected Voltage COLLECTOR
8.76
BASE
1.995
EMITTER
2.711
Own Measured Voltage Reading Log
EXPECTED VOLTAGES FOR Q10 (2N3904) TRANSMIT RF AMP STAGE
Expected Voltage COLLECTOR
8.69
EMITTER
2.008
BASE
2.703
PAGE 5
Own Measured Voltage Reading Log
Next Stage Three
Stage Three – 1st IF RX Amplifier (Q2) & 2ND IF TX (Q9) Components list required for the stage three IF amplifier sections:
QUANTITY
VALUE
DESCRIPTION
CODE
2
10 OHM
0.25W Resistor
brn-blk-blk
2
100 OHM
0.25W Resistor
brn-blk-brn
4
220 OHM
0.25W Resistor
red-red-brn
2
1K
0.25W Resistor
brn-blk-red
2
2K2
0.25W Resistor
red-red-red
8
100NF (0.1uf)
Capacitor
104
2
1N4148
Silicon Diode
2
2N3904
NPN Transistor
FITTED
Using the photograph below as an illustration fit all parts listed in the stage three components list. Pay close attention to the orientation of the following components which must be fitted correctly: 2N3904's & the two 1N4148 Diodes.
PAGE 6
Continued
With all the components in place for stage three carry out the following checks to confirm the stage is working correctly:
DO NOT APPLY VOLTAGE TO THE RECEIVE AND TRANSMIT POINTS SIMULTANEOUSLY!
Using a multimeter on a current measuring range of a few hundred milliamps Connect the -VE supply rail to your power supply negative terminal and insert a multi-meter between the +13.8 VOLTS FOR RECEIVE PCB connection point and your power supply positive terminal, if everything is OK the measured current drawn in receive mode will be approximately 23 mA's, this is the total current now being drawn by Q2 the 1 st IF Amplifier and Q1 the RF Amplifier we assembled in stage 2. Again using a multimeter on a current measuring range of a few hundred milliamps Connect the -VE supply rail to your power supply negative terminal and insert a multi-meter between the +13.8 VOLTS FOR TRANSMIT PCB connection point and your power supply positive terminal, if everything is OK the measured current drawn will be approximately 23 mA's, this is the total current now being drawn by Q9 the 2nd IF Amplifier and Q10 the RF Amplifier we assembled in stage 2.
Below is a chart showing the expected voltages present on the junctions of Q2 & Q9 transistors, you can check these voltages against the chart and record your own readings for comparison and future test purposes. EXPECTED VOLTAGES FOR Q2 (2N3904) RECEIVE 1ST IF STAGE
Expected Voltage EMITTER
1.99
BASE
2.71
COLLECTOR
8.74
Own Measured Voltage Reading Log
EXPECTED VOLTAGES FOR Q9 (2N3904) TRANSMIT 2ND IF STAGE
Expected Voltage EMITTER
1.97
BASE
2.7
COLLECTOR
8.76
PAGE 7
Own Measured Voltage Reading Log
Next Stage Four
Stage Four – DDS/VFO Amplifier Driver For First mixer Stage Components list required for the DDS/VFO amplifier section:
QUANTITY
VALUE
DESCRIPTION
CODE
1
10 OHM
0.25W Resistor
brn-blk-blk
1
100 OHM
0.25W Resistor
brn-blk-brn
2
1K
0.25W Resistor
brn-blk-red
2
100NF (0.1uf)
Capacitor
104
1
2N3904
NPN Transistor
FITTED
Using the photograph below as an illustration fit all parts listed in the stage four components list. Pay close attention to the orientation of the 2N3904 transistor.
With all the components in place continue on with stage 5 and then we will do a joint testing of stages 4 & 5
PAGE 8
Next Stage Five
Stage Five – 1 st Mixer Section Components list required for the 1st Mixer section:
QUANTITY
VALUE
DESCRIPTION
CODE
1
100 OHM
0.25W Resistor
brn-blk-brn
1
100NF (0.1uf)
Capacitor
104
1
ADE-1
Mixer
1
IC Socket
Turned Pin Skt
FITTED
The ADE-1 mixer was chosen as it is an inexpensive device and is specified to work as high as 500Mhz so in theory it ought to be possible to use the Multiband Bitx as the heart of a 6M or even 4M SSB transceiver. As the ADE-1 is a surface mount device it will need converting to a through hole component for this project. I found the best way to convert the ADE-1 to a through hole component was to simply solder it to the top of a turned pin type IC socket but you can also fit veroboard type solder pins to the PCB and then solder the ADE-1 straight onto the solder pins. Care must be taken when soldering the ADE-1 to an IC socket or pins, use only a fine tipped soldering iron and don’t apply excessive heat to the connections, solder one connection then let the device cool down then move onto the next connection allowing a cool down period. If using a turned pin IC socket as suggested prepare the IC socket by flooding the turned pins with solder as per the illustration:
Solder the ADE-1 to the top of the IC socket being careful not to apply to much heat for too long a period:
NOTE: You can use an 8 pin IC socket and instead of the 6 pin but you will have to c ut off 2 of the unused pins on the socket as the PCB only has holes for the six pins actually needed.
PAGE 9
Continued
Using the photograph below as an illustration fit all parts listed in the stage five's components list. Pay close attention to the orientation of the ADE-1 device.
With all the components in place for stage four & five carry out the following checks to confirm these stages are working correctly:
DO NOT APPLY VOLTAGE TO THE RECEIVE AND TRANSMIT POINTS FOR THIS TESTING PHASE! Testing of stage four/five is similar to the previous testing phases but this time we need to connect the power supply to the boards “All Time” +VE connection. The “All Time” supply point supplies power to all stages that require power in both receive and transmit modes. The connection is illustrated below:
PAGE 10
Continued
Using a multimeter on a current measuring range of a few hundred milliamps Connect the -VE supply rail to your power supply negative terminal and insert a multi-meter between the ALL TIME +Ve PCB connection point and your power supply positive terminal, if everything is OK the measured current drawn should be approximately 43 mA's.
Below is a chart showing the expected voltages present on the junctions of Q3 transistors and ADE1 mixer device, you can check these voltages against the chart and record your own readings for comparison and future test purposes. EXPECTED VOLTAGES FOR Q3 (2N3904) DDS/VFO RF AMP STAGE
Expected Voltage COLLECTOR
9.27
EMITTER
3.78
BASE
4.5
Own Measured Voltage Reading Log
EXPECTED VOLTAGES FOR ADE-1 MIXER STAGE 1
Expected Voltage PIN 1
9.26
PIN 6
9.26
PINS 2,3,4,5
0 Volts
PAGE 11
Own Measured Voltage Reading Log
Next Stage Six
Stage SIX – 2ND IF Amplifier Receive Section Components list required for the 2 nd IF amplifier receive section:
QUANTITY
VALUE
DESCRIPTION
CODE
1
100 OHM
0.25W Resistor
brn-blk-brn
1
220 OHM
0.25W Resistor
red-red-brn
1
15K
0.25W Resistor
brn-green-orange
2
10NF (0.01uf)
Capacitor
103
3
100NF (0.1uf)
Capacitor
104
1
MC1350P
Integrated Circuit
1
IC Holder 8 Pin
8 Pin DIL
1
1N4148
Silicon Diode
1
60PF (optional)
Murata Trimmer
FITTED
Brown
Using the photograph below as an illustration fit all parts listed in the stage six components list. Pay close attention to the orientation of the MC1350P Integrated Circuit and 1N4148 Silicon Diode.
NOTE! Transformer T1 is a 10.7Mhz IF transformer (recovered from an old CB Radio), it may or may not be necessary to fit the 60PF brown coloured trimming capacitor in order to tune the IF coil, some IF coils have an internal capacitor fitted so resonance may be achievable without the trimmer. The 60PF trimmer is manufactured by Murata, if it is not readily available from your own component supplier you can substitute this for a more common 22PF trimmer and experiment by adding an additional small parallel ceramic capacitor of a few picofarads & gradually increasing the value until a peak in signal can be found by either adjusting T1 or the trimmer. The arrangement of T1 & the trimmer capacitor should easily provide sufficient coverage for IF frequencies between 9 & 11 Mhz.
PAGE 12
Continued
If you decide to purchase a PCB from Sunil Lakhani I recommend you ask him if he can supply one of the coils he uses in the bandpass filter from his 20Mtr BitX3 kit as this coil has been tested and works fine along with an additional fixed value ceramic padding capacitor of 82PF. As an alternative to the TOKO style IF can a very suitable coil can be wound on an Amidon toroid type T37-2 (Red), wind 26 turns primary and 2 turns secondary using #24 or #26 gauge enamel covered copper wire. The coil will need padding with a fixed ceramic capacitor of 33PF and the installation of a 22PF trimmer for tuning:
With all the components in place for stage six carry out the following checks to confirm the stage is working correctly:
DO NOT APPLY VOLTAGE TO THE RECEIVE AND TRANSMIT POINTS SIMULTANEOUSLY! Using a multimeter on a current measuring range of a few hundred milliamps Connect the -VE supply rail to your power supply negative terminal and insert a multi-meter between the +13.8 VOLTS FOR RECEIVE PCB connection point and your power supply positive terminal, if everything is OK the measured current drawn in receive mode will be approximately 37 mA's, this is the total current now being drawn by Q1 the RF Amplifier, Q2 the 1 st IF Amplifier and the completed stage six 2 nd IF amplifier.
Below is a chart showing the expected voltages present on the MC1350P integrated circuit, you can check these voltages against the chart and record your own readings for comparison and future test purposes. EXPECTED VOLTAGES FOR IC2 RECEIVE 2ND IF STAGE
Expected Voltage PIN 1 & 2
11.3
PIN 3 & 7
Ground
PIN 4
3.86
PIN 5
5.65
PIN 6
3.86
PIN 8
11.3
PAGE 13
Own Measured Voltage Reading Log
Next Stage Seven
Stage Seven – 1ST IF Amplifier Transmit Section Components list required for the 1st IF amplifier transmit section:
QUANTITY
VALUE
DESCRIPTION
CODE
1
4.7 OHM
0.25W Resistor
yell-violet-gold
1
100 OHM
0.25W Resistor
brn-blk-brn
1
220 OHM
0.25W Resistor
red-red-brn
1
470 OHM
0.25W Resistor
yell-violet-brown
1
1K
Capacitor
brn-blk-red
1
2K2
Capacitor
red-red-red
4
100NF (0.1uf)
Capacitor
104
1
1N4148
Silicon Diode
1
2N3904
NPN Transistor
FITTED
Using the photograph below as an illustration fit all parts listed in the stage seven components list. Pay close attention to the orientation of the following components which must be fitted correctly: 2N3904 transistor & 1N4148 silicon diode.
PAGE 14
Continued
With all the components in place for stage seven carry out the following checks to confirm the stage is working correctly:
DO NOT APPLY VOLTAGE TO THE RECEIVE AND TRANSMIT POINTS SIMULTANEOUSLY! Using a multimeter on a current measuring range of a few hundred milliamps Connect the -VE supply rail to your power supply negative terminal and insert a multi-meter between the +13.8 VOLTS FOR TRANSMIT PCB connection point and your power supply positive terminal, if everything is OK the measured current drawn in transmit mode will be approximately 32 mA's, this is the total current now being drawn by Q9 2 nd IF Amplifier, Q10 RF Amplifier & Q8 the 1st IF Amplifier.
Below is a chart showing the expected voltages present on transistor Q8 2N3904, you can check these voltages against the chart and record your own readings for comparison and future test purposes. EXPECTED VOLTAGES FOR Q8 (2N3904) TRANSMIT 1ST IF STAGE
Expected Voltage COLLECTOR
10.1
EMITTER
2.4
BASE
3.1
PAGE 15
Own Measured Voltage Reading Log
Next Stage Eight
Stage Eight – 2ND Mixer Section Components list required for the
QUANTITY
2nd
VALUE
Mixer section:
DESCRIPTION
CODE
1
ADE-1
Mixer
1
22 OHM
0.25W Resistor
red-red-blk
2
220 OHM
0.25W Resistor
red-red-brown
1
IC Socket
Turned Pin Skt
FITTED
As per stage five care must be taken when soldering the ADE-1 to the IC socket or pins, use only a fine tipped soldering iron and don’t apply excessive heat to the connections, solder one connection then let the device cool down then move onto the next connection allowing a cool down period. Using the photograph below as an illustration fit all parts listed in stage eights components list. Pay close attention to the orientation of the ADE-1 device.
That completes stage eight, there is no initial testing for this stage.
PAGE 16
Next Stage Nine
Stage Nine – Carrier Oscillator Section Components list required for the carrier oscillator section: QUANTITY
VALUE
DESCRIPTION
CODE
1
100 OHM
0.25W Resistor
brn-blk-brn
3
1K
0.25W Resistor
brn-blk-red
1
5K6
0.25W Resistor
grn-blu-red
1
120K
0.25W Resistor
brn-red-yell
3
2N3904
NPN Transistor
1
Carrier Xtal
Freq To Suit IF
1
4.7uh
Inductor
1
22PF
Murata Trimmer
Red
1
30PF
Murata Trimmer
Green
2
220PF
NP0 Capacitor
221
2
100NF (0.1uf)
Capacitor
104
1
10NF (0.01uf)
Capacitor
103
2
47UF 50Volt
Electrolytic Cap
1
78L09
Regulator
FITTED
The carrier insertion oscillator comprises of a colpitts oscillator, buffer stage and switching transistor for USB/LSB selection. The frequency of the carrier xtal will be dependant on the choice of IF frequency used. Common IF frequencies for this project inc 9Mhz, 10Mhz, & 11Mhz The components list for this stage details a 22 PF and 30PF trimming capacitors for the carrier adjustments (USB/LSB) you can however use 22PF trimmers in both locations and add additional padding capacitors to the trimmers if required. The PCB has additional pads/holes for fitting padding capacitors should it be found necessary. If using a 22PF (Murata Red) trimmer in place of the suggested Green 30PF trimmer you could try adding a 8.2PF NP0 type capacitors as padding.
PAGE 17
Continued
Using the photograph below as an illustration fit all parts listed in the section nine's components list but do not fit Q4 the 2N3904 adjacent to the T1 2 nd IF can just yet! Pay close attention to the orientation of the 2N3904 transistors, 78L09 regulator & 47uf electrolytic capacitors.
Fit a 2 Pin PCB 0.1 pitch connector to facilitate the connection of a USB/LSB switch or omit and hard wire a switch straight to the PCB after completion. Unfortunately when drawing out the PCB for this project I made an error in the pad positions for transistor Q4 so a little work around is required to correct this. Please take the remaining transistor for Q4 location and sleeve the base and emitter legs with approximately 6mm of thin sleeving and reform the transistor legs as shown and solder in place as above.
You may if you prefer substitute Q4 – 2N3904 for a general purpose silicon NPN transistor with pin-outs to match the PCB pads/holes.
PAGE 18
Continued
With all the components in place for stage nine carry out the following checks to confirm the stage is working correctly:
DO NOT APPLY VOLTAGE TO THE RECEIVE AND TRANSMIT POINTS SIMULTANEOUSLY! Using a multimeter on a current measuring range of a few hundred milliamps Connect the -VE supply rail to your power supply negative terminal and insert a multi-meter between the ALL TIME +Ve PCB connection point and your power supply positive terminal, if everything is OK the measured current drawn in receive mode will be approximately 53 mA's, this is the total current now being drawn by Q3 transistors, ADE-1 mixer number 1, Q5 & Q6 the carrier oscillator and buffer amp transistors.
If you have a frequency counter you can connect this to the emitter junction of Q6 or 0.1uf mixer coupling capacitor and check that the oscillator is running. Below is a chart showing the expected voltages present on the 78L09 regulator and the junctions of Q5, Q6 & Q4 transistors, you can check these voltages against the chart and record your own readings for comparison and future test purposes. EXPECTED VOLTAGES FOR 78L09 REGULATOR
Expected Voltage OUTPUT PIN
Own Measured Voltage Reading Log
8.9 EXPECTED VOLTAGES FOR Q5 (2N3904) OSCILLATOR
Expected Voltage COLLECTOR
8.07
EMITTER
4.3
BASE
4.6
Own Measured Voltage Reading Log
EXPECTED VOLTAGES FOR Q6 (2N3904) OSCILLATOR BUFFER STAGE
Expected Voltage COLLECTOR
8.07
EMITTER
3.9
BASE
4.29
Own Measured Voltage Reading Log
EXPECTED VOLTAGES FOR Q4 (2N3904) USB/LSB SWITCH
Expected Voltage COLLECTOR EMITTER BASE
PAGE 19
Own Measured Voltage Reading Log
0 Volts or millivolts. Later when the USB/LSB switch is fitted voltages will depend on switch position! Next Stage Ten
Stage Ten – Audio Output Amplifier Components list required for the audio output section: QUANTITY
VALUE
DESCRIPTION
CODE
1
2R7 OHM
0.25W Resistor
red-vio-gold
1
10 OHM
0.25W Resistor
brn-blk-blk
1
220 OHM
0.25W Resistor
red-red-brn
1
4k7
0.25W Resistor
yell-vio-red
1
120K
0.25W Resistor
brn-red-yell
3
100uf 25Volt
Electrolytic Cap
1
47uf 50Volt
Electrolytic Cap
2
1uf 50Volt
Electrolytic Cap
2
100NF (0.1uf)
Capacitor
1
1N4148
Silicon Diode
1
2N3904
NPN Transistor
1
LM380-8
Integrated Circuit
1
IC Socket
8 Pin DIL
2
47UF 50Volt
Electrolytic Cap
1
78L09
Regulator
1
4k7
Potentiometer
FITTED
104
Using the photograph below as an illustration fit all parts listed in the stage Ten's components list. Pay close attention to the orientation of the 2N3904 transistor, 1N4148 silicon diode, LM380-8 integrated circuit & all electrolytic capacitors.
PAGE 20
Continued
Fit a 5 Pin & 2 Pin PCB 0.1 pitch connectors to the PCB to facilitate the connection of the 4K7 volume control and speaker, if you are not using the 0.1 PCB connectors make some temporary connections so the stage can be tested. Refer to the final connections and wiring illustration at the end of the manual for details on connecting the 4K7 volume control and speaker. With all the components in place for stage ten carry out the following checks to confirm the stage is working correctly:
DO NOT APPLY VOLTAGE TO THE RECEIVE AND TRANSMIT POINTS SIMULTANEOUSLY! Using a multimeter on a current measuring range of a few hundred milliamps Connect the -VE supply rail to your power supply negative terminal and insert a multi-meter between the +13.8 VOLTS FOR RECEIVE PCB connection point and your power supply positive terminal, if everything is OK the measured current drawn in receive mode will be approximately 54mA's, this is the total current now being drawn by Q1 the RF Amplifier, Q2 the 1 st IF Amplifier, IC2 the 2nd IF amplifier and IC1/Q7 Audio output Stage.
If the current consumption test is OK it should be possible to hear a gentle hiss in the loudspeaker. Below is a chart showing the expected voltages present on the LM380-8 integrated circuit and Q7 2N3904 transistor, you can check these voltages against the chart and record your own readings for comparison and future test purposes. EXPECTED VOLTAGES FOR Q7 (2N3904) AUDIO OUTPUT DRIVER
Expected Voltage COLLECTOR
1.68
EMITTER
0
BASE
0.7
Own Measured Voltage Reading Log
EXPECTED VOLTAGES ON LM380-8 AUDIO OUTPUT IC PIN 1
0
PIN 2,4 & 5
Ground
PIN 3
0
PIN 6
6.17
PIN 7
12.57
PIN 8
6.35
PAGE 21
Next Stage Eleven
Stage Eleven – AGC & S-Meter Components list required for the AGC & S-Meter section: QUANTITY
VALUE
DESCRIPTION
CODE
1
100 OHM
0.25W Resistor
brn-blk-brn
4
10K
0.25W Resistor
brn-blk-ora
1
100K
0.25W Resistor
brn-blk-yell
2
150K
0.25W Resistor
brn-grn-yell
1
270K
0.25W Resistor
red-vio-yell
1
1M2
0.25W
brn-red-grn
3
50K
Preset
503
1
10K
Preset
103
1
5K
Preset
502
1
10NF (0.01uf)
Capacitor
103
3
1N4148
Silicon Diode
2
2.2UF 50Volt
Electrolytic Cap
1
47UF 50Volt
Electrolytic Cap
1
100UF 25Volt
Electrolytic Cap
1
LM324
Integrated Circuit
1
IC Socket
14 Pin DIL
FITTED
Using the photograph below as an illustration fit all parts listed in the stage eleven components list. Pay close attention to the orientation of the 1N4148 silicon diode, LM324 integrated circuit & all electrolytic capacitors.
PAGE 22
Continued
If you are using the 0.1 PCB connectors fit a 3 Pin & 2 of 2 Pin type to facilitate the connections of the AGC line to the 2 nd IF stage, AGC speed switch and S-Meter. if you are not using the 0.1 PCB connectors and hard wiring you can ignore these connection points for now. With all the components in place for stage eleven carry out the following checks to confirm the stage is working correctly:
DO NOT APPLY VOLTAGE TO THE RECEIVE AND TRANSMIT POINTS SIMULTANEOUSLY! Using a multimeter on a current measuring range of a few hundred milliamps Connect the -VE supply rail to your power supply negative terminal and insert a multi-meter between the ALL TIME +Ve PCB connection point and your power supply positive terminal, if everything is OK the measured current drawn in receive mode will be approximately 57mA's, this is the total current now being drawn by Q3 DDS/VFO amp, ADE-1 mixer number 1, Q5 & Q6 carrier oscillator/ buffer transistors and IC4 the AGC/S-Meter circuit.
EXPECTED VOLTAGES ON LM324 AGC IC PIN 4
13.25
PIN 11
Ground
The voltages on the other pins of the LM324 will be very much dependant on the alignment of the 47K pre-set connected to pin 3 of the LM324 via 150K resistor, referring to the layout photo on the previous page this is the bottom left pre-set. A preliminary adjustment of this pre-set can be made which will also help to confirm the AGC circuit is working and also set the threshold level. With your multimeter connected to PIN3 of LM324 adjust the 50K pre-set for a reading of 4 volts. The 10K pre-set will be adjusted later on in the alignment section.
PAGE 23
Next Stage Twelve
Stage Twelve – Microphone Pre-Amp Components list required for the Microphone Pre-Amp section: QUANTITY
VALUE
DESCRIPTION
CODE
1
100 OHM
0.25W Resistor
brn-blk-brn
3
10K
0.25W Resistor
brn-blk-ora
1
100K
0.25W Resistor
brn-blk-yell
1
1K
0.25W Resistor
brn-blk-red
1
50K
Preset
503
1
10NF (0.01uf)
Capacitor
103
1
100NF (0.1uf)
Capacitor
104
2
1UF 50Volt
Electrolytic Cap
1
10UF 50Volt
Electrolytic Cap
1
100UF 25Volt
Electrolytic Cap
1
NE5534
Integrated Circuit
1
IC Socket
8 Pin DIL
FITTED
Using the photograph below as an illustration fit all parts listed in the stage twelve components list. Pay close attention to the orientation of the NE5534 integrated circuit & all electrolytic capacitors.
There is actually a rogue resistor in this stage! The 220 OHM shown on the photo is a remnant from my experimenting and is not needed but you will need to fit a wire link in its place!
PAGE 24
Continued
The NE5534 Op-Amp IC is a low noise device but you can substitute this for any general purpose Op-Amp like the LM741. There is a 50K pre-set for adjusting the microphone gain of the Op-Amp but depending on your choice of microphone you may need to experiment with the gain of the Op-Amp by changing the value of the feedback control resistor 100K between pins 2 & 6. If you are using the 0.1 PCB connectors fit a 2 Pin type to facilitate the connections of the microphone. If you are not using the 0.1 PCB connectors and hard wiring you can ignore this connection point for now. With all the components in place for stage eleven carry out the following checks to confirm the stage is working correctly:
DO NOT APPLY VOLTAGE TO THE RECEIVE AND TRANSMIT POINTS SIMULTANEOUSLY! Using a multimeter on a current measuring range of a few hundred milliamps Connect the -VE supply rail to your power supply negative terminal and insert a multi-meter between the +13.8 VOLTS FOR TRANSMIT PCB connection point and your power supply positive terminal, if everything is OK the measured current drawn in transmit mode will be approximately 36 mA's, this is the total current now being drawn by Q10 RF Amplifier, Q9 2 nd IF Amplifier, Q8 1st IF Amplifier and IC3 Microphone Pre-Amplifier
Below is a chart showing the expected voltages present on the NE5534 integrated circuit, you can check these voltages against the chart and record your own readings for comparison and future test purposes. EXPECTED VOLTAGES FOR IC3 MICROPHONE PRE-AMPLIFIER
NOTE: Voltages measured with 50K gain pre-set in mid position Expected Voltage PIN 1
10.77
PIN 2
6.27
PIN 3
6.53
PIN 4
Ground
PIN 5
5.9
PIN 6
6.56
PIN 7
13.02
PAGE 25
Own Measured Voltage Reading Log
Next Stage Thirteen
Stage Thirteen – RF Driver Section Components list required for the RF Driver transmit section:
QUANTITY
VALUE
DESCRIPTION
CODE
1
10 OHM
0.25W Resistor
brn-blk-blk
2
100 OHM
0.25W Resistor
brn-blk-brn
1
1K
0.25W Resistor
brn-blk-red
1
2k2
0.25W Resistor
red-red-red
1
2N3904
NPN Transistor
4
100NF (0.1uf)
Capacitor
1
FT37-43
Amidon Toroid
FITTED
104
T2 transformer is made using an Amidon FT37-43 core. Wind 8 bifilar turns on the core using 0.28 (0.25 – 0.29mm will do) enamel covered copper wire as per the illustration:
The coil should take about 6 – 7 inches max of wire, 1 turn on the toroid is equal to 1 pass through the centre.
PAGE 26
Continued
Using the photograph below as an illustration fit all parts listed in the stage thirteen components list, Pay close attention to the orientation of the 2N3904 transistor.
If you are using the 0.1 PCB connectors fit 4 of the 2 Pin type to facilitate the connections of the Bandpass Filter, Receive Antenna Point, TX PA Module. If you are not using the 0.1 PCB connectors and hard wiring you can ignore this connection point for now. With all the components in place for stage Thirteen carry out the following checks to confirm the stage is working correctly:
DO NOT APPLY VOLTAGE TO THE RECEIVE AND TRANSMIT POINTS SIMULTANEOUSLY! Using a multimeter on a current measuring range of a few hundred milliamps Connect the -VE supply rail to your power supply negative terminal and insert a multi-meter between the +13.8 VOLTS FOR TRANSMIT PCB connection point and your power supply positive terminal, if everything is OK the measured current drawn in transmit mode will be approximately 65 mA's, this is the total current now being drawn by Q10 RF Amplifier, Q9 2 nd IF Amplifier, Q8 1st IF Amplifier, IC3 Microphone Pre-Amplifier and Q11 RF Amplifier.
PAGE 27
Continued
Below is a chart showing the expected voltages present on Q11 2N3904 , you can check these voltages against the chart and record your own readings for comparison and future test purposes.
EXPECTED VOLTAGES FOR Q11 (2N3904) RF AMPLIFIER
Expected Voltage COLLECTOR
10.55
EMITTER
2.53
BASE
3.23
PAGE 28
Own Measured Voltage Reading Log
Next Stage Fourteen
Stage Fourteen – IF Xtal Filter Section The BitX transceiver is usually constructed with a ladder type xtal filter using 10 or 11Mhz xtals but for convenience I built my prototype PCB with a xtal filter salvaged from a scrap CB Radio along with the 10.692Mhz carrier oscillator xtal, trimmer capacitors and the 4.7uh series inductor. The filter is usually found in the range of Ham International CB radios or those using the same chassis. The markings on the filter are “MCF SCM-107”. If you prefer to build the BitX multi-band with the standard ladder filter you can use my little addon PCB.
Crystal Filter Artwork G6LBQ 17/12/2010 PCB dimensions = 32MM by 20MM NOTE: Artwork looking at top of PCB or component side! A Ready Made PCB Is Available From Sunil Lakhani
[email protected] Artwork for the PCB is also available at the BitX Yahoo group in the “ Files” section under folder name “G6LBQ – Bitx”.
PAGE 29
Continued
The picture below shows a close up of the multi-band BitX with the ex CB Radio commercial filter fitted:
If you intend using the standard BitX ladder filter arrangement with the additional drop-in PCB you will have to remove the two 18PF capacitors as illustrated, these capacitors are only required for the commercial filter option.
This PCB is for the standard BITX ladder crystal filter comprising of 4 crystals and 3 capacitors, once constructed this PCB can be fitted to G6LBQ Multi band BitX in place of the commercial filter used.. The PCB is constructed as per my diagram below and drops straight into the multi-band PCB using stiff wire connections which form a PCB stand-off.
The PCB layout is not to scale and is for illustration only. The five green pads are the connection points made to multi-band BitX PCB using stiff wire stand-offs. These connection points line up with the crystal filter holes on multi-band Bitx board.
PAGE 30
Next wiring diagram
PCB Wiring Diagram
PAGE 31
Next schematic diagram
Schematic Diagram
PAGE 32
Next Alignment Details
Alignment of the Multiband BitX IF Section
The main receive section has only one adjustment which is the trimmer capacitor across IF coil T1, adjust for maximum signal, be careful not to adjust the IF so it becomes unstable, if you find a point when adjusting the trimmer that the MC1350 becomes unstable back the trimmer off a little. Carrier Oscillator (BFO)
The adjustment to the carrier oscillator frequency will depend on the choice of IF frequency selected. With a ladder filter arrangement the easiest way to align the oscillator is to tune to a known frequency/signal on another receiver/transceiver and make adjustments for both USB and LSB modes. If using the CB Radio type filter adjust for 10.692Mhz and 10.695Mhz. AGC Circuit
The AGC should have had a preliminary adjustment at the stage eleven testing stage (adjustment of 50K pre-set for 4 volts on pin3 of LM324)
Adjust the AGC gain to suit or set the pre-set as per the above image as a starting point and make fine adjustment if required. Microphone Gain
Adjust the 50K pre-set adjacent to the NE5534 Op-amp for a clean SSB signal.
PAGE 33
Continued
S-Meter Adjustment
There are two pre-set adjustments in the S-Meter circuit, the 5K pre-set is used to zero the meter whilst the 50K pre-set is used to adjust the meter level.
First of all make sure there is no antenna connected to the BitX and turn the 50K “Set Level” preset fully clockwise, now adjust the 5K “Set Zero” pre-set so the meter needle just reaches zero. The adjustment to set the S-meter level can now be performed by adjusting the 50K pre-set against a known signal using another receiver/transceiver or by using a signal generator and adjusting for an S9 signal with 50 microvolts input. NOTE
The S-Meter used is a 200uA type but there should be enough adjustment available for other signal level and VU meters
PAGE 34
Next full Bill Of Materials
G6LBQ MULTIBAND BITX BILL OF MATERIALS Last Updated On January 7th 2011 COMPONENT #
QTY
DESCRIPTION
DIODES
1
1N4148
10
General Purpose Silicon Diode
1 10
NPN Transistor Low Noise High Frequency RF Amp NPN Transistor TO92
1 1 1 1
8 Pin DIP Audio Amplifier 8 Pin DIP IF Amplifier With AGC 14 Pin DIP Quad Op Amplifier (AGC Control circuit) 8 Pin DIP Op Amplifier (Microphone Amp) Low Noise
2 2
MiniCircuits 6 Pin Frequency Mixer (Usually available on E-bay!) 6 Pin Turned Pin IC Sockets For Mounting ADE-1's
5 4 1 4 2
Radial Radial Radial Radial Radial
TRANSISTORS
1 2
2SC2570A 2N3904
INTERGRATED CIRCUITS
1 2 3 4
LM380-8 MC1350P LM324 NE5534
MIXER COMPONENTS
1 2
ADE-1 6 PIN IC Sockets
ELECTROLYTIC CAPACITORS
1 2 3 4 5
100UF 25 VOLT 47UF 25 or 35 VOLT 10UF 25 or 63 VOLT 1UF 50 or 63 VOLT 2.2UF 50 or 63 VOLT
Electrolytic Electrolytic Electrolytic Electrolytic Electrolytic
Capacitor Capacitor Capacitor Capacitor Capacitor
MULTILAYER CERAMIC CAPACITORS
1 2 3
100NF 50 VOLT 10NF 50 VOLT 10NF 63 VOLT
36 4 1
Multilayer Ceramic Capacitor 5mm 50 VOLT X7R Multilayer Ceramic Capacitor 5mm 50 VOLT X7R Polyester Film (Used for AGC Feed To LM324)
CERAMIC NPO CAPACITORS
1 2 3
18PF NPO 220PF NPO 100PF NPO
2 Ceramic NPO Capacitors Only Needed With CB Radio Xtal Filter 2 Ceramic NPO Capacitor 5mm 50/100 VOLT 1 Ceramic NPO Capacitor 5mm 50/100 VOLT TRIMMING CAPACITORS See additional construction notes regarding choice of trimmers, usage & alternatives with padding! 1 9 To 60PF 1 Murata Brown 5MM 9/60PF (Used to provide additional tuning to IF coil) 2 5.2 To 30PF 1 Murata Green 5MM 5.2/30PF (Used to tune Carrier Xtal) 3 4.2 To 20PF 1 Murata Red 5MM 4.2/20PF (Used to tune Carrier Xtal) TRIMMING POTENTIOMETERS
1 2 3
50k OR 47k Preset 10K Preset 4K7 or 5K Preset
3 1 1
6MM TruOhm Cermet Type or any with 5mm spaced pins 6MM TruOhm Cermet Type or any with 5mm spaced pins 6mm TruOhm Cermet Type or any with 5mm spaced pins
RESISTORS 0.25W
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
2R7 4R7 22R 10R 100R 220R 470R 1K 2K2 4K7 5K6 10K 15K 100K 120K 150K 270K 1M2
1 1 1 7 12 13 1 11 6 1 1 7 1 2 2 2 1 1
0.25W 0.25W 0.25W 0.25W 0.25W 0.25W 0.25W 0.25W 0.25W 0.25W 0.25W 0.25W 0.25W 0.25W 0.25W 0.25W 0.25W 0.25W
Axial Axial Axial Axial Axial Axial Axial Axial Axial Axial Axial Axial Axial Axial Axial Axial Axial Axial
Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor
CRYSTAL
1 2
Carrier Crystal Crystal Filter
1
10.692 MHZ Ex CB Radio SSB Carrier Crystal. See Notes For Alternative 10.695 MHZ Ex CB Radio SSB Crystal Filter. See Notes For Alternative
4.7uh Inductor IF Transformer FT37-43
1 1 1
RF inductor 4. 7uh (You may need to vary this value to pull carrier xtal) IF Transformer (Use old CB Radio IF can from 10.7 stage) or See Notes Amidon FT37-43 Core for winding PA driver transformer.
INDUCTORS
1 2 3
NYLON CONNECTORS & CRIMP PINS
1 2 3 4 5 6 7 8 9
2 PIN MALE 2 PIN FEMALE 3 PIN MALE 3 PIN FEMALE 4 PIN MALE 4 PIN FEMALE 5 PIN MALE 5 PIN FEMALE Crimp Pins
1
Main PCB
10 10 1 1 1 1 1 1 32
2 Pin PCB Male Connectors 0.1” Spacing With locking Ramp 2 Pin Female Connectors 0.1” Spacing With locking Ramp 3 Pin PCB Male Connectors 0.1” Spacing With locking Ramp 3 Pin Female Connectors 0.1” Spacing With locking Ramp 4 Pin PCB Male Connectors 0.1” Spacing With locking Ramp 4 Pin Female Connectors 0.1” Spacing With locking Ramp 5 Pin PCB Male Connectors 0.1” Spacing With locking Ramp 5 Pin Female Connectors 0.1” Spacing With locking Ramp Crimp Pins for The Female connectors
PCB
1
Main PCB Eit her Etc h or purchase from Sunil:
[email protected]
OPTIONAL LADDER XTAL FIL TER COMPONENTS
1
Xtals 10MHZ
4
2 3 4 5
Carrier Xtal 220PF NPO 100PF NPO Ladder Filter PCB
1 1 1 1
PAGE 35
Set of 4 matched xtals to form IF filter as oppose to CB style filter Please contact Sunil:
[email protected] for a matched set! Carrier crystal to suit IF crystal filter frequency. Ceramic NPO Capacitor 5mm 50/100 VOLT Ceramic NPO Capacitor 5mm 50/100 VOLT Optional PCB for Ladder Filter, drops straight into main PCB
Lastly a full page component layout
