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 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 Group BitX folder 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: vu3sua@gmail.com. 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 POWER 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 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 FITTED2 10 OHM 0.25W Resistor brn-blk-blk2 100 OHM 0.25W Resistor brn-blk-brn4 220 OHM 0.25W Resistor red-red-brn2 1K 0.25W Resistor brn-blk-red2 2K2 0.25W Resistor red-red-red9 100NF (0.1uf) Capacitor 1042 1N4148 Silicon Diode1 2N3904 NPN Transistor1 2SC2570A NPN Transistor1 4 Pin Male Con 0.1 Pitch Con

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 ANDTRANSMIT POINTS SIMULTANEOUSLY!

Using a multimeter on a current measuring range of a few hundred milliampsConnect 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 milliampsConnect 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 Own Measured Voltage Reading Log

COLLECTOR 8.76BASE 1.995EMITTER 2.711

EXPECTED VOLTAGES FOR Q10 (2N3904) TRANSMIT RF AMP STAGEExpected Voltage Own Measured Voltage Reading Log

COLLECTOR 8.69EMITTER 2.008BASE 2.703

PAGE 5 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 FITTED2 10 OHM 0.25W Resistor brn-blk-blk2 100 OHM 0.25W Resistor brn-blk-brn4 220 OHM 0.25W Resistor red-red-brn2 1K 0.25W Resistor brn-blk-red2 2K2 0.25W Resistor red-red-red8 100NF (0.1uf) Capacitor 1042 1N4148 Silicon Diode2 2N3904 NPN Transistor

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 ANDTRANSMIT POINTS SIMULTANEOUSLY!

Using a multimeter on a current measuring range of a few hundred milliampsConnect 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 1st 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 milliampsConnect 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 Own Measured Voltage Reading Log

EMITTER 1.99BASE 2.71COLLECTOR 8.74

EXPECTED VOLTAGES FOR Q9 (2N3904) TRANSMIT 2ND IF STAGEExpected Voltage Own Measured Voltage Reading Log

EMITTER 1.97BASE 2.7COLLECTOR 8.76

PAGE 7 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 FITTED1 10 OHM 0.25W Resistor brn-blk-blk1 100 OHM 0.25W Resistor brn-blk-brn2 1K 0.25W Resistor brn-blk-red2 100NF (0.1uf) Capacitor 1041 2N3904 NPN Transistor

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 – 1st Mixer Section

Components list required for the 1st Mixer section:

QUANTITY VALUE DESCRIPTION CODE FITTED1 100 OHM 0.25W Resistor brn-blk-brn1 100NF (0.1uf) Capacitor 1041 ADE-1 Mixer1 IC Socket Turned Pin Skt

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 cut 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 ANDTRANSMIT 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 milliampsConnect 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 ADE-1 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 Own Measured Voltage Reading Log

COLLECTOR 9.27EMITTER 3.78BASE 4.5

EXPECTED VOLTAGES FOR ADE-1 MIXER STAGE 1Expected Voltage Own Measured Voltage Reading Log

PIN 1 9.26PIN 6 9.26PINS 2,3,4,5 0 Volts

PAGE 11 Next Stage Six

Stage SIX – 2ND IF Amplifier Receive Section

Components list required for the 2nd IF amplifier receive section:

QUANTITY VALUE DESCRIPTION CODE FITTED1 100 OHM 0.25W Resistor brn-blk-brn1 220 OHM 0.25W Resistor red-red-brn1 15K 0.25W Resistor brn-green-orange2 10NF (0.01uf) Capacitor 1033 100NF (0.1uf) Capacitor 1041 MC1350P Integrated Circuit1 IC Holder 8 Pin 8 Pin DIL1 1N4148 Silicon Diode1 60PF (optional) Murata Trimmer 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 ANDTRANSMIT POINTS SIMULTANEOUSLY!

Using a multimeter on a current measuring range of a few hundred milliampsConnect 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 1st IF Amplifier and the completed stage six 2nd 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 Own Measured Voltage Reading Log

PIN 1 & 2 11.3PIN 3 & 7 GroundPIN 4 3.86PIN 5 5.65PIN 6 3.86PIN 8 11.3

PAGE 13 Next Stage Seven

Stage Seven – 1ST IF Amplifier Transmit Section

Components list required for the 1st IF amplifier transmit section:

QUANTITY VALUE DESCRIPTION CODE FITTED1 4.7 OHM 0.25W Resistor yell-violet-gold1 100 OHM 0.25W Resistor brn-blk-brn1 220 OHM 0.25W Resistor red-red-brn1 470 OHM 0.25W Resistor yell-violet-brown1 1K Capacitor brn-blk-red1 2K2 Capacitor red-red-red4 100NF (0.1uf) Capacitor 1041 1N4148 Silicon Diode1 2N3904 NPN Transistor

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 ANDTRANSMIT POINTS SIMULTANEOUSLY!

Using a multimeter on a current measuring range of a few hundred milliampsConnect 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 2nd 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 Own Measured Voltage Reading Log

COLLECTOR 10.1EMITTER 2.4BASE 3.1

PAGE 15 Next Stage Eight

Stage Eight – 2ND Mixer Section

Components list required for the 2nd Mixer section:

QUANTITY VALUE DESCRIPTION CODE FITTED1 ADE-1 Mixer1 22 OHM 0.25W Resistor red-red-blk2 220 OHM 0.25W Resistor red-red-brown1 IC Socket Turned Pin Skt

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 FITTED1 100 OHM 0.25W Resistor brn-blk-brn3 1K 0.25W Resistor brn-blk-red1 5K6 0.25W Resistor grn-blu-red1 120K 0.25W Resistor brn-red-yell3 2N3904 NPN Transistor1 Carrier Xtal Freq To Suit IF1 4.7uh Inductor1 22PF Murata Trimmer Red1 30PF Murata Trimmer Green2 220PF NP0 Capacitor 2212 100NF (0.1uf) Capacitor 1041 10NF (0.01uf) Capacitor 1032 47UF 50Volt Electrolytic Cap1 78L09 Regulator

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 2nd 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 ANDTRANSMIT POINTS SIMULTANEOUSLY!

Using a multimeter on a current measuring range of a few hundred milliampsConnect 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 REGULATORExpected Voltage Own Measured Voltage Reading Log

OUTPUT PIN 8.9

EXPECTED VOLTAGES FOR Q5 (2N3904) OSCILLATORExpected Voltage Own Measured Voltage Reading Log

COLLECTOR 8.07EMITTER 4.3BASE 4.6

EXPECTED VOLTAGES FOR Q6 (2N3904) OSCILLATOR BUFFER STAGEExpected Voltage Own Measured Voltage Reading Log

COLLECTOR 8.07EMITTER 3.9BASE 4.29

EXPECTED VOLTAGES FOR Q4 (2N3904) USB/LSB SWITCHExpected Voltage Own Measured Voltage Reading Log

COLLECTOR 0 Volts or millivolts. Later when the USB/LSB switch is fitted voltages will depend on switch position!

EMITTERBASE

PAGE 19 Next Stage Ten

Stage Ten – Audio Output Amplifier

Components list required for the audio output section:

QUANTITY VALUE DESCRIPTION CODE FITTED1 2R7 OHM 0.25W Resistor red-vio-gold1 10 OHM 0.25W Resistor brn-blk-blk1 220 OHM 0.25W Resistor red-red-brn1 4k7 0.25W Resistor yell-vio-red1 120K 0.25W Resistor brn-red-yell3 100uf 25Volt Electrolytic Cap1 47uf 50Volt Electrolytic Cap2 1uf 50Volt Electrolytic Cap2 100NF (0.1uf) Capacitor 1041 1N4148 Silicon Diode1 2N3904 NPN Transistor1 LM380-8 Integrated Circuit1 IC Socket 8 Pin DIL2 47UF 50Volt Electrolytic Cap1 78L09 Regulator1 4k7 Potentiometer

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 ANDTRANSMIT POINTS SIMULTANEOUSLY!

Using a multimeter on a current measuring range of a few hundred milliampsConnect 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 1st 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 Own Measured Voltage Reading Log

COLLECTOR 1.68EMITTER 0BASE 0.7

EXPECTED VOLTAGES ON LM380-8 AUDIO OUTPUT ICPIN 1 0PIN 2,4 & 5 GroundPIN 3 0PIN 6 6.17PIN 7 12.57PIN 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 FITTED1 100 OHM 0.25W Resistor brn-blk-brn4 10K 0.25W Resistor brn-blk-ora1 100K 0.25W Resistor brn-blk-yell2 150K 0.25W Resistor brn-grn-yell1 270K 0.25W Resistor red-vio-yell1 1M2 0.25W brn-red-grn3 50K Preset 5031 10K Preset 1031 5K Preset 5021 10NF (0.01uf) Capacitor 1033 1N4148 Silicon Diode2 2.2UF 50Volt Electrolytic Cap1 47UF 50Volt Electrolytic Cap1 100UF 25Volt Electrolytic Cap1 LM324 Integrated Circuit1 IC Socket 14 Pin DIL

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 2nd 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 ANDTRANSMIT POINTS SIMULTANEOUSLY!

Using a multimeter on a current measuring range of a few hundred milliampsConnect 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 ICPIN 4 13.25PIN 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 FITTED1 100 OHM 0.25W Resistor brn-blk-brn3 10K 0.25W Resistor brn-blk-ora1 100K 0.25W Resistor brn-blk-yell1 1K 0.25W Resistor brn-blk-red1 50K Preset 5031 10NF (0.01uf) Capacitor 1031 100NF (0.1uf) Capacitor 1042 1UF 50Volt Electrolytic Cap1 10UF 50Volt Electrolytic Cap1 100UF 25Volt Electrolytic Cap1 NE5534 Integrated Circuit1 IC Socket 8 Pin DIL

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 ANDTRANSMIT POINTS SIMULTANEOUSLY!

Using a multimeter on a current measuring range of a few hundred milliampsConnect 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 2nd 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 Own Measured Voltage Reading LogPIN 1 10.77PIN 2 6.27PIN 3 6.53PIN 4 GroundPIN 5 5.9PIN 6 6.56PIN 7 13.02

PAGE 25 Next Stage Thirteen

Stage Thirteen – RF Driver Section

Components list required for the RF Driver transmit section:

QUANTITY VALUE DESCRIPTION CODE FITTED1 10 OHM 0.25W Resistor brn-blk-blk2 100 OHM 0.25W Resistor brn-blk-brn1 1K 0.25W Resistor brn-blk-red1 2k2 0.25W Resistor red-red-red1 2N3904 NPN Transistor4 100NF (0.1uf) Capacitor 1041 FT37-43 Amidon Toroid

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 ANDTRANSMIT POINTS SIMULTANEOUSLY!

Using a multimeter on a current measuring range of a few hundred milliampsConnect 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 2nd 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 Own Measured Voltage Reading Log

COLLECTOR 10.55EMITTER 2.53BASE 3.23

PAGE 28 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 add-on 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 vu3sua@gmail.com

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” pre-set 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.

NOTEThe 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

PAGE 35 Lastly a full page component layout

G6LBQ MULTIBAND BITX BILL OF MATERIALS# COMPONENT QTY DESCRIPTION

DIODES1 1N4148 10 General Purpose Silicon Diode

TRANSISTORS1 2SC2570A 1 NPN Transistor Low Noise High Frequency RF Amp2 2N3904 10 NPN Transistor TO92

INTERGRATED CIRCUITS1 LM380-8 1 8 Pin DIP Audio Amplifier2 MC1350P 1 8 Pin DIP IF Amplifier With AGC3 LM324 1 14 Pin DIP Quad Op Amplifier (AGC Control circuit)4 NE5534 1 8 Pin DIP Op Amplifier (Microphone Amp) Low Noise

MIXER COMPONENTS1 ADE-1 22 6 PIN IC Sockets 2 6 Pin Turned Pin IC Sockets For Mounting ADE-1's

ELECTROLYTIC CAPACITORS1 100UF 25 VOLT 5 Radial Electrolytic Capacitor2 47UF 25 or 35 VOLT 4 Radial Electrolytic Capacitor3 10UF 25 or 63 VOLT 1 Radial Electrolytic Capacitor4 1UF 50 or 63 VOLT 4 Radial Electrolytic Capacitor5 2.2UF 50 or 63 VOLT 2 Radial Electrolytic Capacitor

MULTILAYER CERAMIC CAPACITORS1 100NF 50 VOLT 36 Multilayer Ceramic Capacitor 5mm 50 VOLT X7R2 10NF 50 VOLT 4 Multilayer Ceramic Capacitor 5mm 50 VOLT X7R3 10NF 63 VOLT 1 Polyester Film (Used for AGC Feed To LM324)

CERAMIC NPO CAPACITORS1 18PF NPO 22 220PF NPO 2 Ceramic NPO Capacitor 5mm 50/100 VOLT3 100PF NPO 1 Ceramic NPO Capacitor 5mm 50/100 VOLT

1 9 To 60PF 12 5.2 To 30PF 13 4.2 To 20PF 1

TRIMMING POTENTIOMETERS1 32 13 1

RESISTORS 0.25W1 2R7 1 0.25W Axial Resistor2 4R7 1 0.25W Axial Resistor3 22R 1 0.25W Axial Resistor4 10R 7 0.25W Axial Resistor5 100R 12 0.25W Axial Resistor6 220R 13 0.25W Axial Resistor7 470R 1 0.25W Axial Resistor8 1K 11 0.25W Axial Resistor9 2K2 6 0.25W Axial Resistor10 4K7 1 0.25W Axial Resistor11 5K6 1 0.25W Axial Resistor12 10K 7 0.25W Axial Resistor13 15K 1 0.25W Axial Resistor14 100K 2 0.25W Axial Resistor15 120K 2 0.25W Axial Resistor16 150K 2 0.25W Axial Resistor17 270K 1 0.25W Axial Resistor18 1M2 1 0.25W Axial Resistor

CRYSTAL1 Carrier Crystal 1 10.692 MHZ Ex CB Radio SSB Carrier Crystal. See Notes For Alternative2 Crystal Filter 10.695 MHZ Ex CB Radio SSB Crystal Filter. See Notes For Alternative

INDUCTORS1 12 IF Transformer 1 IF Transformer (Use old CB Radio IF can from 10.7 stage) or See Notes3 FT37-43 1

NYLON CONNECTORS & CRIMP PINS1 2 PIN MALE 10 2 Pin PCB Male Connectors 0.1” Spacing With locking Ramp2 2 PIN FEMALE 10 2 Pin Female Connectors 0.1” Spacing With locking Ramp3 3 PIN MALE 1 3 Pin PCB Male Connectors 0.1” Spacing With locking Ramp4 3 PIN FEMALE 1 3 Pin Female Connectors 0.1” Spacing With locking Ramp5 4 PIN MALE 1 4 Pin PCB Male Connectors 0.1” Spacing With locking Ramp6 4 PIN FEMALE 1 4 Pin Female Connectors 0.1” Spacing With locking Ramp7 5 PIN MALE 1 5 Pin PCB Male Connectors 0.1” Spacing With locking Ramp8 5 PIN FEMALE 1 5 Pin Female Connectors 0.1” Spacing With locking Ramp9 Crimp Pins 32 Crimp Pins for The Female connectors

PCB 1 Main PCB 1

OPTIONAL LADDER XTAL FILTER COMPONENTS1 4

2 1 Carrier crystal to suit IF crystal filter frequency.3 220PF NPO 1 Ceramic NPO Capacitor 5mm 50/100 VOLT4 100PF NPO 1 Ceramic NPO Capacitor 5mm 50/100 VOLT5 Ladder Filter PCB 1 Optional PCB for Ladder Filter, drops straight into main PCB

Last Updated On January 7th 2011

MiniCircuits 6 Pin Frequency Mixer (Usually available on E-bay!)

Ceramic NPO Capacitors Only Needed With CB Radio Xtal Filter

TRIMMING CAPACITORS See additional construction notes regarding choice of trimmers, usage & alternatives with padding! Murata Brown 5MM 9/60PF (Used to provide additional tuning to IF coil)Murata Green 5MM 5.2/30PF (Used to tune Carrier Xtal)Murata Red 5MM 4.2/20PF (Used to tune Carrier Xtal)

50k OR 47k Preset 6MM TruOhm Cermet Type or any with 5mm spaced pins10K Preset 6MM TruOhm Cermet Type or any with 5mm spaced pins4K7 or 5K Preset 6mm TruOhm Cermet Type or any with 5mm spaced pins

4.7uh Inductor RF inductor 4.7uh (You may need to vary this value to pull carrier xtal)

Amidon FT37-43 Core for winding PA driver transformer.

Main PCB Either Etch or purchase from Sunil: vu3sua@gmail.com

Xtals 10MHZ Set of 4 matched xtals to form IF filter as oppose to CB style filterPlease contact Sunil: vu3sua@gmail.com for a matched set!

Carrier Xtal