The Radio-Kits “Hunter”
Contents
1. 3 4 door 10v R38 RAT d cs 2 4 ET te R31 1 810 R51 4 ms 4 5 a 3 4 m gt BN2402 42 3 35 e N Raz aw e 10V Line out A I 2 Our uF 10V R43 te R44 569 I duF csa aso Fo Rag 1 1 FS 7974 TS Mae Ves 2 13 tivro 1D zcr 3 12 m ack rs D eee Tek 12 5 20 Ond 170 l T whe 629 Not fitted ge 53 Q luF t R23 U2 MCP1824T ADJE DC t 1 R18 R24 N ik 47k 2 I E x 45 T T 7 N Le E UE UE UE 4 7uF 16V Ceranic a a m m us 1702 TAS 3 Vin Vout Gnd EP C24 1 1 1 Rapid 26 2556 ut ATmegaBA 16PU2. 815 R19 Bieri R13 R12 1 28 100R 1008 1808 BED D 262 1M Pce pos ne 2 27 PC 5 3 26 R5 68R NC PD1 PC 3 2 B B 4 25 02 Poa eU NC 1 ai D 23 5 No PD4 on 1 C43 c28 Gnd SU s 21 1uF QUE aur cm Lepr NC avec 10 19 R27 C23 a 7 m Not fitted jj IPDS PB 1 2 KR Tr 12 17 Pes Pea 2 4 z R34 R37 PD7 2 NC E 346 m D4 c25 4 NC PBO PB1 NC NC Ve BZXB4 C3V6 2 D3 SDA Cle BZX84 3 6 7 SKT7 6 pin header R33 R32 Programming socket SCL Cik 5 68R 6ER UA E Siszx PCB overlay 480005 ZY Change Log Version hangs atte changes made 8 09 11 9 09 11
3. NES NEU NES ENS eee BAP64 05 or BAP65 05 Marked 5 or 7KW NEM NES NEN MU S ee ee NNNM 0 1uF DOM EUR NU EINER NEUEN ft ft ft _ ENDO Ee Version R1 1 From bag 5 fit the following From bag 7 fit the following 100k Marked TOT or 1000 The fuse looks similar to a resistor white marking on a black surface DE RIN RIA RIST RIO but is in a slightly larger package 1206 Ensure this component is in RO 2 the correct place before soldering as it will be destroyed if you attempt R28 ES R50 to move it 200mA 1206 Fuse Marked C _ E BC847B Marked 1FN 240R Marked 241 or 2400 _ L4 L10 Li rj ENG NNUS From bag 6 fit the following Ik Marked 102 or 1001 o R8 Ri R2 R 3 lt i ______ luF emp MNE 68 From bag 8 fit the following I Hl I et 011 a RK Hunter Construction manual 6 Version R1 1 From bag 9 fit the following 2k2 Marked 222 or 2201 NEN 390pF C38 6 From bag 10 fit the following 10k Marked 103 1002 R16 R17 R23 R40 R41 820pF cs9 64 From bag 11 f
4. After the USB socket has been soldered in place carefully cut the outside retaining tag as short as possible this is to avoid it shorting to the case once the PCB is slid into place USB type B socket L SKTI 3 5mm Jack socket SKT2 SKT3 77 N gt 2 c gt 2 Red LED 2 Pole push switch SWI SW2 pe zi B zeg u 5 65 o gt o d 9 Hm 55 EB ga 29 e gt gt eR c e S 5 e e E 5 a oy gt 25 ge 8 9 O 5 Q E e E B C w 16MHz Crystal XTALI 1 oo 1 RK Hunter Construction manual Version R1 1 Winding T1 T1 uses balun core and has a 5 turn primary winding with a bifilar wound 3 turn secondary Cut a piece of 36 SWG enamelled copper wire about 30cm long and fold it in half squeeze the loop at the fold so it is more suitable for passing through the core Thread the wire through one of the holes in the core leaving about 5cm of wire remaining then thread the long length through the other hole this is one complete turn Wind another 2 complete turns through the core making a total of 3 Cut another piece of 36 SWG wire about 20cm long but do not fold it Pass the wire into the core
5. on the PC audio interface Connect the SO239 ant connector on Hunter to your antenna or if used the transceiver input on an ATU if using as a panoramic adapter to a transceiver connect Trx on Hunter to the transceiver antenna socket Version R1 1 Hunter has provision for the antenna change over relay to be switched via a transceiver PTT input if this facility is used Hunter will automatically switch to the transceiver as soon as the PTT is pressed To make use of this feature a lead is required fitted with a 3 5mm jack plug stereo or mono Hunter end and on the other end a suitable connector for the transceiver For the transceiver to follow the frequency tuned by Hunter CAT control will also need to be set up between the transceiver and PC integration between CAT and HDSDR is by a program called Omnirig which is free ware With software General use 5570 LO Tune ABPF Calibrate Test Int Te correctly installed Genera and running Hunter SoftRock Configuration tool should be identified Powered by Si570 as a USB device Manufacturer www obdev at This can be confirmed by clicking on the small ExtIO icon from within HDSDR this will Green light indicates activate the e hunter is connected PEOFKO Softrock Configuration tool In the bottom left hand corner is an activity indicator which will turn green if Hunter has been identified Product DG8SAQ I2C Serial number G6ALU 1 0 U
6. MHz There are two tables provided one in SDR mode and the other with the SDR TRX switch depressed It is possible for the EEPROM data 5670 within the microcontroller to become corrupted this can lead to wrong or no control of the 51570 device Use the Softrock Configuration tool to return to the Press H to show when hidden Close default settings Select the 1570 tab and click on the Factory default button calibration data will be wiped so Calibrate A will need to be repeated General USB 5570 10 Tune Calibrate Test Mot T 2 addr 0x55 hex Save Freq range 1 160 Startup 28 200001 MHz FO 7 0500003 Save Smooth 3500 ppm VFO 24 7 KHz Save 5 570 DCOmin _ DCO Reset 5570 Factory default If the microcontroller is inadvertently initialised using the Init tab within the Softrock Configuration tool then inappropriate BPF frequency settings will be applied to correct this go to the Mobo tab and enter the following frequencies into the TX filter window Hunter uses the TX filter output to control the BPF Version R1 1 Frequency Filter 0 2 0 2 4 1 4 8 2 8 15 3 15 30 4 30 oo 5 Safety considerations PME systems In the UK many domestic dwellings are now wired with a PME protected multiple earth system Hunter is likely to be earthed via the mains outlet by the PC as will any mains powere
7. from the other side and wind on 5 complete turns this will result in a transformer with 4 wires coming out of one side and 2 from the other similar to the photo Trim the 2 wires to about 2 cm and tin along their length with a hot iron and solder If hot enough the molten solder will break down the enamel and tin the copper beneath if your iron isn t hot enough it may be necessary to scrape the wire prior to tinning experiment with a spare piece first RK Hunter Construction manual 9 5 Turn secondary Trim the remaining 4 wires to about 4 cm long and tin just the end of the wire Using a multimeter set to read continuity identify the start and end of each wire we will call one wire A and the other wire Twist the end of wire A with the start of wire B which will form a centre tap Tin the three wires one being two twisted together then confirm continuity between all three wires with a multimeter Install the transformer into the PCB the core may touch the PCB and can be secured with silicon adhesive nail varnish or a very small drop of hot melt glue once the complete receiver is tested BN43 2402 core Primary 5T secondary 3 3T bifilar wound using 36 SWG ECW ENG ae Test for short circuits on input With a digital meter switched to the resistance range measure between one end of F1 1 amp axial fuse and ground the ground connection can be taken from the USB
8. to turn this causes an indent in the plastic which helps to locate the drill bit RK Hunter Construction manual 11 With a large drill bit carefully countersink the holes for the 50239 mounting screws from the outside of the end plate use a screw to judge the correct depth To cut the square hole for the USB socket first drill a series of small holes and then join with a modelling knife take care not to cut yourself with the sharp knife Trial fit the front and rear panels if all is OK permanently fit the front panel to the aluminium extrusion as the front panel decal covers the fixing screws access for maintenance can be made by removing the rear panel screws From the Radio Kits website download and print the front and rear panel decals remember to print with scaling set to none Cover with plastic film and use double side adhesive tape to fix to the panels Note that large holes have been made for the line out and PTT sockets this is to allow the plug to fit right down to the panel Version R1 1 Assemble the connector PCB to rear panel wm oN Cut out in inner JI contact upper most Pass the two SO239 sockets through from the inside and securing with 8 countersunk screws 4 shake proof washers and nuts Note that two terminal tags fit under the the lower outer nuts these are used to make a ground connection to the main
9. PCB Fit the connectors so the cut Solder tags positioned under lower outer nuts out in the centre pin is uppermost The connector PCB assembly can now be fitted to the main PCB first cut and solder pieces of 20SWG tinned copper wire through the ANT and TRX connector holes so there is about 15mm of wire protruding from the top of the PCB crop the wire under the board so it wont short to the case Slide the main PCB into the lower slot of the case extrusion then fit the connector assembly and hold in place with four black screws provided Check to make sure the PCB isn t protruding through the front of the extrusion if it is check that the pips have been removed from the break off areas of the PCB Bend then solder the ANT and TRX wires to the inner SO239 pins cropping the wire as necessary RK Hunter Construction manual 12 Cut two more short pieces of tinned copper wire and solder between the earth tags and ground pads provided on the PCB Commissioning To test the radio its first necessary to install the software if not already installed follow the instructions appropriate for your operating system they can be found in a separate document on the Radio Kits website Connect up Hunter to PC and the transceiver Connect the SDR to PC with USB lead and use an audio lead fitted with 3 5mm stereo jacks to connect between Line out on Hunter and Line in
10. SB AVR Si570 connected V16 2 An unused microcontroller will need to interrogate 51570 to calculate the internal crystal frequency to do this switch to the Calibrate tab and under the heading Calibrate A click the calibrate button Note that the crystal frequency is different for every 51570 RK Hunter Construction manual 13 General USB 5570 LO Calibrate Calibrate by using the factory default startup frequency You will need the 5570 device startup the chip is factory 1 5ppm on that frequency Factory startup frequency 56 32 Calibpat Calibrate by tune on a carier with a know frequency and enter the real frequency I This calibration should result in an initial frequency accuracy within 1 5ppm but can be adjusted later using Calibrate B with reference To reset the calibration to factory default press Reset Tuned Real to known signal Frequency 7 159133 7159133 0 0KHz source WWV Crystal frequency et 114 250800 MHz Press H to show when hidden Check the function of antenna switching circuit Connect an SWR or power meter to the Ant connector and terminate this with a dummy load Connect a HF transceiver to the TRX connector and power Hunter via a PC Tune the transceiver to the 10M band and using low power 1 5 Watts confirm Hunter senses the RF and swi
11. The Radio Kits Hunter SDR receiver and Panadapter Construction and user manual Author Steve Drury GGALU List of contents Section Page no 1 Features 2 2 Specifications 2 3 Introduction 2 4 Construction 3 5 General construction practice 3 6 Soldering 3 7 Component identification 3 8 Component placement 4 9 Assembling to case 11 10 Commissioning 12 11 In use 14 12 Fault finding 14 13 Safety considerations 15 14 Circuit description 15 15 Voltage tables 17 16 Circuit diagram 18 20 17 PCB overlay 21 18 Change log 22 RK Hunter Construction manual 1 Version R1 1 Features Monitors a wide frequency span e Adds a Panadapter function to a commercial transceiver without internal modification e Tunes transceiver to selected frequency via CAT control Powered from USB includes a high quality PCB all components case and solder Typical Specifications Operating Frequency 2 5 30MHz Single tone dynamic range gt 110dB dynamic range Sensitivity Noise floor 137dBm Maximum power handling 120W 1 Transceiver requires CAT control from PC 2 Determined by lower frequency of 51570 1 30MHz typically 3 Parameters dependent on sound card specifications RK Hunter Construction manual 2 Introduction RK Hunter is a HF band SDR receiver based on the now classic QSD quadrature sampling detector technology first introduced to the amateur community by Gerald Yo
12. at single pad If all the pins aren t perfectly aligned with the pads then reheat the joint and realign the chip when you are happy that the alignment is correct solder all pins RK Hunter Construction manual ius From Bagl fit the following Note solder tabs of U2 and U3 to PCB MCP1824T Marked 1824ADJ _______________ MCP1702T Marked HG C43 C36 Tym 4 2 cas R33 R34 Note orientation of text 5 R39 f Dot indicates Ree R41 C60 U6 pin 1 end Pin 1 of US isn t explicitly marked if you look VERY carefully one side of the device has a larger chamfer than the other this is pin 1 side It may be easier to use the photo as reference taking note of the orientation of the writing on the chip Version R1 1 LT6231 Marked 6231 05 Pin 1 of U6 is marked with a dot T4VHC74 Marked 74VHC74 U6 Pin one end of U7 is identified with a printed bar note this IC is mounted in the opposite direction to US SN74CBT3253 Marked CBT3253C _ From bag 2 fit the following 47k Marked 4702 or 473 R10 R24 10nF OR eae wee aes eee rE eT ft Ht HoH Se eed cis BZX84 C3V6 Marked WB2 D i D4 From bag 3 fit the following RK Hunter Construction manual 82pF NEN NENNEN S BAV99 Marked A7 NES NEN ee eS D10 12 From bag 4 fit the following
13. d transceiver and in the event of a neutral conductor failure at the substation could cause an electric shock hazard Precautions needed will be dependent on house and shack wiring you are referred to the RSGB publication RSGB guide to EMC and the IEE wiring regulations Transceiver to PC ground loop With the transceiver connected to mains power via an earthed power supply there is a risk that if the V negative lead of the transceiver becomes disconnected then the full supply current will flow down the USB and audio leads into the PC Currents as high as 25 Amps could flow leading to damage within the PC this occurs because the power supply Ve is connected to earth and both PC and power supply are connected by the earth conductor of the mains wiring Hunter has weak points designed in its grounding to try and limit any current flow from damaging the PC but it is very important that the transceiver Ve lead is never allowed to become disconnected during operation RK Hunter Construction manual 15 USB supply protection Some PCs don t have any protection in the USB 5V supply with these PCs if a short circuit in the USB output occurs damage to the circuitry will result F1 1 amp QB fuse has been incorporated to mitigate this but caution should still be observed to avoid shorts on the Hunter PCB Circuit description Refer to schematics for component references The signal first passes through the antenna relay this i
14. e leakage to below 50dBm RK Hunter Construction manual 16 C49 and 50 are the hold capacitors their value partly determines the bandwidth of receive signals U5 is a very low noise op amp which amplifies the relatively low amplitude signal before passing to the sound card via the socket Skt2 C44 and C45 form a low pass filter for I and Q channels Communication between Hunter and the PC USB interface is provided by an Atmel processor the processor controls the 51570 and also controls BPF selection from port pins PCO PC4 The programme is written in and is based on firmware originally written by DG8SAQ heavily modified by PEOFKO and TF3LJ then modified for this application by me G6ALU source code will be made available on the Radio Kits website Provision has been made for Skt7 for programming the AVR micro for those wishing to make changes to the code Most circuits run from a 4 6V supply generated from the USB 5V supply by U2 a low drop out adjustable regulator this is required as the PC s 5V supply is very noisy which manifests itself as unwanted signals in the received waveform mostly around the 0Hz point centre of screen A 3 3 Volt supply for the S1570 is provided by U3 a fixed voltage regulator A amp wire ended fuse F1 has been fitted in the USB 5V supply some PCs aren t protected against short circuits to the USB supply this fuse has been incorporated chance of damage in the instance of a shor
15. it the following R20 R26 56 1500pF C66 From bag 12 fit the following 10R Marked 100 10RO EN ESO NNUS SSeS ors See __ 2700 ee Ee MM RK Hunter Construction manual From bag 13 fit the following 3k3 Marked 332 or 3301 NEN 220pF NEN From bag 14 fit the following 4k7 Marked 472 or 4701 if Ff E 680pF C47 From bag 15 fit the following a 22R Marked 220 2280 NEN 1200pF C58 The following surface mount components aren t fitted check that nothing has accidentally been placed in their positions C27 C29 R2 R21 R25 R27 The only other SMT position vacant should be for U4 Si570 From bag 16 fit the following through hole components note that all of these parts are fitted from the top side of the PCB Some component pins may have become bent during packing please inspect and straighten before fitting Version R1 1 220UF 10V ci 11 Fit the 28 pin IC socket so the notch matches the notch position marked on the PCB 4TUF 10V Ey hee 1A wire ended fuse Marked 1A Bend the LED legs about 10mm from Relay Marked G5V 2 5DC the body and solder into PCB so the LED centre line is the same as the switches The anode lead is the longest of the two RLYI
16. n and possible damage to the relay contacts RF power has to be present before the relay is switched so hot switching is inevitable Version R1 1 Construction General construction practice Components are taken from one bag at a time keeping the others sealed Each bag contains several types of component this may be unconventional but it reduces the number of bags whilst stopping components getting confused Tick the check box as each instruction is completed or component fitted Preparing the PCB Break off the bridges at points shown red and remove pips left behind The two sections of PCB were manufactured as one part with bridges between These need separating by breaking in two this RK Hunter Construction manual 3 will leave little pips along the front edge Remove the the pips with a sharp knife or file if left in place the two PCBs won t assemble into the case correctly Soldering A generous quantity of thin 0 46mm SMT rework solder has been supplied for use with the surface mount components this contains lead which contrary to popular belief is not illegal for your own use As always when using solder don t breathe the fumes the flux can cause problems for those with respiratory conditions For through hole components you can use standard solder 0 7mm 60 40 tin lead is recommended If you use a temperature controlled iron ensure that it is hot enough a temperat
17. ng before they are detected as a wanted signal Following the LPF is a manually switched attenuator with values selected for about 20dB this can be switched in circuit when required to attenuate large signals It is important not to let the PC sound card AD converter saturate as significant degradation in signal quality will result Hunter is based on the classic QSD quadrature sampling detector where a block of frequencies are down converted to audio for processing by a PC The QSD circuit requires a two phase oscillator two signals 90 out of phase at the signal frequency In Hunter this is achieved with an S1570 programmable oscillator U4 running at 4 x the desired receive frequency this is divided by 4 with dual D type latches U7 interconnected so that 4 signals are developed each 90 out of phase with each other Only two of these signals are used as the inverted form is generated by the phase splitting action of T1 supplying the QSD with two signals 180 out of phase Before the signal is passed to the QSD it is buffered and amplified by common Source FET amplifier Q5 the importance of this amplifier is to provide isolation between the QSD and antenna The QSD is driven by an oscillator at signal frequency which cannot then be filtered by the low pass filter without the buffer amplifier significant oscillator leakage will get to the antenna and potentially cause interference to other band users The FET amplifier reduces th
18. r R21 Nat Fitted Bcss7E 2 Fin header Re ik RI 15k ROS Not titted ES RLY1 c D a psy 25pc B V93 G2pF 100v Ra Nat Fitted BKTS cio SKT S Antenna 7 47k SKT3 cs i nF PTT BPF n Diets as mj C44 220 Rap len pi E Bibi as en nea BAP 65 06 5 d Di4 a 1880 Na 15 99MHz 5 05 BPF 15 0 olo ojo E F s C55 6 4 3 1 BiuF d 223 RSS E i cai R53 R54 BER 15 24 4 15 3 di See She 46 Has ri Dist s 20dB Attenuator Li d I e wR m oc 0126 Le cse E 22 nee BIER ae L4 NPO 4 E NFO bat 4 ite alae 4 FS2 850 1008 100R C65 r Site Ber anne 4 4 4 Cs 15 iSG pF NPO 2 4M4z 150apF NPA 22uH 016 5 pom Sew LAL EET 258 1266pF NPA FY 2 serian Dita C20 css Sur D
19. s either switched by the transceiver PTT output RF sensed or manually by SWI RF from the transceiver is rectified by D5 with current limiting provided by C7 R3 and R7 The resulting DC voltage turns on Q1 Q2 turns on latching Q1 this will remain latched until the DC bias provided by R16 and R20 is removed by the action of SW1 The intention of this circuit is to stop the relay contact chattering and possibly burning out Q1 turns on Q4 switching Q3 off changing the antenna input over to the transceiver The PTT input from Skt3 forward biases D10 switching on Q3 in the same way protection from the turn off back EMF of the relay is provided by D6 Manual antenna change over is provided by SW1 forward biasing D9 acting on the same switching transistors TX indication is provided by the RED led DI From the antenna switch signal is passed through the limiting circuit of D7 and D8 these diodes are incorporated to protect the receiver circuit in the event of static discharge or RF from an incorrectly connected transceiver in the later case R9 a 200mA SMT fuse is designed to blow this may or may not cause further damage dependent on the level of RF applied Version R1 1 From the limiter signals are passed through one of five band pass filters switched by the microcontroller depending on the tuned frequency Good filtering is important as the QSD circuit is sensitive to odd harmonics of the received frequency these need filteri
20. socket shield Connect black Ve meter lead to ground The resistance reading should be gt 100k Ohms if not look for a short circuit or other fault between the USB socket and regulators U2 and U3 Voltage checks Set the multimeter to a range suitable to read 5V DC and connect the black Ve lead to ground it may be best to temporarily solder a ground wire to one of the antenna connector ground pads to allow easy attachment of the meter clip lead Ensure the work area is clear of any stray components or metallic objects and that the PCB is resting on an insulating surface then connect the PCB to a PC using an appropriate USB lead it is normal for the PC to detect a USB source and report it as faulty Measure the two supply voltages first measure the voltage on TP4V6 this should be 4 6 0 1V RK Hunter Construction manual 10 M oltage test points be C36 R36 _ Measure the voltage on TP3V3 this should be 3 3 0 1V Remove the USB lead a dot on L PCB aligns M Nerizwith dot on Writing is upside down c29 C28 TRSY TP4V6 4 R27 If either of the voltages incorrect diagnose the cause before continuing as the expensive 51570 will be destroyed with an incorrect supply voltage Fit the 51570 device in position U4 this device is packed in a separate bag along with the other surface mo
21. t circuit on the Hunter PCB Version R1 1 Voltage tables SDR mode Pin Q1 Q2 Q3 Q4 Pin Q5 B 0 4 12 3 73 4 57 D 4 4 4 12 0 4 41 3 73 0 0 4 12 4 57 4 57 S 0 38 U1 U2 U3 U4 U5 U6 U7 1 4 31 4 79 0 3 29 2 25 4 53 0 2 2 86 4 79 4 58 3 29 2 27 2 21 2 21 3 0 0 3 3 0 2 27 2 27 2 27 4 0 4 58 Tab 4 58 3 3 0 4 42 2 29 5 4 52 0 4 1 63 2 27 2 21 2 29 6 4 52 Tab 0 0 2 27 2 21 2 27 7 4 55 3 3 2 32 0 2 33 8 0 3 3 4 51 2 21 0 9 0 77 0 2 27 10 0 77 4 42 2 27 11 3 3 2 27 2 27 12 3 3 2 22 2 27 13 0 4 53 2 23 14 4 53 4 53 2 21 15 0 0 16 0 4 56 17 0 18 0 19 0 20 4 55 21 0 22 0 23 0 24 0 25 4 39 26 0 27 0 28 0 TRX mode Pin Qi Q2 Q3 Q4 Pin Q5 B 0 0 4 56 3 8 D 4 4 0 0 0 4 56 0 0 0 4 58 4 58 S 0 38 U1 U2 U3 U4 U5 U6 U7 1 4 31 4 79 0 3 29 2 25 4 56 0 2 2 86 4 79 4 58 3 29 2 27 4 56 0 3 0 0 3 3 0 2 27 2 28 2 28 4 0 4 58 Tab 4 58 3 3 0 0 0 5 4 52 0 4 1 63 2 27 4 56 0 6 4 52 Tab 0 0 2 27 0 2 28 7 4 55 3 3 2 32 0 2 28 8 0 3 3 4 51 0 0 9 0 77 4 56 2 28 10 0 77 0 2 28 11 3 3 2 27 2 28 12 3 3 0 2 28 13 0 4 56 0 14 4 53 4 56 0 15 0 0 16 0 4 58 17 0 18 0 19 0 20 4 55 21 0 22 0 23 0 24 0 25 4 39 26 0 27 0 28 0 Circuit Diagram Poue
22. tches the antenna to the transceiver this can be confirmed by the RED TRX LED lighting and power being observed on the SWR power meter Note the SDR TRX switch will have to be pressed in and then out again to switch the antenna back to SDR Version R1 1 In Use Hunter only has two physical controls SDR TRX Pressing this button will switch the antenna to the attached transceiver this should be used before transmitting Hunter has RF sensing which will switch the antenna to the transceiver automatically but this shouldn t be relied on as for a short period the transceiver will not be loaded To avoid this happening repeatedly the switching circuit latches in the transmit mode this can be released by depressing and then releasing the SDR TRX switch Attenuator A 20dB attenuator is activated when the switch switch is pressed in this can help stop overloading when using large antennae or from very strong signals the switch should be left out if not required RK Hunter Construction manual 4 Fault finding Most faults are due to poor soldered connections or components misplaced it is very rare to be supplied with a faulty component Before making any measurements look carefully for any poor soldered joints short circuits or incorrectly fitted components Should fault finding be necessary a table of voltages 1s given below voltages were measured with the LPF switched to 4 8MHz tuned frequency 7 1
23. ungblood K5SDR in the Flexradio and later by Tony Parks KB9YIG in the softrock series of receivers In addition the Hunter also has circuitry to enable its use as a panoramic adapter the receiver can be placed inline between antenna and transceiver and incorporates a changeover relay allowing antenna switching between the SDR receiver and the connected transceiver Hunter translates a section of the HF band to a frequency suitable for processing by an external sound card and PC for a sound card sampling at 192kHz the displayed bandwidth approaches 190kHz similarly bandwidths of 90kHz for 96kHz sample frequency and 45kHz for a 48kHz sample frequency can be expected SDR receiver performance is heavily reliant on the sample rate and dynamic range of the sound card used many PCs laptops included now incorporate a 24bit 96kHz sound card this specification is recommended as a minimum If the PC doesn t have a suitable sound card second user parts are inexpensive when sourced from eBay Frequency control and power for Hunter is provided by a single USB connection with the PC current consumption is about 150mA so ifa separate USB hub is used it will need to be of the powered type RF sensing is provided to automate the change over this can be overridden with a push switch If transmit power is sensed the relay will remain switched to the transceiver until the manual switch is depressed then released this is to stop repeated relay operatio
24. unt parts First apply solder to one pad only whilst remelting the Version R1 1 solder place 51570 squarely and centrally between all pads note that the solder pads are underneath the device with only a small witness up the side use this witness as an indicator to centralise the chip Pin one is indicated by a dot on PCB and device see photo for details When you are sure the device is correctly orientated solder remaining 7 pads ensure the witnesses are also soldered refer to photo _ Fit U1 to it s socket Pin one end of the chip is marked by a notch on the PCB and by a dot on the chip The pins may need bending inwards slightly to align with the socket this is easily achieved by carefully pressing all pins on one side of the chip at a time against a flat surface Assembling to case The case front and rear will need drilling to accept the connectors and buttons etc Print the drilling template using Adobe reader note that Page scaling should be set to None When printed measure the scales to ensure they have printed accurately The drilling templates can be fitted to the inside of the end panels using double sided sticky tape or a non permanent adhesive First drill the round holes to the indicated size its best to work up in drill size starting with perhaps a 2mm drill The drill can be centred by first applying a little pressure before allowing the drill bit
25. ure of 360 C is recommended although to remove the enamel from the enamelled copper wire a higher temperature will be required There isn t space here to give full tuition on surface mount soldering techniques you are referred to the You tube links on the Radio Kits web site for video demonstrations of various techniques Component identification Resistors These have a white ceramic substrate with a black covering marked with the value U7 e Ceramic capacitors pe eR Generally brown in colour and a without any markings if they t Version R1 1 become mixed it won t be possible to identify them without a capacitance meter Diodes and transistors Diodes and transistors use the same three leg meme ductors package aR n ductors 4 525 C BR38C49 Inductors Inductors have plastic bodies the colour is dependent on manufacturer Component placement First to be fitted are the surface mounted integrated circuits these are easiest to fit without other components getting in the way IC s are static sensitive so take sensible precautions IE don t work on a nylon carpet and use an earthed soldering iron First tin one corner pad with a little solder then sit the IC on this carefully aligning all pins and ensuring the device orientation is correct Whilst still holding the chip with tweezers or by applying light pressure on top of the IC apply the soldering iron to th
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