Transcription

Firefly SDR THThrough hole version of the Firefly SDRHendricks QRP KitsSoftware Defined Receiver for 30m and 20mWith 3w CW Transmitterby Dan Tayloe, N7VEFirefly SDR TH v112-26-06Page 1 of 66

Table of ContentsSpecifications. 4SDR Receiver. 4Transmitter. 6Note to the Reader . 7Building the Kit. 7Things you will need. 7Parts List . 10Tools and Construction Hints . 13Bare PC Board Pictures . 14Power Connections and 5 and 6v Regulators . 155 and 6v Regulator Tests. 17Sidetone monitor Amplifier . 18CW Side Tone Monitor Amplifier Test . 19Keyer Circuit. 20Keyer and CW Side Tone Monitor Amplifier Test . 21Receiver Side Local Oscillator . 22Receiver Side Local Oscillator Test . 2390 Degree Phasing Section and LO Buffer. 2490 Degree Phasing Section and LO Buffer Tests . 25Detector Circuit. 26Detector Circuit Tests . 27Receiver Audio Preamp . 27Receiver Audio Preamp and Detector Tests . 28Receiver Front End and T/R Switch . 29Receiver Front End and T/R Tests. 31Transmitter VXO . 32Transmitter VXO Tests. 33Transmitter Buffer Circuit . 34Transmitter Buffer and T/R Switch Tests. 35Transmitter PA Circuit. 37Transmitter PA Tests . 38Board Connections. 40System Connection Block Diagram. 46Mounting into a case. 49A Note on PC Sound Cards . 50Pre-Loading of SDR software on the PC. 50Notes on loading PowerSDR . 52SDR Receiver Resources . 54Receiver Tune Up . 55Operating the Firefly SDR . 56Firefly SDR Customizations and Optimizations. 57Appendix A. Parts List. 60Appendix B. Keyer Instructions . 62Firefly SDR TH v112-26-06Page 2 of 66

List of FiguresFigure 1. Working over an oversized cookie sheet is highly recommended to catch stray parts . 8Figure 2. A temperature controlled soldering helps a lot. 750 degrees is recommended form non-leadtinned boards. 8Figure 3. A very pointed soldering iron tip is a very big help for small components . 9Figure 4. Headband Magnifiers. “Mag-eyes” from JoAnn Fabrics . 9Figure 5. Package as it arrives from Hendricks QRP Kits. 10Figure 6. Internal contents of the box – Three parts packs plus the PC board . 11Figure 7. List of pre-mounted parts . 11Figure 8. Inventory of band specific parts included in the kit . 12Figure 9. Parts common to all bands. 12Figure 10. Top side view of the Firefly SDR TH board . 14Figure 11. 5v, 6v Regulator and 12v input areas highlighted. 15Figure 12. Lead forming of the LM78M05 5v regulator before installation . 15Figure 13. 5v regulator, protection diode, and 9v temporary connection. Note D7 diode polarization!16Figure 14. 6v regulator installed. Note IC3 flat side orientation and C13 stripe orientation. 16Figure 15. 5v and 6v regulator output test points . 17Figure 16. Parts location of the CW side tone monitor amplifier. 18Figure 17. Side tone monitor amp. Note IC2 polarity and black stripes on C1 and C73. . 18Figure 18. Note that all resistors are installed vertically as shown above, fat end on the marked circlearea. 19Figure 19. Location of keyer circuitry . 20Figure 20. Keyer Section. IC8 Notch is at the top end. 47K keyer test resistor shown with audio testjack. 20Figure 21. Location of the receiver crystal oscillator circuitry. 22Figure 22. Receiver LO parts mounted. 22Figure 23. Location of the receiver crystal oscillator circuitry. 24Figure 24. Receiver LO section. Note the notch location on IC6. Note L2 is mounted on end like theresistors. . 24Figure 25. Location of the detector circuit. 26Figure 26. View of installed detector. Make sure C19, C20 and C86 are installed as shown. 26Figure 27. Top placement of receiver audio preamp stage. 27Figure 28. Close up of the parts in the audio preamp stage. 27Figure 29. Top placement of receiver front end and T/R switch . 29Figure 30. Close up of receiver front end and T/R switch. 29Figure 31. Close up of input receiver filter inductor L9. 30m values shown. For other bands see text. 30Figure 32. Location of the transmitter VXO. 32Figure 33. Close up of installed transmitter VXO parts . 32Figure 34. Location of the TX Buffer circuit. 34Figure 35. TX buffer parts installed. IC7 notch location, close up of D3 orientation shown. 34Figure 36. Test points for the T/R switch in the receiver front end. 35Figure 37. Location of keyer paddle inputs to test the T/R switch . 36Figure 38. View of the PA circuit. 37Figure 39. View of the PA circuit. Note band orientation of D1. 37Figure 40. Antenna coax connection to transceiver. Upper connection is ground, lower is antenna. . 39Firefly SDR TH v112-26-06Page 3 of 66

Figure 41. Connections for J1, I/Q (R/L) audio output to the PC sound card input . 40Figure 42. Connections of the I/Q audio output to its audio jack . 40Figure 43. Connections for X1 and R98, CW side tone monitor speaker and 100K CW speed pot. . 41Figure 44. Connections to CW mon speaker jack, CW speed pot. Remove temporary resistor acrossR98. 41Figure 45. Connections for keyer paddle inputs (X2) and for keyer programming push button switch(S2). 42Figure 46. Visualization of paddle jack and keyer programming switch connections . 42Figure 47. Connections for TX spot switch (S1) and TX VXO 10K tuning pot (R99). 43Figure 48. Visualization of TX tuning pot and VXO spot switch connections. Switch shown “Spot On”. 43Figure 49. Ext Audio connector. Connection to PC audio output. . 44Figure 50. Visualization of the optional connection to the PC audio output. Mono input only. . 44Figure 51. Optional mute output signal (0v mute, 5v normal). 45Figure 52. Connections for 12v to the board . 45Figure 53. Antenna Connections. 45Figure 54. External connections from a case view . 46Figure 55. Diagram of the major external interfaces of the Firefly SDR, less front panel controls. 47Figure 56. System view of combined RX/TX sidetone configuration. 48Figure 57. Mount all four corners of the main board using the mounting hardware as shown. . 49Figure 58. Homebrew case fashioned out of double sided PC board, 5” x 3.5” x 1.375”. 49Figure 59. Select the setup tab to get to this window. Select SoftRock, and set the center frequency. 52Figure 60. Sheet used to calibrate the signal strength readings in Power SDR . 52Figure 61. DSP/Image Reject tab used to null opposite sideband signal. 53Figure 62. Generic settings – NB on, 500 Hz filter, CWU, proper band selected (30m here) . 53Figure 63. Adjustment points for tuning up the receiver. . 55Figure 64. Pi Attenuator values – 3 db to 30 db . 58Figure 65. Tx VXO tuning linearity improved by using an external 4.7K resistor . 59Figure 66. Common, non-band specific parts. 60Figure 67. Band specific inductors . 61Figure 68. Band specific parts . 61Figure 69. A Function Table of the Keypress Combinations . 62Figure 70. Mem dit menu (PAR mem to advance to the next menu item). 63Figure 71. Mem dah menu (PAR mem to exit) . 64Figure 72. Mem switch menu (PAR mem to advance to the next menu item). 65Figure 73. Mem both menu (PAR mem to exit). 65SpecificationsAs measured from current prototypes, some variance in performance is expected from unit to unit.SDR ReceiverTuning range: 30m:10.120 MHz /- 24 KHz ; 20m: 14.065 /- 24 KHz using free software packagessuch as PowerSDR and RockyFirefly SDR TH v112-26-06Page 4 of 66

Curent Drain: Approximately 28 ma @ 12v.Supply voltage range: 9 to 13.8vReceiver bandwidth: Wideband SDR receiver 3 db down at /- 24 KHz. Audio selectivity via PCsoftware.MDS receiver sensitivity: Dependent on the PC sound card used. 30m measured: -127/-128 dbm in500 Hz using a Presonus Firebox and PowerSDR software.Third order distortion dynamic range (IP3DR): 93 dbBlocking Dynamic Range (BDR): 100 dbFirefly SDR TH v112-26-06Page 5 of 66

TransmitterPower Output- 3 to 3.5w at 12vNote: TX designed for CW type transmit duty cycle, finals rated to 2.4w power dissipation.Prolonged key down operation is not advised.TX tuning range- 30m: 10.108 to 10.119 KHz, 11 KHz range with 10.120 MHz crystals;- 20m: 14.049 to 14.065 KHz, 16 KHz range with 14.065 MHz crystals;Note: Exact low end TX tuning range will vary from crystal pair to crystal pairTX harmonic output- All output harmonics less than -50 dBcFirefly SDR TH v112-26-06Page 6 of 66

Note to the ReaderIn the interest of “time to market”, I am shamelessly lifting the following few sections kit buildingsections from the NC2030 manual. Please ignore the references to the NC2030 – Dan, N7VEBuilding the KitThings you will needJacks, pots, switches, and push buttons, and a case specifically:- Five 1/8” stereo jacks (I/Q audio output, Monitor speaker output, Paddle inputs, Audio input from PC,mute signal output)- One small push button switch, normally open (programming button for the keyer)- One sub-miniature SPST switch (used for spotting the TX VXO on frequency)- One 100K linear panel mounted pot (keyer speed pot)- One 10K linear panel mounted pot (used to tune the TX VXO frequency)- One antenna jack- One rear 12v power connector- One case. Dimensions should be at least 5” in depth, 3.5” wide and 1 3/8” tall. The case should bemetal to provide shielding on the TX VXO from the radiated antenna signal.- One 1/4w resistor for testing, 10K to 100K (47K recommended)- 9v battery clip (for temporary power connection for testing)- Fresh 9v battery (for a low current power source for testing)- Clear nail polish (“Sally Hansen Diamond Strength” highly recommended for hardness. Source: Ulta)- Tweezers- Solder sucker (highly recommended) or solder wick- Temperature control soldering iron with a fine tip- 8 pin socket for the keyer chip (optional)- Magnifying headpiece and/or magnifying glass. 3.5 power reading glasses may work also. Try themon and check for focus at a 6 to 8” operating distance.- Cookie sheet (highly recommended for building on top of in order to catch stray parts)An important note:SDR radios have traditionally had a number of complaints concerningperformance problems related to intermittent connections in the low level audio jacks. The use of goodconnectors and gold plated audio cables plugs have proved to be helpful in obtaining consistent day today receiver performance. Cheap audio jacks and cheap audio cables provide for a good low coststarting point, but can be problematic in the long run.Good shielded audio cables between the receiver low level I/Q audio output and the input to thecomputer sound card is very helpful in keeping out spurious signals. Given a choice, make this cable asshort as possible.Firefly SDR TH v112-26-06Page 7 of 66

Figure 1. Working over an oversized cookie sheet is highly recommended to catch stray partsFigure 2. A temperature controlled soldering helps a lot. 750 degrees is recommended form non-lead tinned boardsFirefly SDR TH v112-26-06Page 8 of 66

Figure 3. A very pointed soldering iron tip is a very big help for small componentsFigure 4. Headband Magnifiers. “Mag-eyes” from JoAnn FabricsFirefly SDR TH v112-26-06Page 9 of 66

As far as magnification, I think that common reading glasses may be just as good. Try 3.5 or 3.25magnification glasses. Try them on and check the focus distance. Ideal is a focus distance of about 8inches.I use the above Mag-eyes with my normal 1.5x reading glasses. I can gang both the reading glasses andthe Mag-eyes together to get a really good, close up look at the parts. However, it does drive my eyes abits nuts switching from no glasses to glasses, to Mag-eyes, to glasses plus Mag-eyes.Parts ListFigure 5. Package as it arrives from Hendricks QRP KitsFirefly SDR TH v112-26-06Page 10 of 66

Figure 6. Internal contents of the box – Three parts packs plus the PC boardThe bare board comes with five pre-mounted surface mounted parts listed below:Figure 7. List of pre-mounted partsFirefly SDR TH v112-26-06Page 11 of 66

The parts are broken into band specific and common parts. Here are lists of both:30mList215113221320mList111411221213100 pf150 pf180 pf2.2 pf22 pf4.7 pf47 pf470 pf10 uH choke10.120 MHz xtal2.2 pf100 pf120 pf150 pf27 pf33 pf330 pf4.7 pf47 pf68 pf4.7 uH choke14.065 MHz xtalFigure 8. Inventory of band specific parts included in the kitQty11283213112Value0.01 uf0.1 uf100 uf150 pf22 pf22 uf47 pf5 pf50 pf11111N5262B51v 253300100K1k3.3K33K47K75K8.2K15K trim potFigure 9. Parts common to all bandsFirefly SDR TH v112-26-06Page 12 of 66

Tools and Construction HintsIn building this transceiver myself and creating the manual, I have had some problems. These fall intoseveral different categories:1)2)3)4)5)6)IC pins not truly solderedICs mounted backwardsResistors and capacitors not soldered to the right set of padsNot all parts were installedBad resistor (part was open)Leads not totally stripped on the toroid coresPlease learn from my mistakes. Each time an IC is mounted, check the mounting polarity twice beforesoldering it in. I suggest checking the IC polarity, soldering down one corner pin, and then checking itone more time before finishing the job. I think the old saying is “measure twice, cut once”.I have once been bit by not mounting all the parts. Double check the pictures against your kit to makesure things end up in the right place.You may find that the components in the pictures may be slightly different from what is in your kit.This may be partially due to the fact that the pictures are of the 20m version.This manual has been set up to build a section, and then test it. The tests are normally quite simple. Thisshould find most problems as we go from stage to stage rather than getting to the end and not knowingwhere to start.I found building the transceiver over a large cookie sheet eliminated the problem of dropping parts andloosing them. However, when doing the applied voltage tests, you should place a few sheets of cleanpaper under the boards to keep them from shorting out against the cookie sheet.I find that this radio can be built in about six hours. One good Saturday should do it.Firefly SDR TH v112-26-06Page 13 of 66

Bare PC Board PicturesFigure 10. Top side view of the Firefly SDR TH boardFirefly SDR TH v112-26-06Page 14 of 66

Power Connections and 5 and 6v RegulatorsFigure 11. 5v, 6v Regulator and 12v input areas highlightedI suggest using a 9v battery clip to temporarily supply power to the board. This is a low current,temporary power connection that protects the board in case of a problem. The 9v battery clip is notsupplied.Figure 12. Lead forming of the LM78M05 5v regulator before installationFirefly SDR TH v112-26-06Page 15 of 66

Figure 13. 5v regulator, protection diode, and 9v temporary connection. Note D7 diode polarization!Install IC11 (LM78M05). Make sure hole of the regulator matches up with the mounting hole onthe board!Install 0.1 uf caps (marked “104”).C11 andC12Figure 14. 6v regulator installed. Note IC3 flat side orientation and C13 stripe orientation.Install IC3 (LM78L06), D7 SB320. Double check the polarity against the above picture!Check the diode band polarity, and match the flat side of T3 against the flat side outline on theboard.Install 0.1 uf caps (marked “104”).C83,C84x andC45Install C13, 100uF polarized capacitor. This is a polarized capacitor, so make sure it is installed withthe correct polarization. The black stripe on the top of the cap is the negative side of the capacitor. Thenon-striped side matches with the “ ” symbol marked on the board. Double check against theorientation on the board.Firefly SDR TH v112-26-06Page 16 of 66

5 and 6v Regulator TestsFigure 15. 5v and 6v regulator output test pointsThe drain on the 9v battery should be about 10 ma. The current drain can be tested by connecting the9v battery by one terminal only, then connecting a voltmeter between the remaining battery terminal andremaining 9v battery clip terminal.The input voltage to the board is diode protected. Thus you will not damage the board by hooking thebattery up backwards.The tab of the 5v regulator makes a good ground connection point. All four corner mounting hole aregrounded on this board and also make good ground test points. All voltage measurements should useone of these grounding points.Measure and verify the 5v and 6v outputs as shown above. However, if the current drain is right, it ishighly likely that all is well.It should be noted that the idle current of the regulators vary quite a bit from device to device and thatthe total current drain at this point could be different by several ma.At this time, remove the 9v battery connection.Firefly SDR TH v112-26-06Page 17 of 66

Sidetone monitor AmplifierFigure 16. Parts location of the CW side tone monitor amplifierFigure 17. Side tone monitor amp. Note IC2 polarity and black stripes on C1 and C73.Firefly SDR TH v112-26-06Page 18 of 66

Figure 18. Note that all resistors are installed vertically as shown above, fat end on the marked circle area.Install the following parts in the following order:-Install IC2 (LM386-4). Double check the orientation of the IC before soldering it in.Solder one pin, double check the orientation with the picture above, and then solder the rest ofthe pins.-Install C1 & C73 100 uf large blue electrolytic cap. Double check the polarity of the blackstripe against the photos above.-Install R8 (5K trim resistor). Don’t forget to solder down the trim resistor! It snaps in placewell and is easy to forget!-Install R5 and R6 (18 ohm – brown-grey-black-gold), R11 (8.2K – grey-red-red-gold)R32 (1K marked brown-black-red-gold) and R10 (47K- yellow-violet-orange-gold)-Install-Install Q9 (BS170), R9 (3.3K- orange-orange-red-gold). These two parts are not shown asinstalled in the pictures above, but were added to this section after the pictures were taken.C5 &C22 (0.1 uf – marked 104)CW Side Tone Monitor Amplifier TestThis will be tested more completely after the next section. The easiest test is to check the board currentdraw when connected to the 9v battery. At this point the current drain is in the 15 ma range.Firefly SDR TH v112-26-06Page 19 of 66

Keyer CircuitFigure 19. Location of keyer circuitryFigure 20. Keyer Section. IC8 Notch is at the top end. 47K keyer test resistor shown with audio test jack.Firefly SDR TH v112-26-06Page 20 of 66

Install IC8 (12F629). Note the IC8 notch orientation in the above picture before soldering! Solderone pin, double check the orientation with the picture above, and then solder the rest of the pins.Install 0.01 uf capacitors (marked “103”):Install 0.1 uf capacitors (marked “104”):Install 3.3K resistors:R59,R60, andC59,C91,C60, C62, andC64,C65, andC63.C77R71 (marked orange-orange-red-gold)Install 1K resistors: R56, R58 (marked brown-black-red-gold). R56 is hard to find. It is rightbelow the two large blue 100 uf caps in the side tone amplifier.Install 8.2K resistors:R55 (marked grey-red-red-gold)For temporary testing purposes connect a resistor somewhere in the 10K to 100 K range as shown aboveacross the connections for the CW speed pot R98. I used a 47K resistor (not included) because that iswhat I had closest to hand. This will allow the keyer chip to send “FB” out of the side tone speakermonitor output when the board is powered up. Alternatively you could hook up the cw speed pottemporarily.Keyer and CW Side Tone Monitor Amplifier TestConnect the 9v battery. If no monitor side tone external speaker is connected, the board current drawwhen connected to the 9v battery will start at 16 ma, then quickly drop back to 15 ma. The 1 madifference is the keyer chip turning on and sending “FB”. The keyer chip will then turn off when done,reducing the current back down to 15 ma.The sidetone volume trimmer R8 is turned all the way down from the factory. You will need to turn itup (half way?) to get any side tone volume.A further and more complete test is to connect an external speaker (or set of headphones) to the CW sidetone monitor output, X1. The picture above shows a headphone output connected temporarily acrossX1. R8 is the volume control for this CW side tone output, and the output is quite loud. Set R8 to acomfortable listening level.With a speaker attached, the current drain increased to 20 ma (I have seen 54 ma!) when the board isfirst powered up and the “FB” is sent. The current then dropped back to 15 ma. The high current valuewill depend on your exact R8 volume setting and the impedance of the external speaker.Note: The CW Keyer may not reset pr

Firefly SDR TH Through hole version of the Firefly SDR Hendricks QRP Kits Software Defined Receiver for 30m and 20m With 3w CW Transmitter . Select SoftRock, and set the center frequency. 52 Figure 60. Sheet used to calibrate the signal strength readings in Power SDR. 52 Figure 61