HF Signals The home of BITX transceivers Ashhar Farhan, VU2. ESEThe original BITX was published on the Internet in the year 2. In the last 1. 3 years, it has grown to become one of the most popular rigs among radio amateurs around the world. Y9y_cJ28HtY/hqdefault.jpg' alt='Bitx20 Version 3 Manual' title='Bitx20 Version 3 Manual' />Radio electronics blog. Homebrew ham radio. SolderSmoke podcast. QRP. Downloads. MKARS80 construction manual version 1. Latest version for currently supplied kits. MKARS80 construction manual version 1. Spanish. DISCONTINUED TJ2A 2 Band SSB CW Handheld Transceiver. Can be set to operate on 2 bands from 160m 10m. Output power 3. 5 4 Watts. The BITX4. 0 board is this very classic now available as a fully tested board that is easy to hookup, modify and operate. You can read the original article that described the BITX at http phonestack. Download the circuit diagrams Whats special about this version of the BITX Uses a 1. MHz IF and a Si. MHz as a rock solid local oscillator. The entire transceiver fits into a single large and easily accessible PCBThough it works on 4. It has a separate power line for the PA. Bitx20 Version 3 Manual' title='Bitx20 Version 3 Manual' />12032013. Firmware version v1. Was added to the setup menu, the calibration function of crystal reference 125Mhz for fine adjustment of the output frequency. By increasing the PA power voltage, the transmit power can be increased. The components supplied with the board will get you up on air without any special skill. Read the Wire Up to understand how it is hooked up. Development Notes. Almost all modes of radio communications share a natural principle that the receivers and transmitters use the same line up of circuit blocks except that the signal direction is reversed. PAC12 Assembly Manual 2. PAC12 Assembly Manual v3. Meter Coil Assembly V2. PAC 12 Multiband Assembly V2. Dual Band 20 and 40m Trap Dipole Antenna 9. For the version that ships from Europe use this URL http For the version that ships. QRP Kits and Components worldwide suppliers of ham radio kits. HTB1aXOeHXXXXXaSXVXXq6xXFXXX8/112211865/HTB1aXOeHXXXXXaSXVXXq6xXFXXX8.jpg' alt='Bitx20 Version 3 Manual' title='Bitx20 Version 3 Manual' />The CW direct conversion transceiver is the simplest illustration of this principle. A more complex example is the bidirectional SSB transceiver. Bi directional SSB transceivers have been quite common in amateur literature. A transceiver was described in the ARRL SSB Handbook using bipolar transistors. W7. UDMs design of bidirectional amplifier as the basis of bidirectional transceiver is referred to by Hayward and De. Maw in their book Solid State Design. RISQGp-3MBI/hqdefault.jpg' alt='Bitx20 Version 3 Manual' title='Bitx20 Version 3 Manual' />The bidirectional circuitry is often complex and not approachable by the experimenter with modest capability. The Raduino. The Raduino is a very powerful, hackable, easy to program board that comes loaded with the BITX4. The lower side OSCILLATORS connector has 1. A 5 pin header that sits on it takes 1. DDS output to be connected to the main boards DDS connector. An 8 pin CONTROLS connector on the top connects to the tuning pot and future switches and controls. The tuning system is very precise and easy. The tuning pot covers 5. KHz of the band and the edge of the tuning pots range allow you to scan up and down the rest of the band in 1. KHz steps. The broad band bi directional amplifier. My interest in bidirectional transceivers arose after looking at an RC coupled bidirectional amplifier in the book Experimental Methods in RF Design p. An easily analyzed circuit that was simple and robust was required. It began its life as an ordinary broad band amplifier There are some interesting things about this circuit The power gain, and the input and output impedances are all related to the resistor values and do not depend upon individual transistor characteristics. We only assume that the transistor gain is sufficiently high throughout the frequencies of our interest. The precise value of the transistor characteristics will only limit the upper frequency of usable bandwidth of such an amplifier. This is a useful property and it means that we can substitute one transistor for another. You can use 2. N3. BC5. 47, 2. N2. 22. Just about any transistor will do The power gain is not a function of a particular transistor type. We use much lower gain than possible if the transistor was running flat out. But the gain is controlled at all frequencies for this amplifier. This means that this amplifier will be unconditionally stable it wont exhibit unusual gain at difference frequencies. In order to make bidirectional amplifiers, we strap two such amplifiers together, back to back. By applying power to either of amplifiers, we can control the direction of amplification. This is the topology used in the signal chain of this transceiver. The diodes in the collectors prevent the switched off transistors collector resistor 2. A close look will reveal that the AC feedback resistance consists of two 2. K resistors in parallel, bringing the effective feedback resistance to 1. K. All stages of amplification in this transceiver work this principle. Diode mixers. The diode mixers are inherently broadband and bidirectional in nature. This is good and bad. It is good because the design is non critical and putting 8 turns or 2. The badness is a little tougher to explain. Imagine that the output of a hypothetical mixer is being fed to the next stage that is not properly tuned to the output frequency. In such a case, the output of the mixer cannot be transferred to the next stage and it reflects back into the mixer. Ordinarily, if the mixer was a FET or a bipolar device, this reflected power just heats up the output coils. In case of diode ring mixers, you should remember that these devices are capable of taking input and outputs from any port and these inputs and outputs can be from a large piece of HF spectrum, hence the mixer output at non IF frequencies reflects back in the mixer and mixes up once more creating a terrible mess in terms of generating whistles, weird signals and distorting the original signal by stamping all over it. A simple LC band pass filter that immediately follows the diode ring mixer will do a good job only at the frequencies it is tuned to. At other frequencies, it will offer reactive impedance that can cause the above mentioned problems. It is a requirement that the diode mixers input and output ports see the required 5. In other words, they require proper broadband termination. Using broad band amplifiers is a good and modest way of ensuring that. A diplexer and a hybrid coupling network is a better way, but it would be too complex for this design. Circuit Description. Although simple, every effort was made to coax as much performance as was possible given the limitations of keeping the circuit simple and affordable. The Receiver. The RF front end uses a high performance 3 section band pass filter for strong image and IF rejection. The three poles of filtering provide for a no tune bandpass filter that needs no adjustment. The 7 MHz bandpass filter. Each vertical division is 5 MHz. The RF Amps. An RF amplifier follows the RF band pass filter Q1. There is 8m. As through the RF amplifier and the post mix amplifiers to keep the signal handling capacity of the circuit above average. The Post mix amplifier Q2 does the job of keeping the crystal filter as well as the diode mixer properly terminated. The crispness of the receiver is more due to this stage than anything else. An improper post mix amplifier easily degrades the crystal filters shape and introduces spurious signals and whistles from the diode mixer. The Optional VCOThe BITX4. Raduino to make drift free, precise tuning easy. For the purists, a voltage controlled oscillator that covers 4. Mhz to 5 Mhz to cover the 7. Mhz to 7. 2 MHz is an alternative. Just plug out the Raduino and solder the supplied yellow VFO coil. A varactor was chosen over a variable capacitor as it is easier to tune. Mounting a VFO capacitor properly is difficult. Good quality tuning capacitors are nolonger available. Those who like slower tuning rates with the VCO could use a multiturn 1. K linear pot instead of a regular potentiometer. The VCO is fed via a broad band amplifier into the doubly balanced mixer. The trimmer provides exact band covereage. This oscillator has low noise though it does drift a little like all analog oscillators. It settles down to a very imperceptible drift within 1. Tip Turn the BITX4. The receiver withe the VCO takes just 9. A current. The Crystal filter. Solder. Smoke. Solder. Smoke Global Adventures in Wireless Electronics. This is now the archive site for the Solder. Smoke Podcasts.   It will be updated periodically, but new podcast episodes will be announced via the blog  http soldersmoke. Solder. Smoke Podcast 1. Weve got a problem   Pete Juliano and the QRP Hall of Fame     PLEASE HELP BENCH REPORTSPete Releases Smoke wiring harnessPetes Dif. X on 6. 0Architecture and Dual Conversion u. BITX   uses ALL THREE clocks on the Si. The Big Kahuna ON HACKADAY with Philco SB1. SEE  QRP BITX6. Cap Stack Hack mod with leadsLet the smoke out of an Si. Several actually. Same day delivery zone for Amazon but no drones or parachutes yet. Installed scanning switch. Observations on 6. All the weird bands have a 6 in them 1. The good  1. 00 watt limit, wire antennas The bad  Kind of cliquish like 7. CQ band.   Channels. Not much activity. Met Josh KE8. CPD on 4. BITX 4. 0 TRIBAL KNOWLEDGE Socketry  How to keep BNC jacks from spinning loose Do you heat shrink Feel Tech Sig Gen might not have blocking cap at the output. Speaking of which, when I spoke of the Ne. I mostly meant blocking caps, not bypass caps. How come they dont have a cable TV channel devoted to radios  They have HGTV Why not HBTV REPORT FROM WINTERFESTBad weather. Tailgaters wimped out Combined forces with Armand WA1. UQO. Met up with Charles AI4. OT. Acquisitions  14 phono jacks, carbon mic, vero board, disc caps, weather radio, LARGE collection of Electric Radios from Armand. Wow. Electric Radio notes   1st Fifty Years of Sideband 1. Jim Musgrove K5. BZHWhy LSB on 7. AMers couldnt follow to top of band. W2, W6, W8s liked phasing, W3, W4, W0 more into filter rigs. Early SSB guys turning on carrier and talking AM hams into SSB RX. Kelvinator Refrigerator rigs. A reading on the homebrewing of SSB rigs. Tony Fishpool on QSO Today  Pete mentioned prominently. Good Hacks from ND6. T on BITXHacks,   Stockton Bridge. MAILBAG Solder. Smoke 1. Patch Adams Main Theme Piano here. March 4, 2. 01. 7BIG NEWS   u. BITX from Farhan. BENCH REPORTSPete Recycling Old Boards. Working on Arduinos and advanced displays Bill SDR Adventures and Misadventures. RTL SDR is fun.   Built HB front end. HDSDR under Windows is fun and easy. Thought about Raspi. Linux, software YUCK. Followed advice of Ken G4. IIB and got a 5. 0 buck tablet with Google Play. Who needs tiny OLEDs  Use a 7 inch tablet as your display Building a Ceramic Resonator for the HRO  4. The value of doing something different. Boxed up my NE6. OLED rig. OLED noise and ACTIVE decoupling. NE6. 02 and MOSFET tips LEXICON  OTD   Obsessive Tinkering Disorder  G6. LBQA Thing of Beauty  Source of Tombstoning term  Don ND6. T. Ken G4. IIBs extremely smooth audio. ON THE AIR On AM on 7. Fun.   Old Military Radio Net and The Lonely Guy Net on 7. Saturday morning. Good old 1. 7 meters. Open at mid day. HB2. HB on 4. 0 with W0. PWE. Listening on 6. Hambrew magazines disappeared, but are back now. EMRFD Classic Edition available. New Posts to BITX HACKSMAILBAG Gloves follow up. Not a good idea. VK3. YEs QRP by the Bay event  and a new bookColin M1. BUU achieves Mountaingoat status. Martin A6. 5DC Jo. O MMM in the UAETom NY2. RF Editorial with mention of Jo. O Lots of Al Fresco rigs W8. LM BITX on a board, Brad WA8. WDQ DC RX, KA4. KXX Al Fresco OZ DSBON6. UU DSB from Spain via Belguim. How To Install Reliance Data Card In Vista. Hugh ZL1. UEM SMALL Si. OLEDCookie Tin rigs VK2. EMUs Biscuit Tin DC RX,  WA7. HRGs Popcorn rig. VK4. FFAB FB LTSPICE intro. Ken G4. IIBs BITX adventure with VERY smooth audio. How smooth We cant say. VU2. XEs BITX with a CAD box. G0. ETPs shockingly beautiful SDR receiver. Alan W2. AEW on the mend with broken ankle. His videos are a treasure trove of tribal knowledge. Solder. Smoke 1. 93   2. Jan 2. 01. 7Report from Pete on BITX 4. Session with California radio club. Update on the BITX4. Module Revolution Check out the BITXHACKS page. Send in contributions. BITX2. Raduino Interview with Farhan with W5. Windows 7 Ultimate E Oem Rar Extractor'>Windows 7 Ultimate E Oem Rar Extractor. KUB    Eliminating the commercial gear. BITX 4. Australia. FB Bench Reports Pete Color Displays KWM 4 OLED MADNESS Bill  Fixing up the old HT 3. HT3. 7 to HT3. 7 QSO with W1. ZB Dabbling in VHF with Ramsey Aircraft band receiver. NOT FUN. Going all IC with Si. OLED NE6. 02 rig. BANDSWEEP OLED Noise and the Active Decoupling solution. Using LTSPICE as a diagnostic or understanding tool. Of Waterfalls, Homebrew Rigs and Casual Critics on 4. Words of Wisdom from W8. JI. LEXICON  HAYWIRE   TOMBSTONE    BIKESHEDDING from Todd K7. TFCSome great recent interviews by Eric 4. Z1. UG Ian G3. ROO  Origins of ROO   Regen at age 8. Hans Summers G0. UPL     Balloons   NO COMMECIAL GEARDavid White WN5. Y          ELECTROLUMINESCENT  RECEIVER EXPLAINEDRob Sherwood NC0. B  MAILBAG  Chris KD4. PBJs BITX 4. 0 with improved stability. Jerry W0. PWE built a DIGITIA  Very nice. Worked Keith N6. ORS and heard me TRGHSMike AB1. YKs Al Fresco Scratch built BITX. But give that LC VFO another chance MikeSteve N8. NM 3. 0 meter rig with salvaged CB LC VFO. FBKeith N6. ORS Franken SDR rig with parts from the 1. FBSKN Bandscan from Mike WA6. ARA  I worked W1. PID Jim What is Mikele up to Rocking Johannesburg and Kirghizstan via local repeaters Solder. Smoke Podcast 1. December 1. N6. QW COMPLETING AN ORBIT TOMORROW Happy Birthday Pete Shortwave Woes   Deception and Disappointment Voice of Vietnam  But it is from Cyprus Creek S. C. Radio Athmeeya Yatra in Punjabi  but it is in Nauen Germany. Yuck  Sort of like these 9 cents per minute on line relay ham stations. Yuck I say You know you are a hardcore homebrewer when a near empty can of Deoxit makes you nervous, so you order more, just in case. Bench Reports  Pete FPM  FPM    FPM  Tell us about itBITX 4. Module in Juliano Blue Explaining the BITX 4. CULTURE SHOCK  Plug and play vs. Hardcore Homebrew. Bill  An EXTROVERTED BITX 4. Module. QRO with 2. Drain  2. 0 watts out. Heatsink upgrade,  Chris KB4. PBJ Thanks. Analog Readout Dymo tape and a Sharpie arrow. REVERSE POLARITY PROTECTION     Where the perfect is the enemy of the good enough. HRO no longer AL FRESCO  Boxed up. Thanks Armand.   Thanks Tim Sutton. Still working on AM receiver. Not inhaling very well. Boatanchor Day  Fixed HT3. Really. Got 1. 60 meter station going. Changed ball bearings on CW key. Next project.   Another BITX 4. Si. 53. 51 and plug in filters. Sideband History  THE SIDEBAND SUZY AWARD. Pete deserves this. I say we revive it. LEX  Al Fresco.       And Tim Walford calls them Blackbox rigs not rice boxes HB2. HB contacts.    Often with guys who built their linear. I say that counts TooMAILBAGxxxxxxxxxxxxxxxxxxxxx. Solder. Smoke Podcast 1. November 6, 2. 01. Solder. Smoke Podcast 1. TRAVELOGUE AND FAMILY DOINGS   Pete sons wedding, Billys Birthday, Gonzalo safely home in the Dominican Republic, MORE BEARS IN THE SHENANDOAH WOODSBIG NEWS  EMRFD LIVES ON   Three cheers for Wes and for Tom Gallagher of the ARRL. BENCH REPORTS PETE   FPM Rig. Some Halli history. A TRUE RIG  Working Japan. WITH 6. WATT LINEAR AMPLIFIER               New FEELTECH  Sig Gen. BILL Farhans BITX Module           Built to Mod, built to get you started in homebrew           Very impressive. BITX in miniature. But completely recognizable. REMARKABLY stable. Farhan personally checking each one.