RF Signal Generator

This signal generator is intended for realignment of radio receivers. The unit is cheap and fairly basic, but perfectly adequate for its intended purpose. However, the output is not a pure sine wave, so the unit may not be suited for more exacting electronic development work.

TR1 is a high gain FET (Field Effect Transistor) and is configured as a Colpitts style oscillator. The oscillation frequency is set by the variable capacitor (C1+C2) and the five pairs of switched inductors. There is significant overlap between the ranges, due to the limited range of readily available inductors. However even by using specially would inductors, four frequency bands would have been needed to cover the range.

More info

A 50 MHz microwattmeter with the AD606

A design for a simple microwattmeter. Input range -75 dBm to + 5 dBm. Frequency range 2 to 50 MHz. Level resolution is 0.1 dBm, frequency resolution is 10 kHz. Log-output about 0.5 – 3.5 Volt. Output for external counter. The meter uses a AD606 as log-converter, a MAX186 as ADC, a PIC16C84 as controller and a HD44780 type LCD. The PIC measures frequency and level of the input signal and calculates level in dBm using frequency-dependant factors.

Schematics, Program flow, program source are available

Homebrew spectrum analyzer by n9zia

Here is a homebrew spectrum analyzer you can build using an old VCR tuner module. Frequency coverage will be from around 80 MHz to 920 MHz and varies slightly with tuner manufacturer. It will also require an old oscilloscope that is capable of X/Y mode with DC input and a receiver which can tune around 47 MHz AM and can also be modified to tap its AM detector.

It’s even possible to downconvert a 2.4 GHz signal down to VHF frequencies using a slightly modified MMDS downconvter. This will allow you to view 2.4 GHz signals with this analyzer.

More info

GBPPR 0 – 1000 MHz Spectrum Analyzer

An experimental spectrum analyzer based around the work done by W7ZOI & K7TAU. Mostly based on junk box or easy to find, low cost components – hence the sloppy design. This is currently an in progress project. It will probably never be finalized and always updated.

More info

HF SDR transceiver – YU1LM

Low power SDR HF I/Q S/H (Sample and Hold) transceiver CW,SSB.- ADTRX1 from 30 kHz-35 MHz with external LO

HF SDR transceiver called ADTRX1 (analog + digital) is compilation of the results and previously published designs. ADTRX1 is working to the 35 MHz and it is a very simple and promising design all with classic size thru holes components. It is very good introduction in to the new SDR technique of the HF transceiver design. Most of demanding specification for HF transceivers are in software now, not in hardware like in classic HF transceiver design. Part 1 is giving description main ADTRX1 board, results and basic connections

Schematics diagram are available: read more

Avala-01 SDR transceiver 1.5Mhz-52Mhz

SDR HF I/Q S/H (Sample and Hold) Transceivers – ADTRX-2 30 kHz -51 MHz and Mono-band One Board QRP 5W SDR HF Transceiver – AVALA-01 from 1.5 MHz- 52 MHz

The ADTRX-2 is a new version of my SDR transceivers ADTRX1 and ADTRX1-1. The design is based on new DR2A+ receiver version which is giving better overall transceiver specification. Transceiver is realized now as one single side PCB design with classic size through hole components..
New mono-band SDR transceiver AVALA-01 is ADTRX-2 transceiver with built in power amplifier and band oscillator all on one board. Transceiver is optimized for work with one sound card and Duncan M0KGK software. With unique PC control setup AVALA-01 is working in all other programs and with all types modulations SSB, CW, DIGITAL….also.

Schematics diagram are available: read more

The HF all-band homebrew transceiver by jg1ead

The home made transceiver covers 3.5 to 3.6 MHz and is CW only. It has the following features:

Characteristics and composition:

• Frequency coverage : 3.5MHz-28MHz 8band
• Mode : SSB/CW
• TX-final : 2SC1947
• Power output : 1W
• RX-RF amp : 2SK125*2(Grounded Gates)
• 1stIF : 48.7265MHz
• TX/RX 1st mixer : MiniCircuit MCL-1
• RX 1st IF amp : MC1350P
• 2ndIF : 11.2735MHz
• TX/RX 2nd mixer : MiniCircuit MCL-1
• RX-2nd IF : MC1350P*2

Schematics diagram are available: homebrew transceiver

T03DSP High Performance Transceiver with DSP IF processing

The goal of this project was to build a high performance HF transceiver with DSP IF processing. I did not try to archive as high parameters as possible, I just tried to get most from the available technology (i.e. mechanical and electrical parts and assembly technology). I tried to keep the design as simple as possible. The design widely uses “software” techniques that allows easy modifications and opens new possibilities.

Features

• Amateur radio bands (160m,80m,40m,30m,20m,17m,15m,12m,10m)
• 0.25 Hz and more (two tuning speed for each mode is available), implemented adaptive tuning step (1x..20x)
• USB, LSB, CW (Normal/Reverse), AFSK, RTTY (decode only by now), (PSK31 with decoder and coder will be implemented in software later)
• Selectivity 100Hz-3000Hz bandwidth in 50Hz steps
• Automatic memory keyer (built in)
• Automatic contest number generation, 5 different number formats available
• Digital RX:S-meter and calibrated input signal power meter
• Digital TX:Output power, SWR and compression (displayed simultaneously)
• 24h real time clock (powered from ionistor during power off periods)
• AFC and tuning indicator in RTTY mode
• Adjustable voice operated squelch for SSB mode
• CAT system compatible with Kenwood command set
• Built in dual tone generator for transmitter testing

T03DSP audio amlifier

Transceiver DSP

Transceiver display

Schematics diagram are available: High Performance Transceiver

PiCaSTAR (Software Transmitter And Receiver) by G3XJP

THE HEART of PIC-A-STAR is the DSP module. This provides both the back-end receiver functionality – as well as SSB/CW generation on transmit. The bottom line is absolutely superb audio quality on both transmit and receive. If you want to test the former, come on the home- brew net frequency (see photo) any day around lunch-time where you will find at least one STAR in operation most days. If you want to test the latter then you will just have to make one.

Software block diagram of PIC-A-STAR DSP functionality

Band pass filter

Timer board circuit

PCB and schematics diagram are available: PIC-A-STAR

A Homebrew High Performance HF Transceiver — the HBR-2000

HBR2-2000 transmitter specifications are: CW/SSB/Digital, 160 to 6 meters, 9 watts output and full QSK on CW. See the QEX article listed at the bottom of this page for information about the QSK system. A 100 watt amplifier is housed in a separate enclosure along with the power supply. The final amplifier incorporates a single MRF151 power MOSFET running on 48 volts. It is followed by separate diplexers and elliptical LP filters for each band. All harmonics and image products are 58 db or more below the carrier level.

Block Diagram of the receiver portion of the HBR-2000.

160 meter filter design with output (mixer side) trap diplexer and insertion loss curves for all bands.

Homebrew VFO

Since low oscillator phase noise is one of the pre-requisites to obtaining a high overall receiver dynamic range, I used a low phase noise analog VFO and mix the output of the VFO to the required injection frequency with separate crystal oscillators which are have a very low phase noise, for each of the 10 lowest amateur radio bands from 160 meters to 6 meters. The VFO tuning range is 1 MHz, (later changes to two 500Khz conseceuive ranges) I can thus tune from the low end of 20 meters up to WWV at 15MHz. As well, a 1 MHz tuning range allows me to cover the lowest 1 MHz of ten meters without having to add another crystal oscillator.

The circuit for the New Front End.

Published articles: QEX Mar-06, Perf. QSK  QST Mar-06, HBR-2000

PCB and schematics diagram are available: HBR-2000 transceiver

An advanced QRP transceiver: QRP2004

The QRP2004 is a major new multi-band HF Transceiver designed by G0BBL, G8BTR and M0PUB. The article was first submitted to the Radio Society of Great Britain (RSGB) in October 2005, passed technical review in May 2006 and was due to be published in “Radcom” magazine starting in October 2006. However, many months later we are still waiting, so we have elected to publish full details on the internet instead.

The QRP2004 uses a microcontroller-based control board which offers a reasonable selection of features without getting carried away with ‘bells and whistles’.

Block schematic

Control board

Band pass filter

Low pass filter

PCB and schematics diagram are available: QRP2004 web site

g3tso 6 band modular transceiver

Direct conversion to 80 and 20 metres is possible using the VFO directly with the 9.MHz IF however, reverse tuning and sideband inversion occur on 80 metres. A switched xtal oscillator and mixer unit was added to provide oscillator injection on the other amateur bands; 160; 40; 15; and 10 metres. No attempt was made to include the WARC bands at this stage. It was deceided to conduct the Band Switching with low capacitance diodes using a switched DC supply, rather than to employ ganged rotary switches.

Band Pass Filter unit

20 Watt HF PA Unit

Schematics diagram are available: 6 band homebrew transceiver

Home brew HF SSB transceiver by VK3EPW

The rig does 80m, 40m, 30m and 20m. SSB and CW.

The rig uses a standard 8MHz IF strip that he’s used in other projects. The VFO is a AD9913 DDS controlled by a Z80 microprocessor

The 8 Pole filter is now in the Transceiver and working great, it has the same BFO frequencies as the seven pole filter. Here’s the old 7 pole version.

The Alignment of the completed module is very simple.First connect and adjust the S Meter as suggested in the theory text (Must be in RX mode) and then connect a low level 8.000 Mhz RF signal source to the input.(you can use the BFO module as the signal source (CW Mode) with a switched step attenuator) adjust the output so the meter just moves, then adjust all of the RX Pi networks for a peak in meter deflection, as the meter deflection increases reduce the RF input.

Schematics diagram are available: read more

Home-Made KW-Transceiver

Schematics diagram for this homemade transceiver available: read more

DC7 home made Transceiver

The DC7 is the 7th in a serie of home made transmitters/ transceivers I have built over the years : it is a high performance H.F transceiver.

The receiver is a single conversion one using an 8 MHz IF : I have chosen this approach while most present commercial transceivers feature multiple conversions because of less potential birdies generation and also because the DC7 is a ham band only equipment.

The DSB signal produced by a NE602 balanced modulator is connected to the SSB 12 poles filter followed by an ALC circuit and the transmit mixer. The PA uses a push pull of 2SC1969 in a circuit inspired by the Elecraft K2 one. Classic low pass filters are connected between the PA output and the antenna connector.

Schematics diagram are available: homebrew transceiver

Homebrew transceiver – ei9gq

This page will describe the construction of a multi band SSB transceiver for 80M, 40M, 17M, 10M

Simplified Block Diagram

Transceiver band pass filter

I.F. Amplifier

AGC – automatic gain controller: On a quiet frequency the output to the IF amplifiers is about 6 volts. When the receiver is tuned to a strong signal, the signal from the audio pre-amp is amplified by the first BC109 transistor, then converted to a slowly changing DC voltage by a voltage doubling rectifier. This DC voltage is inverted by the second BC109. The voltage at the collector of the second BC109 will decrease as the received signal gets stronger. This voltage is applied to gate 2 of the IF amplifiers. The output is also used to drive the signal meter. I used a 50 microamp moving coil meter. The 10K pot is used to zero the meter. The 100K pot sets the meter deflection

Frequency Display And Vfo Stabiliser

Schematics diagram are available: read more

A QRP SSB Transceiver by WB9IPA

The synthesizer consists of the famous Analog Devices AD9850 DDS chip followed by a pair of D-type flip flops which form a quadrature divider. The AD9850 generates a signal in the range of 0 – 41 MHz which is then divided in the quadrature divider to give four outputs in the range of 0 – 10.25 MHz.

The final design would have the following goals:

• Cover the 160, 80, 60, 40 and 30 meter bands.
• Be designed primarily for SSB operation.
• Have a “strong” receiver that would be overload resistant.
• Transmitter output power would be in the 5-10 Watt range.
• Use components that were readily available from suppliers accessible to anyone in the US.
• Make extensive use of surface mount technology (SMT).
• Utilize the “phasing method” of unwanted sideband suppression.
• Utilize a Direct Digital Synthesizer (DDS) for frequency control.
• Be a direct conversion topology.
• Meet FCC requirements for spectral purity of emissions.

The schematic of synthesizer with AD9850

Schematics diagram are available: read more

HF Transceiver by I6WJB & I6YPK

The transceiver is the result of numerous workhours of Pierluigi (I6WJB) and myself (I6YPK). It has been built in two specimens. It is running since several years in our stations and has given us big satisfactions. The presence of the microprocessor allows to do all those operations that are usually not possible on an RTX with analogic VFO, and therefore I have included a lot of commands like: double VFO, RIT, memories, possibility to operate SPLIT, bottom CW, ecc.

Features:

• 1 Hz Step Frequency Synthesizer – The Frequency Synthesizer is a combination of DDS (AD7008 Analog Devices) and PLL
• Wide Dynamic Range – The receiver employs double balanced diode mixer (designed by I6WJB)
• Remote operation – Via RS232 Computer interface
• Tx – Rx Frequency: 100 KHz ~ 30 MHz
• Emission modes : USB, LSB, CW, AFSK, (AM only in Rx mode)
• Tuning steps : 1 / 10 / 100 / 1000 Hz
• L.O. Phase Noise : -90 dBc at 1 KHz
• Intermediate frequencies:70 MHz crystal filter (15 KHz bandwidths), 2,5 MHz crystal Filter, 48 KHz mechanical filter
• Sensitivity (14 MHz) : SSB (3,1 KHz bandwidths) 0,7 uV x 12 dB S/N (pre off), SSB (3,1 KHz bandwidths) 0,4 uV x 12 dB S/N (pre ON)
• Noise Figure: 13 dB PRE-OFF / 8 dB PRE-ON
• AGC control: Less than 3 dB rise in audio output for 120 dB signal increase from noise, floor (PRE-OFF)
• Audio power : 3 watts into 8 ohms
• Spurious Rejection : > 70 dB
• 3rd Order Intercept Pt. : + 25 dBm
• Dynamic range : 120 dB (RF pre-amp OFF)
• Output Power : SSB / CW adjustable 10 Watts (class A) into 50 ohms

HF Transceiver by I6WJB & I6YPK

Schematics diagram are available: homemade transceiver

A Simple Dual Band SSB Transceiver

A dual-band transceiver with a crisp receiver and a clean SSB signal is described.

We decided to pursue the following rules in designing this transceiver:

• Use what is easily available
• Keep impedances and gain low
• Broadband
• Modest cost
• No PCB
• Quality over quantity

Schematics diagram are available: read more

g3tso 160m transceiver

This project was successful, but cumbersome for mobile operation; the next stage of evolution was to use the driver and PA stages as the basis of a single band 160 metre transceiver. The addition of a suitable exciter and VFO were now required. The exciter is based on a kit designed by G4CLF using Plessey SL1600 series ICs with a 10.7 MHz IF.

10.7 MHz Transceiver Unit

Schematics diagram are available: 160m transceiver

Eighty Oner by sp5ddj

Eighty Oner is based on Direct Conversion receiver and VXO transmitter. Receiver is very sensitive and BCI filtering is excellent.

The concept is based on Wayne’s NB6M idea and attempt to find an answer – “How low can we go with VXO”.

The range of RX is 3490 kHz – 3578kHz. TX range is smaller (due to poor transmitter’s tone), but covers 3545kHz – 3578kHz. Good enough for QRP.

Schematic available: Eighty Oner

GW4ALG’s 80 m QRP Radio

The home made transceiver covers 3.5 to 3.6 MHz and is CW only. It has the following features:

• Full break-in operation
• AGC;
• Clarifier/Independent Receiver Tune (IRT)
• Crystal ladder IF filter (about 600 Hz bandwidth)
• SWR indicator (LEDs for foward/reverse power)
• Side tone generator
• 12 v operation

Block/Schematics diagram are available: read more

80m SSB & CW QRP superhet transceiver by s57nan

The 80m SSB & CW transceiver design is based on an already proven concept used in ATLAS amateur transistorised transceivers from 70’s. The “two-mixer + 1 XTAL filter” design uses the 1st mixer as front-end mixer on receive as well as SSB modulator on transmit.

With the exception of both oscillators, diode switching matrix and TX PA, all transceiver units are placed on one main PCBoard. The on-board audio output stage is capable of driving low-impedance stereo headphones. There is separate BFO / VFO PCB which also includes the diode switching matrix. Unlike other my transceiver designs this one is built mostly using classical (wired) components.

Block/Schematics diagram are available: read more

The ROSE 80 CW Transceiver (N1HFX)

This ROSE boasts the following features:

• Full 5 watt output using a power MOSFET final that is resistant to high SWR and thermal runaway. This final is very efficient and runs much cooler than traditional bipolar designs.
• Highly sensitive and selective superhetrodyne receiver with plenty of audio to drive a speaker. About 100 Khz of tuning range is provided through a varactor diode along with a switchable RIT control.
• Full break-in keying with a unique T/R switching system.

Schematics diagram are available: read more

3.5MHz 10W SSB transceiver with 14 transistors

In every weekend, I go to the top of the mountain and make local expedition with 50MHz SSB. In week day , after job, I operate 7MHz CW on my shack. But in these days, on the 7MHz , my signal skips out from Japan and I can not contact any station after 10 o*clock. Therefore I decided to make 3.5MHz SSB and CW rigs. I will show you my SSB rig on this page and I will show you CW one on the next page. With each gears, I could contact about ten domestic stations.

Schematics diagram are available: read more

Unichip 80m transceiver

This is a homebrew 80m transceiver in one chip, the CA3086 transistor array.

Schematics diagram are available: read more

Homebrew 40m CW Transceiver

• Freq. range 7.000 – 7.030 MHz
• RX part Superheterodyne with RIT and side tone
• LO-OSC super VXO with two 11.5412 MHz X’tals
• IF filter 3-element 4.5MHz HB ladder X’tal filter, BW=400Hz
• TX part Carrier-OSC/MIX TA7358AP with offset freq.

Schematic available: Homebrew 40m CW Transceiver

Forty2

Here is the latest model in the series of Forty, prototype version complete, and definitive. It cover 7000 a 7300 khz. It incorporates the latest changes to make it more efficient.

Here are its features:

• synthesizer with 10, 1 and 0.1 kHz step using a microcontroller
• RIT and split
• S metre with LED bar graph
• Compressor modulation of high quality.
• BF increased power (3 watts RMS).
• 5 watts RF power efficient.

Forty2 project

Schematic available: Forty2

Forty Oner by sp5ddj

This name and part of schematic are taken from 49′er where 40 represents the band, and 9 is 9V battery to supply the rig.

“Forty – Oner” means that one watt is produced on 40M band. The idea to build simplest and smallest working rig came to my mind after hours of surfing the Internet QRP resources.

But the simplest not necessary means comfortable to operate.

Technical data and assembly

• Supply voltage: Typically 13,8V. Less voltage – less output power. Should work down to 7,5V.
• Frequency range: 7000,8 kHz – 7037,4 kHz ( QRP calling frequency in Europe is 7030 kHz )
• TX output power: Theoretically up to 1W, in practice 0,7 W or less. Use small heatsink on 3866.
• Frequency stability : Very good even on the edge of span, but FET follower is a must. Crystal’s cases shall be soldered and grounded. Use 10k helipot instead of ordinary potentiometer if you don’t need fast tuning.
• QSK&Sidetone : Very useful but you must be aware of “knocking” into a speaker due to RF detection in AF amplifier stage during transmission. Grounding pin 3 of LM386 helps but this require additional transmit/receive SPST switch (couldn’t find the room for this ). Sidetone needs adjustment of signal level.
• RX sensitivity: Improved by adding serial R&C on pin 1 of LM386.
• RX audio: Excellent if you spend some time tuning AF filter. Small speaker is enough.
• Antenna output: Calculated for 50 ohms. For wire antennas use ” Mini ATU “
• Workload: Two full week-ends If you have all components, case and your wife’s agreement. Use universal board for digital applications.
• Efficiency report: Using Inverted Vee antenna I ‘ve made several European’s QSOs with RST 559 or better.

Schematic available: Forty Oner

PQD5 – 40 meter SSB QRP transceiver

This transceiver was conceived as a power-efficient, small, lighweight unit to be carried in the backpack, along with antenna and battery, for use during trekking and mountaineering trips.

Specifications:

• Frequency coverage: 7.0 to 7.3 MHz
• Operation mode: LSB
• Frequency stability: 100 Hz in 30 minutes, worst case
• Power supply voltage: 12 V nominal, while 10.5 to 14 V is OK
• Current consumption: RX: 30 mA at no output, 33 mA average, 90 mA at max output
• Current consumption: TX: 270 mA at no output, 500 mA average, 1 A at max output
• Meter readings: RX signal – TX power – Battery voltage

PQD5 – 40 meter SSB QRP transceiver

40 meter SSB QRP transceiver schematics

Block/Schematics diagram are available: read more

40 meter QRP Transceiver – w8zr

This semi-homebrew QRP (low power) CW transceiver is based on the ARK-40 transceiver kit, by S&S Engineering. As supplied by the factory, the ARK-40 uses thumbwheel switches to change frequency.

QRP transceiver, showing virtual “bandspread dial” on the LCD display. When the main tuning knob is turned, the dial scrolls across the band in 1 kHz increments. Pressing the tuning knob changes the display to digital readout, and the tuning rate slows to 100 Hz resolution (below).

This is the assembled synthesizer board from the ARK-40 transceiver kit. This board accepts the BCD code from the microcontroller.

read more

h3>7MHz CW transceiver

7MHz is best band in order to make domestic QSO. But 7MHz ssb is too crowded to make QSO with QRP. Therefore 7MHz CW is best way to make domestic QSO. I will show you my handmade 7MHz CW QRP transceiver. About receiver.. ..** This is a normal single conversion super heterodyne. ** This machine has 300Hz crystal filter. Yes, it is super-narrow filter. I made it with 3.57MHz croma-crystal for TV. ** Two oscillator is connected to each DBM ( double balanced mixer). Because the load of oscillator is not changed in transmit and in receive , the oscillated frequency cannot change.

Block diagram

read more

The simple 7MHz CW transceiver made with Motrola MC3362P

7MHz CW transceiver by using the IC for the narrow band FM double super receiving circuit, MC3362P

MC3362P is an IC for the narrow FM double super heterodyne receiver. This contains two sets of combinations of the mixer and the local oscilator to change input frequency to 200MHz into 1stIF (10.7MHz), 2ndIF (455kHz). Each mixer has conversion gain before and after 20dB respectively. Moreover, a 1stLO circuit builds in a variable capacity diode, and only connects a coil for the tank circuit with the outside, and it can compose a VFO circuit. But, I add the silvered mica capacitor of 180pF in the outside to make it VFO of 5MHz band with this transceiver, too. Because 7MHz CW band is narrow, I can secure the variable range that even such a combination is satisfactory as to this. And, the part which I am not using with this transceiver is omitted in the inside block diagram of the IC. It is a part only for FM such as the IF limitation amplifier and the quadrature detection.

read more

Homebrew 30m CW Transceiver

Characteristics:

• Freq. range 10.100 – 10.140 MHz
• RX Superheterodyne with RIT and side tone
• LO-OSC super VXO with two 48.4611 MHz 3rd O.T. X’tals(Fund. freq. is 16.153 MHz)
• TX Carrier-OSC/MIX TA7358P with offset freq.
• Tx Rx switch Two ordinary Si diodes back-to-back in RX antenna and audio mute with 2SK168

Homebrew 30m CW Transceiver

114MHzSSB 10mW transceiver OZL type

Characteristics of the “OZL type” are as follows:

• Single conversion super.
• Using two DBM-s as modulator and converter.
• Modulator DBM is used as demodulator in receiving time.
• All amplifiers are used in transmitting and receiving time.
• Case is second use of my failed or useless machine.(This time I used my useless old 10W 7MHz transmitter.)
• All decals are done with the “Magic ink”. Very simple way!
• Normal “OZL type” uses 12V DC power from cigar lighter of the car. But in this machine I used 20V DC from my DC power supply. The reason of my choosing high voltage are as follows. One reason is in order to press the variable capacitor of the VXO oscillator for it’s minimum capacitance and to get the highest frequency and to get the wide frequency range of the operation. Second reason is to use 24V relays instead of 12V relays. I got these 24V relay with only 10 dollar for 10 peace. It was cheep Junk but super micro molded type can be used for 430MHz. The name of these relays are G6H2-24V. Maker is OMRON company. Third reason of high voltage is in order to get 10W power easy with good linearity. In my experience it is difficult to get 10W with 12V power pupply.

Schematic 14MHzSSB10mW transceiver

The 1 watt 20 meter QRP transmitter with VXO

This is a nice QRP transmitter that can be used in combination of one of the simple receivers.
Normally these designs have only two transistors: one is the X-tal oscillator and the second the final amplifier. A good example is my first QRP rig that is also described somewhere on this site. Here the VXO (Variabele X-tal Oscillator) has a tuning range of 16 kHz. This VXO is buffered with an extra driver stage for a better frequency stability and a varicap diode is used instead of a variabele capacitor. An extra transistor is added for keying the transmitter with a low keying current.

The simple QRP transceiver is used in combination with an old SSR1 shortwave receiver. It is not difficult to make QSO’s with it while using a simple inverted Vee dipole antenna with the center at a height of 4 meters. This 1 watt QRP transmitter is all you need to be a radio amateur and to collect a shoe box with QSL cards! The total frequeny range is 16 kHz but even the small 4 kHz range without Lx//Cx is already more than enough for a lot of contacts. The RF output power is 1 watt at 12 VDC and 1.5 watt at 13.8 VDC.

More info

Homebrew 20m CW Transceiver

• RX part Superheterodyne with RIT and side tone
• LO-OSC 2SC2458, super VXO with two 11.059 MHz X’tals Frequency doubled
• IF filter 4-element 8MHz HB ladder X’tal filter, BW=500Hz
• T/R switch – Full break-in – Two PIN diodes Back-to-back in RX antenna and audio mute with 2SK168

More info

oz2cpu 20m transceiver

The DDS 128Mhz Clock frequency is now generated with a VCO and PLL locked to the 12.8Mhz TCXO (Temperature Compensated Xtal Ocillator)
The same PLL and VCO IC also generate 10.7015 Mhz (the BFO freq for USB). It cal also generate the LSB signal, when in LSB mode.

20W SSB power amplifier

AGC Tester – This tester can switch a HF signal ON / OFF fast.
Controll it with a 1 Hz square signal, then look on your scope what happens with the audio from the reciever on test.
Adjust your HF signal generator to 0dBm, then the input signal will change from -120 dBm to 0dBm
Make sure to add a “wall” with a small hole arround each diode, this will give good HF isolation
If this tester is only to be used at HF, then just use 1N4148 diodes.

Homemade DDS

Schematics diagram are available: read more

BITX20A transceiver

This blog or journal is focused on the assembly of a prototype BITX20A QRP SSB Transceiver kit from Hendricks QRP Kits and is part of a prototype evaluation process leading toward general availability of the kit. The purpose of the blog is for record keeping of assembly steps in a form that can be used as a project construction manual.

More detail about the BITX20 transceiver can be found at http://www.phonestack.com/farhan and on the BITX20 group forum at Yahoo Groups (http://groups.yahoo.com/group/bitx20/

BITX20A schematic

Schematics diagram are available: BITX20A transceiver

BITX – An easy to build 6 watts SSB transceiver for 14MHz

BITX is an easily assembled transceiver for the beginner with very clean performance.
Using ordinary electronic components and improvising where specific components like toroids are not available, It has a minimum number of coils to be wound.

There are a couple of things you should know before you start assembling the circuit:

• The same amplifier block is used throughout
• The receiving IF amplifier between the filter and the product detector is coupled to the product detector using a 100pf (not 0.1uf).
• Power output : 1W
• The microphone is directly coupled to the amplifier
• The pre-driver is built onto the main board.

Schematics diagram are available: read more

Pocket sized 20m CW QRP transceiver – tested on 17m/20m/30m/40m

The goal was to make a gear that would be based on a superhet receiver, would measure less than 10cm x 10cm x 5cm and would include a digital frequency read out. The transceiver should also be “bullet proof” against the strong HF broadcast signals, highly present in the Central European region. The final result was two transceivers built, one for 20m and one for 30m band.

Homemade Transceiver s57nan

Block diagram

Schematics diagram are available: read more

21MHz 2W DSB transceiver

21MHz 2watter double side band simple transceiver. The circuits is constructed on the cover of the case with the connectors and switches. This construction is easy to make maintenance. The audio signal made by microphone is amplified by LM386. It is injected on the IF port of the DBM. Oscillator unit makes the 21.27MHz RF signal. It is injected on the LO port of the DBM modulator. This DBM is called as a High level DBM. This type DBM can deal the power more than 100mW.

Oscillator unit

21MHz 2W DSB transceiver

3 transistor 21MHz CW transceiver

I made CW 1W transceiver with only three transistor. I could make QSO by this machine with Saga, Asahikawa (domestic far distance city),and Indonesia and Taiwan. .. See fig1! Transmitter is three stage. Oscillator makes 10.5MHz signal by VXO oscillator. Diode doubler multiply it to 21MHz signal. Two stage amplifier makes its signal to 1W. The final AMP is keyed. .. Receiver is constructed by a direct conversion type. Antenna signal is amplified with RF-AMP. On the other hand VXO and doubler makes 21MHz beet frequency. The diode-single-balanced-demodulator exchanges the radio frequency-signal to audio-signal. Audio-AMP is constructed by two stage AMP. And the RF and AF AMP is made by reflex construction. I must turn the rit switch, when I receive the signal of DX station. But when I make Zero-tune , I do not need touch it. .. You can see the many T-R switches on the circuit drawing. I used two relays for this purpose..

Block diagram

Schematics diagram are available: read more

21MHz 1W SSB and CW Transceiver

On these days the HF condition becomes better and better. I have waited that for this five years from last cycle. It is 6 jun 1998 today. Therefore I decided to lift new antenna for 21MHz in my house. Yes, It is quite big sloping dipole and I made this new transceiver to operate CW and SSB with one box of machine.

Block diagram

Schematics diagram are available: read more

21MHz DSB transceiver

In these days cycle 22 becomes stronger day by day. I want to make QSO in 21MHz like the cycle 21, about 6 years ago. I made simple DSB( double side band) transceiver. One of my friend made the same rig and completed it. Therefore I think that this page has good re-productivity. There is the DBM(double balanced mixer) on the center of this circuit. In transmitting time, the audio signal is injected on the If port of DBM. The 21MHz CW signal is injected on the Lo port of DBM. Therefore the DSB signal is producted on the Rf port of DBM. In this machine, the DBM is constructed as the high level type. And it is drived with 360mW CW. Therfore it can porduct 160mW DSB signal directly. Therefore I can product 2W signal with only single stage Rf amplifire.

Block diagram

Schematics diagram are available: read more

Idaho SSB 75 Meter Transceiver, WA7JHZ

WA7JHZ provide some of his homebrew transceiver schematics and experimentally developed projects.

Both receive and transmit bandpass filtering are done by the same half-pi BPF. The diode pair in the mic circuit reduce the “chirp” that occurs during the R/T transition. Additional BS170s could easily be used to mute both the mic and audio instead of the R/T switch directly. These BS170s would be controlled by the +R and +T voltages on their gates while their drains would be tied to 1) the mic circuit between the two coupling capacitors and 2) pin number 1 (audio in) of the LM386 (BS170 sources to ground). Additional power output (perhaps 60 mW) could also be attained by connecting the RF output transistor’s collector choke (10 uH) to a 9 V supply instead of the 5 V. Additional biasing current might also be required for this change.

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Pocket-trx

This page is written in Russian language, but Google translate it to English

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