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Amplifier Circuits: 
RF (Radio Frequency)

RF Amplifiers:  #'s - C      D - K        L - R       S - Z

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Last Updated: November 30, 2017 07:37 AM

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A/a-rf.htm    Page 13

SCA Adapter -  For Advertisement Free Background Music on FM. __ Designed by G.L. Chemelec

SCA Subcarrier Demodulator for FM broadcast stations -  SCA' stands for 'Subsidiary Communications Authorization', and is a technique which allows FM broadcast stations to add up to two 'invisible' medium-quality audio channels to their normal stereo transmission.  It's widely used in the USA and Australia for distributing background music and broadcasting for ethnic / disabled / special interest listeners.  Normally the only way to listen to these additional channels is with a special purpose receiver, but this little board will allow most standard FM radios and tuners to produce an SCA audio output. __ Designed by Bob Barker, not the TV Host

Scanning Voltmeter with Minimum Mass Wireless Coupler -  ATMega8  A 10 bit scanning voltmeter with a Minimum Mass Wireless Coupler, based on the ATMega8.  Range to the Minimum Mass Base Unit is 10 to 15 cm.  If the voltmeter is battery operated, it can be floated from ground. __ Designed by Dick Cappels

Send Morse on your VHF Rig -  MorseBox consists of two stages. These are a tone oscillator and a transceiver control/timing circuit. __ Designed by Peter Parker VK3YE

Sensitive LW/MW/SW Shortwave general coverage receiver -  This is a compact three transistor regenerative general coverage receiver with fixed feedback.  It's based on the principle of the ZN414 only it can handle higher coverage.  The sensitivity and selectivity is relative good (especially on the LF and MW bands) as can be expected with this "simple" design. __ Designed by Guy Roels ON6MU

Service Monitor allow your Scanner to measure Deviation -  For creating a COS signal on radios that don't have one.  This is a VOX circuit that uses a FET as the input amplifier to avoid loading down the source. __ Designed by Tom Alldread VA7TA

Shortwave received -  Schematic only __ Designed by Petr   Prause, OK1DPX

Simple  RF Based Code Lock -  This simple radio frequency (RF) based code lock incorporates a pair of 433MHz ready made RF transmitter and receiver modules.  It is a remote-controlled and code-protected locking system.  The code is__ Electronics Projects for You

Simple  RF Power Amplifier -  Here is an inexpensive but powerful RF power amplifier for the 40m (7MHz) band.  The circuit accepts only 20-30mW RF power and amplifies it to the wattage level.  So its input__ Electronics Projects for You

Simple Circuit 2.4 GHz SWR Meter -  Simple way to tune wireless LAN antennas using an oscilloscope. __ Amateur Radio circuits from Green Bay Professional Packet Radio

Simple Circuit 3 Transistor Audio Amp 50 Milliwatt -  Here is a little audio Amplifier similar to what you might find in a small transistor radio __ Designed by Bill Bowden

Simple Circuit ADS-B aircraft transponder Decoder based on a PIC18F2550 microcontroller -  This project aims at creating a hobbyist ADS-B receiver with on the shelves components.  It uses a PIC18F2550 to decode ADS-B pulses received by a modified SAT tuner and demodulated by an Analog Device AD8307 log amplifier.

Simple Circuit AF-oscillator / signal generator using paIR on 2N2222 transistors -  Schematic only, no circuit description __ Designed by Guy Roels ON6MU

Simple Circuit Crystal Radio -  The crystal radio gets its name from the galena crystal (lead sulfide) used to rectify the signals.  A "cat's whisker" wire contact was moved about the surface of the crystal until a diode junction was formed.  The 1N34A germanium diode. __ Contact: Charles Wenzel of Wenzel Associates, Inc.

Simple Circuit CW identifier for a FM repeater (PDF) -  Not in English __ Designed by Aleksander Stare

Simple Circuit Dual Band SSB Transceiver (20/40 meters) -  Circuit Only __ Designed by Ashar Farhen

Simple Circuit home made ADS-B receiver that takes IF from a Modified receiver -  The new project uses old analog satellite receiver tuners that have to be modified so that the AFC is disabled and the AGC usually set to maximum gain.  The output is the 480MHz IF signal. __ Designed by Edward John Cardew

Simple Circuit Op-Amp Radio -  This is basically a crystal radio with an audio amplifier which is fairly sensitive and receives several strong stations in the Los Angeles area with a minimal 15 foot antenna.  Longer antennas will provide a stronger signal but the selectivity will be worse and strong stations may be heard in __ Designed by Bill Bowden

Simple Circuit Radio Control from Junk -  Here we are going to make a simple radio controlled device using supplies from your local dumpster.  This project should cost less than a dollar to make.  If you spend more than a dollar on this project, you need to dig more. __ Designed by sixmhz @ yahoo.com

Simple Circuit Repeater Fan Controller -  an 18 kB PDF file __ Designed by Robert Shepard KA9FLX

Simple Circuit RF Noise Source -  A noise generator with a wideband output signal is always handy to have around when you’re adjusting receivers and other types of HF equipment.  The noise generator circuit described here uses the base–emitter junction of a transistor (in this case a BF199) operating under reverse biasmust register on this site __ Designed by Published in Elecktor July/Aug, 2010

Simple Circuit RF Power Meter -  Here is a simple set up which will enable them to measure the out put power of their transmitter. All that they require is a good multimeter which has a sensitivity of 20k ohms/4 Watts which is adequate for low power transmitters.

Simple Circuit RF Power Meter -  Here is a simple set up which will enable them to measure the out put power of their transmitter.  All that they require is a good multimeter which has a sensitivety of 20k ohms/4 Watts which is adequate for low power transmitters.  

Simple Circuit RIT based on a 2N7000 FET -  The diagram below shows the simple RIT circuit that I added to my 15M Cub. The circuit is certainly not original, but I don't recall where I first saw it. A 1N4004 is used as a "tuning diode" – reverse voltage applied to it via the 2K pot varies it capacitance. (Do not use a 1N4001, …2 or …3 – they won't have sufficient capacitance range.) __ Designed by Larry East, W1HUE

Simple Circuit Time-Difference-Of-Arrival RDF -  This T.  D.  O.  A.  RDF set is built into a die-cast Pomona box.  I built it in October, 1989.  As you can see from the photo, it has held up to lots of abuse as it gets knocked around in my RDF bag. __ Designed by Joe Leggio WB2HOL

Simple Circuit Two-transistor Radio -  Here is a simple radio that was designed to minimize unusual parts; there isn't even a detector diode! The sensitivity isn't as high as the one-transistor reflex but the simplicity is attractive.  Strong stations will provide plenty of volume __ Contact: Charles Wenzel of Wenzel Associates, Inc.

Simple RF Preamp -  I built this RF preamp from junkbox parts. The common-gate circuit provides an input return loss of > 18 dB from 88 to 108 MHz. The corresponding mismatch loss is < 0.07 dB. I could not find a recommended source impedance for lowest noise figure. I went for a good match instead since input mismatch loss directly degrades the noise figure. __ Designed by Brian Beezley K6STI

Single transistor receiver for SSB, CW, AM using a VHF dual gate MOSFET -  Single transistor receiver for SSB, CW, AM __ Designed by EI9GQ homebrew radio

Smart VOX from Jet Propulsion Laboratory-Nasa -  For creating a COS signal from a radio that doesn't have one.  This circuit was developed to control the retransmission of NASA Select audio over JPL's W6VIO repeaters. __ Designed by Randy Hammock KC6HUR and Jan Tarsala WB6VRN 

Smooth Tone Clickless CW Sidetone Generator -  This circuit is about as good as it gets for generating morse code tones.  It may be used as a code practice oscillator, a tone generator for a keyer, a sidetone oscillator for a CW transmitter or an audio Modulated CW (MCW) generator for an FM transmitter or repeater __ Designed by G. Forrest Cook

Someone say "6 meter duplexer" ? -  A comprehensive conversion of a lowband pass cavity to BpBr __ Designed by Jeff DePolo WN3A.

SSB ADAPTOR -  Build this simple adaptor to receive single side band SSB on short wave AM receivers

SSB Tramsceiver, Exciter Board -  Now that people are getting married, and having babies on the internet, isn't it about time someone designed and built an SSB rig on the net?.  The rig will be built up from various modules, starting with the SSB exciter board.  The first prototype board has been built and tested on the bench but not on air.  The resulting SSB signal looks good on the scope, and sounds ok on a monitor receiver. __ Designed by EI9GQ homebrew radio

StarTech CM108 based USB sound adapter conversion article -  For AllStar (Asterisk) VoIP __ Designed by Kevin Custer  W3KKC

Subcarrier Adapter -  Listen to those hidden FM transmissions. __ Designed by Tony van Roon  VA3AVR

Super 80 ultra-Simple Circuit SSB receiver for 3.5 MHz a basic superhet -  amateur radio Schematic only __ Designed by Peter Parker VK3YE

Superhet/Direct Conversion AM receiver for 181.818 kHz  -  This is a description of an experimental AM receiver for VLF.  It is crystal controlled to receive 181.818 kHz   (more or less) and operates as either a single conversion superhetrodyne or a direct conversion receiver.  The bandwidths are expected __ Designed by Dick Cappels

SW30+ 30 Meter CW Transceiver -  SummaryThis 30 meter CW transceiver was built as part of an internet Manhattan-style construction course conceived and taught by my friend Chuck Adams, K7FO back a few years ago.  The basic rig is a Small Wonders Lab SW30 (Dave Benson, K1SWL design)  with some enhancements, most notably, a coupled resonator filter in the receiver front-end, a 4-pole crystal filter (original design had 3-poles), and an audio amplifier suitable for driving a speaker. __ Designed by Jim Kortge, K8IQY

Switching Diode Frequency Doublers -  Ordinary fast switching silicon diodes, special fast recovery junction diodes, schottky barrier diodes, varactors and even old-fashioned germanium diodes or vacuum tubes may be used to construct signal powered frequency doublers __ Contact: Charles Wenzel of Wenzel Associates, Inc.

SWR bridge covering HF to VHF -  Schematic only __ Designed by Guy Roels ON6MU

Synthesized, Handheld, 2 meter VHF receiver with computer control -  This little handheld VHF FM receiver was designed as a demonstration project of using a PIC microcontroller to drive all the functionality of a complete receiver.  The receiver features an untuned RF input stage, followed by a double conversion super-hetrodyne receiver.  The frequency tuning is accomplished by using a rotary encoder that the PIC reads and translates into programming commands for the 1st LO synthesizer.  Tuning steps of 5, 10 and 100 kHz may be selected. __ Designed by Steve Hageman

A/a-rf.htm    Page 14

Telephone Line Filter / Protector -  To build a circuit that will help protect your equipment from lightning strikes on the phone line.  This circuit was actually designed to reduce or eliminate a very local broadcast AM radio stations signal from bombarding my parents telephone line, however it also turned out to be a really good lightning protector. __ Designed by Kevin Custer  W3KKC

Terminal Interface with Minimum Mass Wireless Coupler -  AT90S2313 This is a Minimum Mass Wireless Coupler that connects a terminal, or PC running terminal software, to other Minimum Masss Wireless devices by means of a 1200 baud data channel at 181.818 kHz. __ Designed by Dick Cappels

The Daiwa PS-304 power supply gets Anderson PowerPole Connectors -  A step-by-step procedure that increases the usability of a good power supply. __ Designed by Kyle Yoksh KØKN 

The F.E.D. Detects digital RF signals -  The F.E.D.  (Frequency Emissions Detector) will, of course, detect anyone's cell phone, so the detector really responds to just about anybody with more than two pennies to rub together.  Most phones occasionally transmit short bursts to the nearest cell tower, even when the phone isn't in use, so a typical 21st century loiterer will eventually set off the detector.  On the other hand, a deer can stare at it for an hour with no effect.  Let's face it, even most burglars emit digital signals these days.  So, in a sense, the F.  E.  D.  is a human detector.  With that in mind, consider using the output to activate a digital camera or video recorder to capture a record of the prowlers.  A recorded barking dog or, one of my favorites, a recording of police radio traffic will scare off most crooks.  Add some hidden flashing red and blue lights to the police chatter and the culprits will actually run away. __ Contact: Charles Wenzel of Wenzel Associates, Inc.

The Jet Propulsion Laboratory-"Smart VOX" -  For creating a COS signal from a radio that doesn't have one.  This circuit was developed to control the retransmission of NASA Select audio over JPL's W6VIO repeaters. __ Designed by Randy Hammock KC6HUR and Jan Tarsala WB6VRN 

The Journey to Forever--Crystal Radio -  You can make a crystal set out of almost anything -- any small box, or just a bit of wood, or a frisbee or a deodorant dispenser (actual examples), or these (recommended for beginners): __ Designed by Keith Addison

The Repeater Builder's Friend -  A device to help to you fix your repeater or program your controller __ Designed by Matt Krick K3MK

Tiny Tuned Loop Antennas for the Minimum Mass Wireless Coupler -  Loop Antennas are considered to be "samall" when their diameter drops below about 1/10 of the wavelength they are intended to be used at.  In this case, I use the term "Tiny" because the antenna's diameter is about 1/30, 000 the wavelength, and at 5.5 cm __ Designed by Dick Cappels

TL431 Crystal Radio Amplifier -  Here is a simple audio amplifier using a TL431 shunt regulator.  The amplifier will provide room-filling volume from an ordinary crystal radio outfitted with a long-wire antenna and good ground.  The circuitry is similar in complexity to a simple one-transistor radio but the performance is far superior.  The TL431. __ Contact: Charles Wenzel of Wenzel Associates, Inc.

T-Match ATU (Antenna Tuning Unit) -  A simple T-Match ATU.   I used silver plated copper wire for L1 and L2.  If you use enamelled copper wire, remove the insulation on one side of the coil, so that you can easily change the number of turns used for each band.  If you don't need to cover 160 Metres, L1 can be reduced to about 25 turns.  L2 is only used on 10 Metres. __ Designed by EI9GQ homebrew radio

Touch CPO -  touch operated code practice oscillator using popular timer IC555.  Practice Morse code in a different way

Transmitter FM 45W with valve -  The catering better it does not become at straight line from the network 220V but via transformer 220V/220V of isolation and safety 1AWhen does not exist the R3, the force of expense is bigger, but respectively is increased also the hum 50Hz, because the simplicity of designingThe control (Audio In) can become from a kasseto'fwno or other powerful source.  If it is microphone it will be supposed precedes amplifier so that it acquires a force of order of 8W roughly. __ Designed by Kyriakos Kontakos

Tuning VFOs with a PN-Junction -  Timing and oscillator circuit diagrams / circuit schematics

TV Signal Amplifier -  This is a small, broad band, signal amplifier which covers the frequencies from 40 to 900 MHz.  These frequencies include TV in VHF and UHF and also the radio broadcasting frequencies in the 88108 MHz FM band. __ Designed by © of this circuit belongs to smart kit electronics

TV Tuner Radio -  With this radio you can tune into anything from 40 to 900MHz!

Two Diode Odd-Order Multiplier -  It is often necessary to multiply the frequency of low noise oscillators without significantly degrading the phase noise beyond the theoretical 20 log (N).  Low noise frequency doublers constructed with Schottky signal diodes are readily available but higher-order multipliers often __ Contact: Charles Wenzel of Wenzel Associates, Inc.

Two Transistor Reflex Radio -  Schematic & PC Board, no circuit description] __ Designed by © David Hoult

A/a-rf.htm    Page 15

UHF Amplifier for 400 ~ 850MHz using a 2SC3358 transisor -  As shown in Fig range is a frequency of 400 ~ 850MHz UHF amplifying circuit.  Printed circuit For best performance and results, the circuit should be used by the silver tin processing.

UHF TV PreAmplifier -  This circuit is designed to work at UHF frequencies in the range 450-800MHz.  It has a gain of around 10dB and is suitable for boosting weak TV signals __ Designed by Andy Collison

Ultra-Low-Noise S-Band Amplifier -  06/04/12  EDN-Design Ideas Use capacitive reactance to save energy while holding a solenoid in the energized position.   Solenoid loads generally exhibit large hysteresis.  Application of the rated voltage actuates these loads.  Once they are in position, however, you can use a significantly lower voltage to thereafter reliably hold them on.  A lower sustaining voltage results in less heat production and higher efficiency. __ Circuit Design by Jessica MacNeil

Universal USB digimode interface supports CAT (Yaesu), CI/V (Icom) & RS-232 (Kenwood) units -  Microcontroller based electronic circuit __ Designed by Aleksander Stare

USB / CAT (CI-V) adapter tested with FT-8900, FTB-9800, VX-7R, VX-7, FT-817 & IC-706MkIIG -  Schematic only, no circuit description included. __ Designed by Aleksander Stare

Use an Astron power supply remotely? -  Don't run to the repeater site to reset the Astron anymore! (scroll down to the Reset Circuits) __ Contact: Mike Morris WA6ILQ

Using Part 15 Wireless Ethernet Devices for AM ateur Radio -  Hints, tips and rules for using off-the-shelf hardware for amateur radio Part 97 operations. __ Amateur Radio circuits from Green Bay Professional Packet Radio

Using the MC145158 PLL Frequency Synthesizer -  Simple overview and source code for the Motorola MC145158. __ Amateur Radio circuits from Green Bay Professional Packet Radio

Variable Bandwidth CW Filter -  As the sunspots return and DX propagation conditions to improve, the age old problem with QRM begins to show up on the amateur bands.  Fortunately, help is at hand.  The circuit in figure 1 is a variable bandwidth CW filter using two IC's.  The first IC is a 741 op amp used as an active filter and the second IC is a 386 audio amp IC.  This circuit connects to the headphone or speaker jack of your HF rig __ Designed by Radio Amateur Society of Norwich

Variety of receiver converter projects -  The FM broadcast band was moved immediately after World War II from its original spot just below 50 Mc to the present 88-108 Mc band.  Hallicrafters was one company to offer receiving converters for those who had the old FM radio sets.  The offerings included a one-tube converter that fits inside a console and draws power from the audio output tube socket (using an adapter).  

Versatile end-fed wire -  A piece of wire of almost any length can be used as an antenna on the HF bands.  However, just because an antenna can be made to work is no guarantee that it will perform efficiently.  This article will initially concentrate on the half wavelength of wire and its useamateur radio construction projects. __ Designed by Peter Parker VK3YE

Very High Gain Crystal Earphone Amplifier -  This simple, one-transistor amplifier provides a voltage gain over 1000 (60 dB) for driving a high impedance ceramic (crystal) earphone.  The high gain is achieved by replacing the traditional collector resistor. __ Contact: Charles Wenzel of Wenzel Associates, Inc.

Very Simple Circuit ADSB Receiver using a TV tunder to alLow reception of aircraft transponders -  With this design you can expect to get several 100 km range with a good antenna.  I use a home made J-pole with a single 32 Eurocent BFP420 transistor giving excellent low noise gain for very little money.  It can be bought like most of the needed components at Reichelt.  Many good quality (Kathrein for example) Satellite L band line amplifiers use this transistor and if you can get at least 12 Volts to the preamp they offer excellent performance despite being laid out for 75 Ohms.  I'll document the preamp later.  This is what you can get in Luxembourg with a clear view to the South for several kilometers __ Designed by Edward John Cardew

VFO from 2001 ARRL Handbook 4.20 -  Schematic only __ Designed by Jim Osburn, WD9EYB

VFO from 2001 ARRL Handbook 7.74 -  Schematic only __ Designed by Jim Osburn, WD9EYB

VHF 6 Meterband RF Amplifier -  Ham RadioAF AmplifiersSchematic __ Designed by Guy Roels ON6MU

VHF Receiver Converterer -  For Q1 and Q2 I used a pair of 3SK45 dual gate FET's.  Most VHF N-Channel dual gate MOSFETs should work fine.  I have used 3SK88, BF961, and BF981 FET's in this circuit.  If you decide to use a GaAsFET for Q1, you will probably need to use a Zener diode to reduce the drain voltage to a safe level.  L1 is 5 turns of 1mm copper wire, tapped at 1 turn,coil diameter 7mm, L2 and L3 are 5 turns each.  T1 primary is 9 turns on a Toko 10mm former (old IF transformer) T1 secondary is 2 turns.  The screening can and outer ferrite cup are not used. __ Designed by EI9GQ homebrew radio

VHF Receiver for Weather Satellites -  Build this compact 2-channel VHF FM receiver and pull in your own weather satellite pictures.__ SiliconChip

VHF Synthesizer -  This synthesizer was designed to drive a low cost VHF Aircraft Band receiver, but it has applications to any VHF radio in the 75 to 180 MHz band.  Low phase noise and reference feed through were also design goals.  The design was implemented in just a few day's and was fully tested and characterized.  Code was written to allow the synthesizer to be turned on and programmed, thus eliminating extra firmware support from the client. __ Designed by Steve Hageman

VLF Upconverter for Shortwave Receiver -  The schematic above is a simple up converter which I used in conjunction with a short-wave receiver to quite successfully to monitor solar flare activity a few years ago.  You can use a 3.5 or 4 MHz crystal for Y1 to up convert from about 10 KHz to 150 KHz to either 3.510 or 4.010 MHz respectively.  A long wire antenna was used here but a VLF loop antenna __ Designed by Radio-Sky Publishing

Wee Willy 75 Meter DSB Transceiver Project -  Many amateur experimenters stay in the familiar comfort zone of HF.  A small number venture into VHF, and even fewer devote time designing, building and operating for the UHF & microwave spectrums.  

Wide Band RF Amplifier for 10MHz-500MHz Input -  This paper describes an RF amplifier circuit which is suitable for the frequencies between 10MHz and 500MHz.  These kind of amplifiers are called wide band amplifiers. __ Designed by Yilmaz Kalafat, PE1PYJ

Wideband SWR meter -  A very simple design, cheap to built, does not require adjustment and works well! Depending on specific components and construction technique used, the upper frequency limit will be somewhere between 150MHz and 5GHz! __ Designed by Manfred Mornhinweg

Wideband VHF/UHF/SHF 22dB RF preamp with MAR-6 or MAR-8 (MSA-0885) -  The MAR6 (MSA-0686, 0685, 0885) is a high performance silicon bipolar Monolithic Microwave Integrated Circuit (MMIC) housed in a low cost, surface mount plastic package. 
This MMIC is designed for use as a general purpose 50 W gain block.  Applications include narrow and broad band IF and RF amplifiers in commercial and industrial applications. __ Designed by Guy Roels ON6MU

Wireless for the Bench Top ATtiny12 -  This section describes an experimental low power, low bandwidth data signaling system that was initially made to operate at 55 MHz (television channel 2 in the U.  S.).  Before operating a radio transmitter, find out what kind of transmitter operation, if any, is permitted in your locality.  Radio transmitter operation is a serious legal matter.  This design __ Designed by Dick Cappels

Wireless Network How-To -  Extremely detailed account of a Part 97 point-to-point 2.4 GHz wireless link. __ Amateur Radio circuits from Green Bay Professional Packet Radio

Xtal Radio Plans -  The radio in diagram 1 uses a variable inductor (coil) for tuning. The radio in diagram 2 uses a variable capacitor for tuning. Both radios are otherwise the same. The coil consists of 110 turns of 28 gauge enameled magnet wire wound on a 1.5" form. (toilet paper tube is easiest to get, but you can use something like plastic or other non-conductive material- hollow is best. D1 is a common 1N34 germanium diode- this is the detector. The crystal earplug is not the same thing as one would commonly find at your electronics parts store __ Designed by Keith Addison

Yaesu FT 736R Doppler Compensation -  The relative motion between a satellite and an observer causes a frequency shift known as the Doppler effect.  Doppler is well-understood and can be corrected automatically by satellite tracking software. __ Ken Ernandes

Zinc RF Amplifier -  Zinc negative resistance RF amplifier for crystal sets and negative resistance regenerative receivers. __ Designed by Nyle Steiner K7NS

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RF (Radio Frequency) Amplifiers:  #'s - C      D - K        L - R       S - Z


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