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