Simplified Modern Converter -  Here is as simplified design of the above converter.  This is much easier to build.    __ 

Single Chip Builds Tiny Aircraft Receiver -  09/25/97 EDN Design Ideas:  it's easy to become bored spending time in airports.  After all, you can do only so much work on a notebook computer with no reference material around.  So, relax and have some fun at the airport--build the tiny, single-chip, aircraft-band radio in Design by Steve Hageman, Hewlett-Packard, Santa Rosa, CA

Single IC forms Senesitive Modulated Light Receiver -  The circuit uses a very inexpensive C-MOS IC that is connected to a small photodiode.  Using a unique inductive feedback network, the circuit provides high sensitivity under high ambient light conditions.  it is a great circuit when you want to extend the range of an optical remote control transmitter. . . Circuit by Dave Johnson P.E.-June, 2000

Six Meter Converter   From the article "Junk-Box Converters for 6 and 2 Meters", by Rod Kreuter, WA3ENK, QST, January 1997, Page 33.   . . .  Web Author: David White, WN5Y

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

Soft-limiter forms basis of Simple Circuit AM Modulator -  09/03/07  EDN Design Ideas:  inserting diodes biased by reference voltages in the feedback loop of an op amp yields a soft limiter that you can use as the basis of an AM modulator Design by Herminio Martínez, Encarna García, and Juan Gámiz, Technical University of Catalonia, Barcelona, Spain

Solid State Fremodyne -  Electronic Australia's article from May 1970 on making a solid state version of the FremodyneThis is not the full article, but sufficient information is given for experienced constructors to duplicate the design __ Contact blehack @ yahoo dot com

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

SSB AF Filter -  This is a simple filter that restricts the LF response a little as well providing quite a heavy HF roll-off.  The prototype has enhanced a Yaesu FT101B that was only fitted with an AM iF filter.  The IC is an LM358.   __ Designed by Harry Lythall-SM0VPO

SSB Modulator covers HF band -  09/30/99 EDN Design Ideas:  in a previous Design ideas ("Modulator draws just 5 mA at 2.7V, " EDN, June 5, 1997, pg 111) , a phasing network combines with a MAX2452 modulator to form an single-sideband (SSB) modulator that accepts a 300- to 3000-Hz baseband signal and generates an SSB-modulated signal in the VHF range.  The author alludes to the possibility of improved performance if the modulator IC uses differential drive.  indeed, such performance is possible, but you need no additional components; in fact, you can achieve the improvement with a simpler circuit (Figure 1).   Design by Israel Schleicher, Bakersfield, CA - September 30, 1999

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

SSB/CW/AM receiver for 80m using one chip SA612 -  Ham Radio - V-U) HF AMPLiFiER - Schematic __ Designed by Guy Roels ON6MU

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

Sudden ionospheric disturbance (SID) receiver -  The AAVSO SiD Program consists of solar observers who monitor very low frequency (VLF) radio stations for sudden enhancements of their signals.  Earth's ionosphere reacts to the intense X-ray and ultraviolet radiation released during a solar flare.  The ionospheric disturbance enhances VLF radio propagation.  By monitoring the signal strength of a distant VLF transmitter, sudden ionospheric disturbances (SiDs) are recorded and indicate a recent solar flare event. __ Contact AAVSO SID Program

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

Superhet AM Broadcast Receiver -  Pictured above is a little AM superhetrodyne receiver that covers the
broadcast band from 550 Khz to 1650 Khz.  The  circuit employs the 8 pin
Signetics balanced mixer IC (NE602) which converts the incoming RF signal
to the standard 455 Khz iF signal and provides about 13dB gain __ Designed by Bill Bowden

Superregen Receiver for FM broadcast or Aircraft band AM reception -  This is the receiver I was bragging about on the Radio index page -- the receiver that is so sensitive it can hear the local oscillator inside a small transistor radio 30 - 50 feet away.  Build one of these little gems and you will be able to hear aircraft pilots many miles away with nothing more than a 24" whip antenna. __ Designed by Rick Andersen

Superregenative Receiver-VHF Tracking Receiver -  A superregenative receiver developed for tracking small FM transmitters but also tunes the aircraft band the top portion of the FM broadcast band.  Receives both AM and FM (107mHz to 135 MHz).  You can use this receiver with the  Beeping" FM transmitter" for a complete low cost radio tracking system.  The receiver is amazingly simple using only one transistor for the receiver section and one IC for the audio section. __ Designed by Jerry Baumeister

Superregenerative 27MHz Receiver -  for RC model remote control.   __ Designed by Peter Jakab

Superregenerative Receiver built by GE labs -  Schematic only __ Designed by Peter Jakab

Super-Tiny Receiver -  Here is a VLF receiver built into an earphone plug!  I recently acquired a digital voice recorder to replace the microcassette recorder above and discovered that it is extremely sensitive, easily amplifying the signal from the FET version of the computer-powered receiver above.  This new receiver consists of a very low current JFET, a bias resistor (2, 22 megohms in series) and a capacitor; that's all!  The recorder is designed to power electret microphones so no battery  __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

Supporter for my fiber glass antenna mast -  This is my Homebrewed fiber glass antenna mast supporter used for a 10 meter tall fiber glass antenna mast (made in May 2005)  __ Designed by Bjarke Korsgaard

Surplus 30 to 80 MHz filter -  This is a Radio Astronomy Project __ Designed by Radio-Sky Publishing

SW Receiver using the ZN414 -  A Short Wave Receiver based on the MK484 (formerly ZN414) that includes the tropical bands and 49 metre bands.   __ Designed by Andy Collison

SW Regenerative Receiver -  Sensitivity and selectivity are the major concerns of a short wave enthusiast when he looks up for a receiver.  Commercial communications models with superhet circuitry surely satisfy his requirements, but these are expensive.  He would rather go for a Homebrewed radio, being a regenerative receiver an affordable choice __ Designed by Ramón Vargas Patrón

SW RF Pre-Amplifier -  A radio frequency amplifier to boost SW reception.  Frequency range approximately 5 to 20 MHz.   __ Designed by Andy Collison

SW30+ 30 Meter CW Transceiver -  Summary - This 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

SWR Bridge -  Ham Radio - Other __ Designed by Guy Roels ON6MU

SWR Bridge 1 to 1000 Mhz (1GHz) -  This SWR bridge is not my own invention, OZ3SW and OZ9MO has improved the design after DJ7VY construction in ukw-berichte 1/83.   This is a construction set made for the members of Frederikssunds EDR Club, all I did was a bit of gluing and soldering.  Thanks for all the hardware help, parts help, calibrating and measuring !  you know who I mean ! !  __ Designed by Thomas Scherrer OZ2CPU

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

SWR Direction Coupler 5 to 500 Mhz, made to be used with the Digital Wattmeter -  This Direction coupler can be used from 5 to 500 Mhz.  I have not tested it above 500 Mhz
This design and PCB is not my own invention, but an old project from my local EDR club.  it can be used with the Digital Wattmeter that has a special measurement screen that displays the difference between two signals.  This difference is displayed both in dB and SWR ! !  __ Designed by Thomas Scherrer OZ2CPU

SWR meter for 1 to 1300 MHz -  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

Synchronous Oscillator Converts Audio, Video to FM  -  07/22/99 EDN Design Ideas:  The synchronous oscillator (SO) and the coherent phase-locked synchronous oscillator (CPSO) are universal multifunctional networks that track, synchronize, and amplify as much as 80 dB; improve SNR by as much as 70 dB; and modulate AM, FM, and FSK signals Design by Vasil Uzunoglu, Synchtrack, Gaithersburg, MD

Synthesized ACARS, Aircraft band receiver  -  This low cost, 117-137 MHz Aircraft Band Receiver was designed to receive and decode ACARS data via PC control.  The receiver consists of a tracking input bandpass filter, single conversion mixing stage, Crystal and Ceramic iF filter stages, PLL synthesized LO, RF / iF AGC circuits, data slicing circuit, audio output stage -- all controlled by a PIC  Microcontroller.  The interface to the PC is via a 9600 Baud RS232 link. __ Designed by Steve Hageman

Synthesized HF Receiver -  This receiver was originally designed for simplicity and low cost, but, like other projects, it grew.  My receiver is now synthesized and the performance is quite comparable to many commercial designs.  The unusual features of this design are: * Common AF transistors and AF circuitry have been used for the iF amp, in a transformerless design.  This aids construction and stability.  ; * iF bandwidth is restricted by conventional L.  C.  tuned circuits which are not damped by any resistive or active devices.  This gives a performance, even for CW working.  The iF is 500KHz and NOT 465KHz.  ; * Options for three different Local Oscillators.  I used a Marconi Sig.  Gen.  with this receiver for over a year, before I overcame lethargy and built a decent LO __ Designed by Harry Lythall-SM0VPO

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