One Watt 2.45 GHz Linear Amplifier - Schematic: Reversed PCB pattern: BOM: Schematic Reference Value Package Capacitors C1 1 µF electrolytic, 10%, 16V SMT or leaded C2, C3 1000 pF ceramic, X7R, 50V 0603 SMT C4 22 pF Johanson ceramic 5%, 100V 0504 SMT C5 3.3 pF __ Designed by www.gbppr.org
One Watt Audio Amplifier Project (Using the TAA300) - I built this audio amplifier with the TAA 300 Integrated Circuit (IC) to have on the work bench an independent amplifier to test audio signals coming from radio receivers or audio oscillators. It is an excellent amplifier to drive an eight ohm loudspeaker. You can use it, for example, as an audio amplifier for the FM one transistor receiver known as the Radio Shack Special and/or the TDA 7000 FM receiver; also to test the workings of a pulse oscillator or any other kind of audio oscillators. __ Designed by braincambre500 @ yahoo.com
One-Transistor Amplifier/Detector - An amplifier may be added to boost the audio level as shown below. The current consumption of this amplifier is quite low and a power switch is not included. Disconnect the battery when the receiver is stored for long periods. __ Contact: Charles Wenzel of Wenzel Associates, Inc.
Op Amp Radio - Here is a simple radio that is easy to build and inexpensive. In fact, you probobly have all the parts you need in your junk box. You'll be suprised at the great reception with this little set. __ Designed by Aaron Cake
Opamp Basics - The op-amp is basically a differential amplifier having a large voltage gain, very high input impedance and low output impedance. The op-amp has a "inverting" or (-) input and "noninverting" or (+) input and a single output. The op-amp is usually powered by a dual polarity power supply in the range of +/- 5 volts to +/- 15 volts. A simple dual polarity power __ Designed by Bill Bowden
Operating precautions for RF Amplifiers - AN-60-008 App Note__ MiniCircuits.com
Original One Transistor FM Radio - Schematic Only __ Designed by Andrew R. Mitz
Other Repeater Controller Construction Projects - The links below will allow you to build several working repeater controllers. No warranty as to the quality or usefulness is expressed by Repeater Builder.
Phase Noise in Signal Generators - Phase noise serves as an important oscillator parameter and some amateur radio enthusiasts seem confused about what it is, how it’s measured, and most importantly, how it might affect what they’re working on __ Contact: Vasily Ivanenko
Photo Tour of a Bird Wattmeter Element - Ever wonder what's inside one of those elements? __ Designed by Robert W. Meister WA1MIK
PL-CG (CTCSS) Filter Construction Projects - Build several PL (CTCSS) Filters!
Pocket sized 20m (30m) CW QRP transceiver - I started to discover the 30m band by using an adapted version of my 80m single-board CW transceiver. The first impressions were quite encouraging, so I decided to build a portable transceiver for this interesting band. There was no dilemma about the modulation the transceiver has to support, since the SSB is on 30m not allowed. I also decided not just to adapt an earlier design, but to design a completely new transceiver. 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 __ Designed by Aleksander Stare
POCSAG Paging Network How-To - Homebrew your own amateur radio text or tone paging system. __ Amateur Radio circuits from Green Bay Professional Packet Radio
Pre-and De-Emphasis component values - Pre-calculated common component values. __ Designed by W9ZGS.
Precision 20 MHz reference 'clean up' PLL (Xtal oscillator locked to an external reference) - In many test systems a master 10 MHz reference is 'piped' around to all the measuring instruments and sources. Many instruments do not use an internal 10 MHz clock, instead some convenient frequency specific to the particular instrument is used. Even if the instrument uses 10 MHz internally the external input is commonly 'cleaned up' with the use of a narrow band PLL, this helps __ Designed by Steve Hageman
Precision Frequency Control for AM Radios-A Frequency Synthesized Local Oscillator - Chasing DX late at night on the AM radio band can be a lot of fun but if you get serious enough about it to start logging station calls and times you will also want to log the frequency. The dial calibration on AA5s is not even close enough to be sure what 100 kc segment you are in. Even those early high fidelity AM tuners didn't have Collins-like calibration. If you are lucky enough to have an R-390 or something similar, fine. If you aren't so endowed, read on. __ Designed by Max Robinson
Precision measuring receiver (Selective Level Meter) - This receiver was designed to precisely measure communication channel power over a 90 dB or greater range. This is useful for monitoring and installation of radio communication systems. The basic design can be adapted to the low VHF region through 6 GHz. A TCXO and PLL synthesizer assure accurate frequency setting, while a precision Logarithmic Amplifier (Log Amp) detection scheme __ Designed by Steve Hageman
Precision Portable Voltage Reference - It has been said that a man with one watch knows what time it is, but a man with two watches is never sure. The same can be said for a person who has more than one voltmeter. In my situation, I have several voltmeters in each of two different locations a third of the way around the world apart. The best solution would be to send the meters to NIST traceable calibration labs, __ Designed by Dick Cappels
Protects Phone Line from Lightning Strikes - 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
PTT Delay Circuit - The delay circuit is inserted between the controller and transmitter to provide a set-able time delay keeping the transmitter keyed when using "zero hang time" and linking to another machine. To use this circuit, the controller's repeater ptt must be configured "high true" (dip switch 2 on) . __ Designed by Kevin Custer W3KKC
QRP Antenna Tuner - This circuit is for a QRP (low power) antenna tuner, a. k. a. a transmatch, for use in the short wave amateur radio bands from 3-30 Mhz. It allows a wide variety of antennas to be connected to a low power transmitter. When the circuit is properly tuned, the maximum transmitter power will be delivered to the antenna. It is used in conjunction with a standing wave ratio (SWR) meter. This is a fairly generic antenna tuner circuit. __ Designed by G. Forrest Cook
QRP Keyer - This is not a sophisticated automatic keyer but it is lot QRP to build and to have fun operating it. When the paddle is connected to the DOT terminal, C1 starts to charge. When C1's charge reaches sufficiently high value, it causes the transistor BC157B to conduct and pulls the relay and key the transmitter. __ Designed by K P S Kang
Qualcomm OmniTRACS Experiments - Using Qualcomm OmniTRACS fleet tracking satellite systems for amateur radio applications. __ Amateur Radio circuits from Green Bay Professional Packet Radio