Loop Antenna For 3.5 Mhz
C1 = 3 750 pF 500 V silver-mica capacitor. C2= 100 pF preset capacitor (Jackson C803). C3 = 75 pF variable capacit...
Wideband Active Rod Antenna
A J309 Siliconix FET feeds a 2N5109 in a wideband RF amplifier configuration. A relay is used to bypass the amp...
Active Antenna Ii
This circuit provides 14- to 20-dB gain at frequencies from 10 kHz to 30 MHz. The antenna length can be anything between ...
Active Antenna I
This circuit is designed to make a short pull-up antenna perform like a long wire antenna, while offering no voltage gain....
Active Antenna With Gain
The signal booster, built around a few transistors and support components, offers an RF gain of about 12 to 18 dB ...
Ultrasonic-receiver
The piezo speaker, MICl, picks up the incoming ultrasonic signal and feeds it to the base of Ql. The two-transistor booster amplifier, Ql and Q2, raises the si...
Wireless-fm-microphone
Use standard rf wiring precautions. The best speech clarity is obtained by using an electret microphone. ...
Qrp-cw-transceiver
This is a 3-W, single-circuit board, VFO-controlled CW transceiver for 40 or 30 meters, featuring a direct-conversion receiver with audio filtering, Receiver I...
Fm-multiplex-transmitter
This transmitter has a range of up to 100 feet. It generates a complete multiplex stereo signal and is useful for cordless headphone applications in which an i...
A-one-transistor-fm-transmitter
The 2N2222 circuitry is a three-element, phase-shift oscillator circuit, designed to yield a 1,000-Hz sine wave. The 1,000-Hz sine wave is then applied to the ...
902Mhz-cw-transmitter
The oscillator, Q1, is a standard overtone circuit. A fifth-overtone crystal, 80.545 MHz, is operated on the seventh overtone, 112.763 MHz. C6 couples the outp...
Wireless-fm-microphone
Adjustable capacitor C10, and coil L1 form a tank circuit that, in combination with Q1, C2, and R1, oscillates at a frequency on the FM band. The center freque...
Vhf-modulator
This circuit uses an oscillator (2N2222) and a diode Dl as a nonlinear mixer. The frequency is set by a slug in Ll. ...
40M-cw-transceiver
The unit consists of a direct conversion receiver and 1-W transmitter. The direct conversion receiver VFO is tuned just off frequency from the incoming signal. ...
Beacon-transmitter
This transmitter can be used for transmitter hunts, for remote key finding, or for radio telemetry in model rockets. It can be tuned to the two meter band or o...
Wireless-fm-microphone
Transistor Q1 acts as an amplifier for condenser microphone MIC1. The output of Q1 is applied to the base of transistor Q2 through a 4. 7 -I"F capacitor. C2 an...
Low-frequency-transmitter
The crystal oscillator, which uses two sections of IC1, a 4001 quad 2-input NOR gate, is a standard and reliable design. The oscillator"s 1.85-MHz, square-wave...
Vhf-tone-transmitter
The range of this transmitter is about 50 feet with a short whip antenna. The tone generator, is made up of a unijunction transistor, Q1, and R1, R2, R3, and C...
Fm-snooper
The FM Snooper is an FM transmitter that radiates a continuous wave whose frequency is altered according to the sound waves striking the microphone. An ordinar...
1W-cwtransmitter
This is a little transmitter that could be put into a plastic Easter egg. It delivers approximately 1 W of measured rf output into a 50-0 dummy load, and creat...