Rf-modulator
Two IC rf modulators convert a suitable baseband video and audio signal up to a low VHF modulated carrier-Channel2 through 6 in the U.S., and 1 through 3 in ja...
Simple-low-cost-rf-switch
When the digital logic level at the control input is low, the PIN diode is forward-biased by the CMOS gates. The two 1-KO bias resistors limit this current to ...
Bug-tracer
The bug tracer is made up of a simple rf-injector circuit consisting of Ql and Q2, and a pocketsize, AM broadcast receiver. The two-transistor rf-injector circu...
Qrp-swr-bridge
The design shown is a simple unit for QRP operation on all authorized frequencies up to 30 MHz. based on a toroidal transformer Tl. The secondary winding of Tl...
Lc-checker
The circuit is based on the grid-dip or absorption effect, which occurs when a parallel resonant circuit is coupled to an oscillator of tbe same frequency. Q...
Personal-pocket-pager
When activated, the transmitter sends out a 49.890-MHz, AM rf carrier. The.receiver detects, amplifies, and decodes the rf signal, which, in turn, activates a ...
On-the-air-indicator
The circuit is a simple rf-actuated switch which will respond to any strong field in the region of the pickup wire. The length of the wire will depend on how m...
Rf-actuated-relay
Automatic antenna switching or rf power indication can be achieved with this circuit. ...
Broadcast-band-rf-amplifier
The circuit has a frequency response ranging from 100Hz to 3 MHz; gain is about 30 dB. Field-effect transistor Q1 is configured in the common-source self-biase...
Wideband-uhf-amplifier
The amplifier circuit is designed for a 225 MHz center frequency, 1 dB bandwidth of 50 MHz, lowinput VSWR in a 75-0 system, and 24 dB gain. ...
Field-strength-meter
The untuned, but amplified FSM can almost sense that mythical flea"s whisper-from 3 through 148 MHz no less-and yet, is so immune to overload that the meter ...
565Sca-demodulator
This application involves demodulation of a frequency-modulated subcarrier of the main channel. This popular example uses the PLL to recover the SCA (Subsidiar...
Shortwave-converter
The NE602, U1, contains oscillator and mixer stages. The mixer combines the oscillator signal with the input rf signal to produce signals whose frequencies are...
4-18Mhz-converter
The unit consists of rlamplifier Q1, local oscillatorQ2, and mixer Q3. The two bands are covered without a bandswitch by using an i-f or 3.5 MHz. The oscillato...
Low-frequency-converter
Among the signals below 550 kHz are maritime mobile, distress, radio beacons, aircraft weather, European Longwave-AM broadcast, and point-to-point communicatio...
Carrier-current-am-receiver
The AM Tuned Radio Frequency (TRF) receiver, has a sensitivity of about 1 m V at tbe input for an audio output of "iz W. Capacitor C22 couples audio signals fr...
Carrier-current-fm-receiver
Input signals from the power line are coupled through C23 and R19 to the input filter network. C23 must be rated at 600 volts. Switch 52 is used as an attenuat...
Carrier-current-audio-transmitter
The decision to use either AM, narrowband FM Oess than 15kHz), or wideband FM (greater than 30 kHz) depends on the application. For the transmission of music, ...
Portable-rf-burst-generator
The circuit generates low-level rf bursts having frequencies as high as 10 MHz, thus permitting field testing of high frequency receivers. A jumper-selectable ...
Active-antenna
All capacitors in this circuit are disc ceramic. Fixed-value resistors are 1/.-or 1/2-W carbon. Rl controls the gain of Ul. RFCl is a miniature 2.5mH rf chok...