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Wide band differential multiplexer – Circuit Schematic
Wide band differential multiplexer
This design allows high frequency signal handling and high toggle rates simultaneously...
Receiver for 50Khz FM optical transmitter – Circuit Schematic
Receiver for 50Khz FM optical transmitter
This circuit consists of a L14G2 detector, two stages of gain, and a FM demodulator...
Zero center indicator for FM receivers – Circuit Schematic
Zero center indicator for FM receivers
To adjust, tune in a station and adjust the I"M pot for a null. Then ask the station to modulate and fine adjust so modulation peaks don"t light the LEDs...
Broadband frequency doubler – Circuit Schematic
Broadband frequency doubler
This circuit will double low-level signals with low distortion. The value of C should be chosen for low reactance at the operating frequency. Signal level at th...
4.5Mhz notch filter – Circuit Schematic
4.5Mhz notch filter
Component value sensitivityis extremely critical, as are temperature coefficients and matching of the components. Best performance is attained when perfectly ma...
Simple field strength meter – Circuit Schematic
Simple field strength meter
The circuit is frequency selective. It has been used from 2 meters through 160 meters. The telescoping antenna may be adjusted to its shortest length when worki...
Field strength meter 1-150Mhz – Circuit Schematic
Field strength meter 1-150Mhz
The tuning range is determined by coil (L) dimensions and setting of Cl. Coils can be plugged in for multirange use or soldered in place if only limited frequen...
Adjustable-sensitivity field-strength indicator – Circuit Schematic
Adjustable-sensitivity field-strength indicator
The LED lights if the rf field is higher than the pre-set field strength level. Diodes should be germanium...
Sensitive field-strength meter – Circuit Schematic
Sensitive field-strength meter
Increased sensitivity gives field strength reading from low power transmitters. Operating range 3-30 MHz...
Product detector – Circuit Schematic
Product detector
The MC1596/MC1496 makes an excellent SSB product detector. This product detector has a sensitivity of 3 microvolts and a dynamic range of 90 dB when operating a...
100Khz crystal calibrator – Circuit Schematic
100Khz crystal calibrator
This circuit is often used by amateur radio operations, shortwave listeners, and other operators of shortwave receivers to calibrate the dial pointer. The oscil...
Carrier current receiver – Circuit Schematic
Carrier current receiver
60 kHz transformer consists of a 18 x 11mm ungapped pot core (Siemens, Fer-rocube, etc), utilizing magnetics incorporated type "F" material wound with SOV2 turn...
Variable attenuator – Circuit Schematic
Variable attenuator
The PN4391 provides a low Rds(on) (less than 30 ohms)...
RF-powered sidetone oscillator – Circuit Schematic
RF-powered sidetone oscillator
A sidetone oscillator is a special audio astable multivibrator. Keying is accomplished oscillator that is turned on and off with the by applying a positive dc p...
Remote rf current readout – Circuit Schematic
Remote rf current readout
A suitable pilot larnp is illuminated by a small sample of rf and energizes an inexpensive solar cell; the dc current generated by the cell is a measure of rela...
Self-powered cw monitor – Circuit Schematic
Self-powered cw monitor
Position L near the transmitter output tank to hear the key-down tone. Then tape the coil in place. C = 47 µf, R = 8 K, Q = HEP 253 (or equal), T = 500: 500 ...
Two-meter preamplifier – Circuit Schematic
Two-meter preamplifier
This simple, inexpensive, wideband rf amplifier provides 14 dB gain on two meters...
Rf power meter – Circuit Schematic
Rf power meter
Reflectometer (SWR Power Meter) covers three decades—from 100 kHz to 100 MHz...
RF isolation amplifier – Circuit Schematic
RF isolation amplifier
This wideband RF isolation amplifier has a frequency response of 0.5 to 400 MHz ± 0.5 dB. This two stage amplifier can be used in applications requiring high...
Broadcast band RF amplifier – Circuit Schematic
Broadcast band RF amplifier
The circuit has a frequency response ranging from 100 Hz to 3 MHz; gain is about 30 dB. Field-effect transistor Ql is configured in the common-source self-biase...