Low-frequency-converter


Posted on Nov 26, 2012

Among the signals below 550 kHz are maritime mobile, distress, radio beacons, aircraft weather, European Longwave-AM broadcast, and point-to-point communications. The low-frequency converter converts the 10 to 500kHz LW range to a 1010 to 1550kHz MW range, by adding 1000kHz to all received signals. Radio calibration is unnecessary because signals are received at the AM-radio`s dial setting, plus 1 MHz; a 100-kHz signal is received at llOO kHz, a 335-kHz signal at 1335 kHz, etc. The low-frequency signals are fed to IC1, a doubly-balanced mixer.


Low-frequency-converter
Click here to download the full size of the above Circuit.

Transistor Q2 and associated circuitry form a Hartley 1000-kHz local oscillator, which is coupled from Q2"s drain, through C8, to IC1 pin 8. Signals in the 10-550 kHz range are converted to 1010-1550 kHz. The mixer heterodynes the incoming low-frequency signal and local-oscillator signal. Transistor Q3 reduces IC1"s high-output impedance to about 100 !l to match most receiver inputs. Capacitor Cl5 couples the 1010-1550 kHz frequencies from Q3"s emitter to output jack ]3, while blocking any de bias. Inductor L6 couples tire de voltage that"s carried in the rf signal cable from the rcvr/dc adaptor. The de voltage and rf signals don"t interfere with one another; that saves running a separate power-supply wire, which simplifies installation at a remote location. Capacitors Cl4 and Cl3 provide de supply filtering. The kit is available from North Country Radio, P.O. Box 53, Wykagyl Station, NY 10804.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

10 Band Audio Equalizer
Water Activated Relay circuit board
digital to analog
inverter circuit diagram
Audio Level Meter
Audio
Simple optical switchs
The Aurora Alarm
Transcutaneous Electrical Nerve Stimulator (TENS)
Kit Car Design & Build
Aikido octal mono PCBs and 5687 PCBs and Aikido and 300B amplifiers
Electric blankets circuit



Top