FEATURES & SPECIFICATION
q 144 to 146 MHz band.
q Excellent performance, less than 1µV sensitivity.
q Tuned input, low noise preamp stage.
q Front Panel Volume, Squelch, and Tuning controls.
q True Dual-conversion super heterodyne design.
q 1 Watt audio output inbuilt speaker.
q 130mm x100cm x40mm, 600gms.
q 9-12V Power Operation
q Available as a DIY kit or fully assembled high quality components for reliable operation.
q Low Cost.
The LRR200 is a commercial-grade vhf fm receiver available in models for various bands, both in kit form, wired and tested. The LRR200 features a front end with low-noise dual gate Mosfet and double tuned circuits for excellent sensitivity and rejection of out-of-band interference. It has a 4-pole ceramic filter for close channel spacing for repeater operation.
INTEGRATED FM RECEIVER
The MC3362 is a complete FM narrowband receiver from antenna input (pin 24) to audio output (pin13). The low voltage dual conversion design results in low power drain, excellent sensitivity and good image rejection in narrowband voice and data link applications. The first mixer amplifies the signal and converts this RF input to 10.7 MHz. This IF signal is applied to the second internal mixer via pin 19, where the 2nd IF frequency of 455 KHz is achieved by mixing with the 10.245 MHz oscillator. The oscillator circuit is internal to U2; the crystal is Y1, 10.245 MHz .The 455 KHz second IF output (pin 7) requires filtering. We used a precision ceramic 455 KHz filter with 4 poles for a 2nd IF filtering scheme designed to solve the adjacent- frequency swamping effect.
The receiver has good "hysteresis" characteristics, the ability to hold the squelch open once it has been broken by a marginal signal, even if the signal becomes weaker. The squelch is activated by signal strength, not by noise.P2 permits squelch adjustment.
RF Input Freq
The Local oscillator tunes the frequency from 133 to 135.600 MHz to cover the input frequency of 143.700 to 146.300 MHz with a bandwidth of 2.6 MHz.
For example if you need to tune 145.150 MHz you have to turn the tuning knob clockwise direction from the start to 5 turns plus ½ turns.