10 Transistor-10 IC SW Receiver

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This is a 10 transistor-10 IC Shortwave and communications receiver. It covers broadcast and amateur (ham) bands from 5.7 to 18.2 MHz, and demodulates AM (amplitude modulation) and SSB (single side band) signals. The receiver is a dual conversion superheterodyne system with the following features: an RF (radio frequency) amplifier in the front end for high sensitivity with a short wire antenna, independent RF (preselector) tuning for perfect tracking, balanced mixers with independent VFO (variable frequency oscillator) and crystal oscillator for minimal spurious response, a high first IF (intermediate frequency) of 10.7 MHz for excellent image rejection, 2 mechanical filters for high selectivity in AM and SSB modes, a two-stage IF amplifier with an advanced AGC (automatic gain control) system for high dynamic range, 2 selectable AGC speeds, a roofing IF filter to reduce wideband noise, an active product detector with strong signal handling capabilities, a variable BFO (beat frequency oscillator) for easier SSB resolving and a digital frequency display for easy station location and tuning. The receiver runs on 12 volts DC (direct current) and performs as good as or better than portable shortwave receivers on the market.

By popular demand, I have included a schematic (150K) for this receiver.

Dimensions: 9 3/4 (W) x 4 1/4 (H) x 7 5/8 (D). Controls from left: below: antenna gain, preselector peak, tuning, on/off, BFO (USB/LSB). Above: AM/SSB, volume. Signal meter shows relative signal strength. Digital frequency display simplifies stations location.


Backlit LCD shows tuned frequency in any lighting conditions. Two reduction drives in series give 50:1 tuning ratio for easy tuning.


Additional controls which didn't fit on the front panel were placed on the back. From left: speaker/phones jack, mute, 12 volts supply, IF wide/narrow, AGC fast/slow, filter 5.5K/2.5K, and ground and antenna connectors.


All circuits were built "Manhattan style" with 3/16 pieces of PCB glued on the boards, which simplified experimentation and testing during assembly. BFO and buffer board is on far left. Product detector board is to the right of BFO board.


The peaking capacitor (right) was interfering with the tuning capacitor. A shield between the capacitors corrected the problem. Interference from the digital frequency counter (green board) was kept to a minimum by placing it away from sensitive circuits. Coaxial cables were used to carry RF and AF signals.


Although the main receiver sections were assembled on a single board and not shielded from each other, interstage interference was reduced by keeping leads short and using the whole copper surface as a common ground.


A short history | My radio background | Homemade radios | Tube radios
Transistor radios | World band radios | Kit radios | Reel tape recorders
My other interests | Pictures of Lebanon | Radio links
Home | Showcase | About this site

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