Thursday, 3 March 2011

Wayne Burdicks modified Neophyte receiver for shortwave reception



The modification described here provides coverage of 6O·meter tropical broadcasting (4750-4995 and 5005-5060 kHz), the standard-frequency-and-time allocation at 4995-5005 kHz, 49-meter international broadcasting (5950-6200 kHz) and frequencies used by the aeronautical mobile, maritime mobile and fixed services between 4520 and 6250 kHz.

Wayne Burdick put his Neophyte receiver on 15 m and modified its audio response for better CW reception as shown here. The parts associated with U1's pins 6 and 7 serve as frequency-determining and feedback elements in U1's local-oscillator subcircuit; C1,C2, RFC1 and RFC2 reduce the receiver's audio response above 1 kHz; and R1 and C3 reduce hiss by decreasing U2's response at higher audio frequencies.

T1's secondary winding consists of 26 turns of #24 enameled wire on a T~50-6 toroidal core; the primary is 2 turns of #24 enameled wire over the secondary'S pin 2 end. l1 consists of 26 turns of #24 wire on a T-SO-6 toroidal powdered-iron core; RFC1 and RFC2 are Mouser Electronics 43LJ4l0 chokes. All electrolytic capacitors are 16 V.

See Fig and Table,. C21, a 220-pF capacitor, and S2, an SPST toggle switch are new components. S2, BAND, switches C21 in parallel with the original Neophyte's ClO to select added "low-band" option.

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