Simple%20Regenerative%20Receiver

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SIMPLE REGENERATIVE RECEIVER
80 and 40 with one FET and a low component count
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COMPONENTS LIST RESISTORS All 1/8 W
carbon 1k0, 2k7, 1M0 10k Linear
potentiometer CAPACITORS 15p ceramic, 4p7
ceramic, 150p ceramic, 50p polystyrene, 100p
silver mica or polystyrene, 300p polystyrene, 0µ1
polyester film, 2 X 33µ 16v electrolytic Variable
capacitor 208 176pF (176p section only used)
C1a and C1b - selected for optimum selectivity
performance actual values may differ from guide
values shown. SEMICONDUCTORS N-channel FET
J310 or 2N4416 preferred
2N3819 will do (select on test)
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• COMPONENTS LIST (continued)
• MISCELLANEOUS
• 4mm. sockets - 3 off (2 red, 1 black) - or piece
  4-way choc block
• Min (3.5mm.) jack socket
• Min switch, SPST
• Slow motion drive for tuning capacitor 101
• Knobs for VC and VR
• 3 X 4BA short machine screws (or 4BA studding
  nuts) washers / spacers (VC mounting) 1 X
  4BA m/c screw nut large washer (coil
  mounting)
• Plastic 35mm. Film can (coil former)
• 22g (/-) insulated hook-up wire for coil (2M
  approx.)

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• COMPONENTS (continued)
• MISCELLANEOUS (continued)
• Printed circuit board, drilled for VC and L1,
  150mm. X 100mm. X 1mm. thick (approx.
  measurements)
• Shaped 4BA screw(s) and nut(s) - tuning drive
  retainer.
• Hook-up wire (lt 100mm.)
• 9v battery (PP3 or equivalent)
• PP3 type battery clip and lead
• Double-sided sticky tape (100mm X 15mm approx.) -
  to secure coil turns
• Rubber feet

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CIRCUIT DIAGRAM
d
g
s
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COIL CONSTRUCTION
(insulated hook-up wire)
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RECEIVER LAYOUT DIAGRAM (SUGGESTED)
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KNOW YOUR FET!
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BEFORE YOU START! 1. Read through the
instructions, referring to the circuit, layout
and constructional diagrams. If there's anything
that doesn't make sense, please ask. 2. When
you start construction, keep the diagrams handy
and check each stage as you go. 3. Tin all
leads before you solder them - but watch out
for the polystyrene capacitors they melt
easily. Use a heatsink if in doubt. more..
.
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BEFORE YOU START! (continued) 4. When placing
major components on the board leave plenty of
room to get in and modify the circuit if
necessary. 5. Keep the construction as rigid as
possible - the final receiver will be more
stable that way. ?
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INSTRUCTIONS 1. Wind the coil first, making sure
that the coils are secure. Use double-sided tape
to secure windings to the former - see the
diagram. Anchor the winding ends by passing
the wire through two holes pierced in the
former. 2. Mount the tuning capacitor on its
back, using 4BA machine screws and spacers. Make
sure that the screws do not foul the capacitor
plates (use washers / spacers under the screw
heads to adjust). Don't fit the reduction drive
at this stage. more..
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INSTRUCTIONS (2) 3. Mount the coil base (film can
cap) to the base-board using a 4BA machine
screw with a large washer and nut. 4. Mount
Aerial and Earth Sockets to the board with
hot-melt glue. 5. Solder a short length of wire
(ca. 50mm. or so) to one switch way terminal
solder one lead of the 150pF capacitor to the
pole terminal. Keep the leads
short. more...
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INSTRUCTIONS (3) 6. Using hot-melt glue, mount
the switch on top of the insulated body of the
earth terminal, making sure that the free lead
of the capacitor can be soldered to ground.
Solder it. 7. Solder the free end of the
switch wire to the VC rear section fixed plates
terminal (LHS). 8. Solder R1 and C2 in
parallel. Keep the leads short (lt 10mm.). 9.
Solder one end of R1 / C2 to the VC rear
section fixed plates terminal (RHS). more...
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INSTRUCTIONS (4) 10. Solder C3 and C4 together in
series (short leads) solder the free lead of C3
to the free end of R1 / C2. 11. Solder the
free end of C4 to ground (short lead). 12.
Using hot melt glue, secure the regeneration
potentiometer (VR) in position - make sure it's
at least 10mm. from the front edge of the
board. 13. Solder to ground the rightmost of the
three VR terminals. more...
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INSTRUCTIONS (5) 14. Solder C6 (-ve) and R3 to
the VR centre terminal. Solder the free lead
(-ve) of C6 to ground. 15. Solder C7 (ve) to
the remaining (leftmost) VR terminal. Solder C7
free lead (-ve) to ground. 16. Solder C5 to the
junction of C3 / C4 / R2. It'll probably help
rigidity if this component is stuck down to the
board with hot melt glue. 17. Position the
output socket on the right hand edge of the
board. Secure in position with hot melt
glue. more...
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INSTRUCTIONS (6) 18. Solder the free lead of C5
to the socket tip terminal. Solder the socket's
other terminal to ground. 19. Solder the
battery clip red lead to the junction of VR
with C7. Solder the black lead to ground. 20.
Solder C1a and C1b to Aerial terminals A1 and A2
respectively. 21. Solder the free ends of C1a
and C1b together, and connect (solder) to VC
rear section fixed plates terminal. more
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INSTRUCTIONS (7) 22. Position the coil on its
base. Solder the lower end of the winding to
ground. 23. Solder the upper end of the coil
winding to the VC rear section fixed plate
terminal. 24. Solder the FET in place ! (check
the leadout diagram for your device) ! gate to
junction of C2 / R1 and C3 source to junction
of C3, C4, R2, C5 drain to free lead of
R3. 25. Secure the battery in position. Do not
connect the battery clip at this
stage. more..
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INSTRUCTIONS (8) 26. Check your wiring, paying
special attention to electrolytic polarities and
FET connections. 27. Fit the reduction drive
to VC. Tighten the grub screws. 28.Secure the
drive fixing lugs to the capacitor using 4BA
studding and lock nuts. !Make sure the stud ends
don't foul the capacitor plates! Solder the
lugs to the studs. 29. Fit knobs to VC drive
and VR. ?
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TESTING AND OPERATION 1. Connect an audio lead
between the receiver output jack and audio
amplifier. 2. Connect an aerial, preferably at
least 10M long, to the aerial terminal. 3.
Connect an earth lead to the earth terminal.
Connect the lead free end to a suitable
earth. 4. Switch on the amplifier and turn up
the volume control connect the receiver
battery clip to the battery. more...
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TESTING OPERATION (2) 5. Advance the
regeneration control from the fully
anticlockwise position a point should be
reached where either stations are heard, or a
rushing sound. 6. If broadcast stations are
heard, tune a station and continue to advance
the regen. pot. until volume is maximum,
without the set starting to howl this is the
point of maximum sensitivity and
selectivity. more...
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TESTING OPERATION (3) 7. As the set is tuned
across the band, small adjustments to VR will
maintain the maximum selectivity / sensitivity
point, and further broadcast stations will be
heard. 8. Without C8 switched in, the receiver
should tune 4.5 MHz to 8.5 MHz approximately
with C8 in circuit the range was 3.4 MHz to 4.6
MHz in the prototype. more...
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TESTING OPERATION (4) 9. To receive s.s.b.
transmissions, advance the regen. pot. until the
set just oscillates (rushing sound), tune for a
station and adjust tuning / regeneration for
best intelligible speech. 10. Each time you
re-tune, you'll have to make adjustments to the
regen. pot.. It takes practice, but the rewards
are well worthwhile. Good
Listening!