SIMPLE REGENERATIVE RECEIVER

80 and 40 with one FET and a low component count

COMPONENTS LISTRESISTORS All 1/8 W carbon1k0, 2k7, 1M010k Linear potentiometer

CAPACITORS15p ceramic*, 4p7 ceramic*, 150p ceramic, 50p polystyrene, 100p silver mica or polystyrene, 300p polystyrene, 0µ1 polyester film, 2 X 33µ 16v electrolyticVariable capacitor 208 + 176pF (176p section only used)* C1a and C1b - selected for optimum selectivity performance: actual values may differ from guide values shown.

SEMICONDUCTORSN-channel FET J310 or 2N4416 preferred 2N3819 will do (select on test)

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: 10:1•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.)

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 (< 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

CIRCUIT DIAGRAM

d

s

g

COIL CONSTRUCTION

(insulated hook-up wire)

RECEIVER LAYOUT DIAGRAM (SUGGESTED)

KNOW YOUR FET!

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...

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.

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..

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...

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 (< 10mm.).

9. Solder one end of R1 / C2 to the VC rear section fixed plates terminal (RHS). more...

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...

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...

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…

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..

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.

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...

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...

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...

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!