Carpet Loop Antenna part 3
Carpet Loop Antenna part 3: Tuner Construction
With the exception of C1, all parts for the tuner are readily available from Radio Shack. C1, the 365 pf variable capacitor, can be gotten out of an old radio.
There are no critical parts in the tuner; as long as S1 has at least six positions, it will do. D1 and D2 can be any silicon diode. Use any enclosure that’s big enough to comfortably install components in.
The choice for J3, the jack to the receiver, depends on what connector your radio uses for an external antenna. I used an SO-239 (RS #278-201); you could also use a TV antenna terminal strip (RS#274-663).
Mount the components on the enclosure you’ll be using–all wiring is point to point. I suggest mounting J1 and J2 on opposite sides, S1 and C1 on top, and J3 on the other end of the enclosure.
Wire S1 to J1 and J2. If you use the Radio Shack DP6T rotary switch, you’ll be using just one of the poles. The diagram of the switch is below: D C S1 DP6T rotary E o o B switch G o o A | o o | Viewing from P |o o| bottom of switch | o o | o o o o
Wire as follows:
(Note: If you’re using the Radio Shack terminal strip, you will need to drill a hole in the cabinet to pass the wires through from inside. Use a rubber grommet to keep the wires from chafing and fraying)
S1 Term. –to–> J1 term. J1 term. –to–> J2 term. A #1 #2 #6 B #2 #3 #7 C #3 #4 #8 D #4 #5 #9 E #5
Connect a wire from J2 terminal #10 to the G terminal on S1, and this step is done.
Install and wire C1. Connect one terminal of C1 to the P terminal on S1. Connect the other end to J3. If using the SO239 or phono jack, connect to the center conductor. If using screw terminals, connect to terminal #1 on J3. Skip ahead to step 5.
Connect the P terminal of S1 to J3. If you’re using the SO239 or phono jack, connect to the center conductor. If you’re using screw terminals, connect to terminal #1 on J3.
Connect the G terminal on S1 to J3. Connect it to the ground shield if it’s an SO239 or phono jack, or to terminal #2 if it’s screw terminals.
Connect D1 and D2 across J3’s terminals; remember that D2 is connected opposite of D1.
That completes construction of the tuner.