AM RADIO

INSTRUCTION SHEET

Price - Stock No 170

MK 484

BC 548

1. Make  a  visual check of the P.C.Board to ensure no damage has happened in transit.  Continuity of the tracks can be  checked  with  a  multimeter  or an electronic Circuit Tester.  Any breaks can be bridged with solder.
2. Identify the resistors either by their colour bands, or with a multimeter see Resistors.  Bend the legs to match their holes and assemble them.   
3. Solder in place - see Soldering Technique.    
4. There are two 0.1uF and one 0.01uF capacitors see Capacitors.  Mount the capacitors in their correct positions and solder in place.
5. Insert the 47 uF capacitor - be sure to observe the corect polarity.
6. Nine pins are in the kit.  These are soldered into the four AM Coil connection points, one antenna point, two for the battery points and two for the jack socket. 
7. Insert the tuning capacitor and solder.
8. The  BC 548 and the MK 484 must be insert in the correct orientation.  The component and PCB diagrams above will assist.  Caution should be exercised when soldering these components.  Excess heat may damage these components however, sufficient heat from your soldering iron should be applied to make sound connections.
9. Solder the jack socket to it's PCB pins.
10. Connect the battery holder - Black to 0 V, Red to + 1.5 V.
11. Take the hook up wire and tin one end - refer Tinning wire.  Connect the antenna to its PCB pin.
12. Connect the four leads of the AM Coil.  These are colour coded and caution should be taken to identify and correctly connect them.
13. Your AM radio is now complete and ready for a battery, an earpeace and testing.

Circuit description and tuning notes

The heart of this circuit is the MK 484.  It is a purpose built AM radio.  The radio station is tuned with the variable capacitor, which in conjunction with the inductor isolates a frequency on the AM radio spectrum.  The information (talking / music) on this frequency is delivered to the MK 484 at it's input - leg 2.  The output, which is quite low level is then coupled (via a capacitor) to the base of the BC 548.  The BC 548 amplifies the information to a level that can be heard through an earpiece.

TROUBLESHOOTING

If the AM Radio doesn't work check the following:

• The BC 548 ank MK 484 are inserted correctly.  
• The five resistor values are as the diagram shows.
• The 47uF capacitor is in the correct orientation. 
• The inductor and battery wires are connected correctly.  
• Check  all  soldering.  Re-solder  any joints that look suspicious, making sure that the solder takes to the track as well as to the legs.
• The battery is not flat.

Contact CdS electronics

Home Page