MK484 Kit 4 includes:
- 1 – Ceramic Earphone (Piezoelectric Earphone , Crystal Earphone)
- 1 – MK484 IC
- 1 – 100K Resistor
- 1 – 1K Resistor
- 1 – .1uf Capacitor
- 1 – .01uf Capacitor
- 1 – 680uh Loopstick Antenna Coil with tap at 470uh
- 1 – Plastic Variable Capacitor 60pf /141pf
- 1 – AA Battery Holder
MK484 Kit Number 4 has a 680uh coil with a tap at 470uh.
The MK484 Kits are TRF ( Tuned Radio Frequency, Tuned RF ) type receivers. This the most basic type of radio receiver with no regeneration or re-genitive feedback. The variable capacitor and antenna coil form a “Tank” circuit that tunes the radio stations frequency then the MK484 amplifies the radio stations radio frequency then “Rectifies” (Converts to Audio) it then amplifies the audio and powers the Earphone.
Yes a real MK484, not like other sites that sell MK484/TA7642. If you see this designation on other sites you are getting a TA7642 not a MK484.
The alternate circuit diagram for the MK484-Kit-4 will have greater selectivity with a little less volume. For an antenna, if you want to try one, just wrap about 5 turns of small gauge wire around the ground side of the ferrite rod and connect one end of the 5 turn coil to an antenna and the other to a ground. A common ground to circuit is not needed. The MK484 over loads very easy so a long antenna might over load it and station separation will suffer. Keep the same audio output circuit for the headphone or earpiece type you are using. The changes are for only the tunning input section.