10/01/09: After 15 years of service, the old Solderless BreadBoard has been replaced. The new board is a Radio Shack 276-001: essentially the same as the old. The Aluminum Back-plate is not as thick, and is not cast. Nonetheless, there are essentially no performnce differences. One "just in case" mod was made to run a jumper-wire directly to ground plate from the return side of the coils. This DID make a small but noticible hearing/loudness improvement (4-6 db) on both new and old boards. This connection is marked J2 (jumper) in the updated wiring diagram and is shown terminating to a ground plane screw.

A simple radio is presented for your enjoyment of the AM radio band. If you've seen or built a CK722 model radio, the Am3 Radio is directly descended from that 1st generation hobbyist receiver. The tuning section is both detected and directly amplfied by the one transistor circuit. The Am3 Radio has very good reception using newer technology: the transistor signal gain of the MPSA18 Silicon transistor is 700+, the capacitors are of very high Q (about 2000) and designed for the purpose used, and the cake-frosting cans have very low loss. Some things are the same, the resistors, wire, the crystal earphones, and the ceramic trimmer.

The Am3 Radio illustrates the progress made to the simple design of the CK722 radios some 55 years ago. Volume is adequate for the listener for the most part. The Am3 Radio takes very little power from a pair of AA cells only 100uA at 3 Volts. No soldering iron is needed if using a "Solderless Breadboard" to assemble the circuit. There is no need for an external antenna: the set works quite well using just the telephone ground. I hope you enjoy building and listening to the Am3 Radio.

The Am3 Radio Revision H3 using a high-gain transistor as the detector and amplifier.

Tweaks and Updates: Tuning Chart and Parts List

Here's a link to a PDF file of AM-3 Station Contacts .

This PDF file is the log for the Kaito WRX911, Tecsun PL-200, & Tecsun PL-310 DSP Ultra-Light spotter radios.

This PDF file describes the Am3 Score Formula that accounts the subjective 'High Quality DX' of the receiver, location, and conditions.

FCC results of the 2006, 2007 DXRX Contests and October 2007 iBOC Scan

,