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paulsherwin · 26th May 2004, 6:14 pm

Sorry Ed, this thread has rambled a bit. The coils are standard MW and LW coils from an ancient scrap trannie. These particular coils have a tap about 90% along the winding, but you could use coils with a separate low impedence winding easily enough. Only one coil is shown in the circuit diagram - the wavechange switch switches the connections to the transistor base and the variable cap.

The only drawback with using scrap trannie coils is that it's sometimes difficult to work out which connection is which. I got the MW connections wrong at the first attempt.

There are probably better designs around than this - I basically made it up as I went along, and have stuck with it because it works.

Best regards, Paul

26th May 2004, 6:14 pm	#14
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,934	Re: Building an external ferrite rod aerial Sorry Ed, this thread has rambled a bit. The coils are standard MW and LW coils from an ancient scrap trannie. These particular coils have a tap about 90% along the winding, but you could use coils with a separate low impedence winding easily enough. Only one coil is shown in the circuit diagram - the wavechange switch switches the connections to the transistor base and the variable cap. The only drawback with using scrap trannie coils is that it's sometimes difficult to work out which connection is which. I got the MW connections wrong at the first attempt. There are probably better designs around than this - I basically made it up as I went along, and have stuck with it because it works. Best regards, Paul