UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Jonell Radio. A cheaper version of the Ace 50.

G6Tanuki · 13th Jun 2018, 7:56 pm

I wonder if your tuning-coils could be similar to the Barker-88: basically on MW/LW the aerial is fed [through the primary of a SW coil - L1] to a capacitor (C2) between the bottom-end of the MW/LW coil and earth. It works as a sort-of- "Pi-network" with a fixed input capacitor (C2) and a variable output-capacitor to tune it.

On shortwave it's more traditional.

This only works because the inductance of the SW-coil's primary winding is (L1) very low at MW/LW frequencies, and conversely the fixed-capacitor in the MW/LW circuit (C2) has a low impedance on short waves.

13th Jun 2018, 7:56 pm	#37
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,998	Re: Jonell Radio. A cheaper version of the Ace 50. I wonder if your tuning-coils could be similar to the Barker-88: basically on MW/LW the aerial is fed [through the primary of a SW coil - L1] to a capacitor (C2) between the bottom-end of the MW/LW coil and earth. It works as a sort-of- "Pi-network" with a fixed input capacitor (C2) and a variable output-capacitor to tune it. On shortwave it's more traditional. This only works because the inductance of the SW-coil's primary winding is (L1) very low at MW/LW frequencies, and conversely the fixed-capacitor in the MW/LW circuit (C2) has a low impedance on short waves. Attached Thumbnails