I have a portable radio that uses the headphone cord as the antenna. The radio's reception is very sensitive to movement of the headphone cord. I want to build a plug-in device so that a telescopic antenna will replace the antenna function of the headphone cord. The headphone will connect to the radio through this external device. Not being an RF person I'm not sure what kind of circuit would work (well). Can someone suggest a circuit design (with component values) for the purpose? Thanks.
Replacing a headphone cord antenna with with an external one: how to do it?
Sep 17, 2006
3 Replies
You need a choke and a capacitor, the choke to run the headphone from and the capacitor to connect to the antenna.
I would connect the antenna to the common connector on the headphone plug. The only difference in the headphone circuit is the actual resistance of the phone coils (8 ot 30 ohms). The headphones will still be part of the antenna system.
Dave
connect the antenna to the common (back conductor of the plug) wind the headphone cable through a ferrite core a dozen timnes or so.
you may get a better result connecting the antenna to battery negative instead.
Bye. Jasen
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