> -----Original Message-----
> From: WA3GIN
> Subject: WHINE on XMIT using IC2100
>
> A local ham buddy here is having a hell of a time trying to
> rid his 2m audio xmit signal of whine from his alternator.
>
> I would have thought that the measures he took above would
> have solved his problem.
Nope. He needs a healthy choke in his +12VDC lead. Find an old filament
transformer with some "heft" -- perhaps a 10A winding or so. Put the two
ends of the winding in series with his +12VDC lead. Leave the primary leads
open (but covered with tape or other insulation). Mount it behind the 2M
rig, below the dash. Put a nice fat capacitor (100 microfarad electrolytic
or solid tantalum) across the 2M rig power terminals (i.e., on the
non-battery side of the filament transformer winding).
Your buddy is hearing the (normal) AC ripple voltage from his car's
alternator which is basically a 3-phase full-wave rectifier, unfiltered. So
he's hearing some multiple of engine rpm, and the filtering that's possible
inside his tiny 2M rig is totally inadequate to the task.
Bud, W2RU
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