[RFI] WHINE on XMIT using IC2100

[W2RU - Bud Hippisley]

> -----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