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Re: [RFI] DigiKeyer II

To: jim@audiosystemsgroup.com
Subject: Re: [RFI] DigiKeyer II
From: Peter Laws <plaws@plaws.net>
Date: Wed, 1 Jan 2014 13:51:45 -0600
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
On Tue, Dec 17, 2013 at 8:50 PM, Jim Brown <jim@audiosystemsgroup.com> wrote:
> Hi Peter,
> See comments interspersed.

Likewise.  FINALLY got time to do something about this.  Meantime, I
bought some ferrite.

> A connection to earth is NOT part of a solution to RFI.  Proper bonding of
> equipment IS.  That includes short fat copper (#10, or copper braid stripped
> from transmitting coax) from every chassis to every other chassis that is
> interconnected. In your case, that means from the computer to the microHAM
> to the 746. The rig must also be bonded to the power system ground, and to
> all other grounds in your home.

All items mentioned have thick braids to a copper bar at the back of
the desk.  DK-II, IC746Pro, Power supply, PC.

Bar is connected to ground rod outside window, though the braid is
suspect, of course.  I picked up 25' of  6 ga at the local bigbox but
balked at the price of ring terminals (over a buck a piece?), so
that's not installed quite yet.  There are TransiTraps on each of the
feedlines that are also connected to the ground rod you say isn't
important for RFI.


> Maybe a Pin One Problem, but also a possible power problem.  How are you
> powering your microHAM?  The wall wart that came with it, or from the 12V
> bus?  Use the wall wart, not 12V.

No wallwart.  USB, but not powered that way.  Pulls 13.8 V dc from the
ACC1 on the radio.

>  Is this problem present on all bands, or only on 17M?  Take one of your
> ferrite cores and wind 4-5 turns of the ACC1 cable through it. Do the same
> with the USB cable.

Bought 2.5" OD Fair Rite toroids, 4 ea mix 31 and mix 43.  Bought some
snap-ons, too, just for fun.

Got 4 passes through a #31 toroid.  Not sure if a 5th is possible.

No change, though, I still hear it through the headphones.  I'll find
someone to give me a report after I run some errands, but I already
know the answer - it will go away the instant I unplug ACC1.

As I noted a while back.  Same PC, same radio, same antennas, same
ground using a RigBlaster Plus had no audio problems ever.  The RB+
has no audio device in it, or USB, and is powered off shack power
supply ... but all audio, coming and going, passes though it.  Never a

Swap in the DK-II and I boom - RF on the audio.
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