Went on the local 10 m net tonight. RF hash audible as I lowered the
power down to the "1/3" point (I have to dig out the watt meter to
find out what that was).
Crystal clear as soon as I disconnected ACC1 (with 4 turns of the
cable through a #31 toroid.
On Wed, Jan 1, 2014 at 1:51 PM, Peter Laws <plaws@plaws.net> wrote:
> 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
> problem.
>
> Swap in the DK-II and I boom - RF on the audio.
--
Peter Laws | N5UWY | plaws plaws net | Travel by Train!
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