How about something as simple as a bad coaxial cable from the station move?
73
Jim W7RY
--------------------------------------------------
From: "Jim Brown" <jim@audiosystemsgroup.com>
Sent: Monday, May 30, 2011 11:22 AM
To: <towertalk@contesting.com>
Subject: Re: [TowerTalk] Need help with HF problems
> On 5/28/2011 2:27 PM, Magnus Aronsson wrote:
>> I have some HF problems.
>
> Several thoughts.
>
> First, virtually ALL computer sound cards, and virtually ALL powered
> speakers are notorious for being RFI DOGS. SERIOUS multi-turn ferrite
> chokes on audio cables and serious DC bonding from chassis to chassis of
> all of the gear in your shack can help keep RFI and noise out of your
> computer.
>
> Second, I would suspect some sort of problem in the AC POWER wiring.
> Something as simple (but REALLY BAD) as reversal of black and white (or
> white and green) an one or more power outlets. Maybe you didn't re-wire
> anything to move your station, but maybe you're plugged in to different
> outlets than you were before, and they were bad from the beginning.
> Remember that all power wiring is done by human beings, and, as a race,
> we screw up. :)
>
> Third, be sure that there is VERY SOLID bonding between your rigs, the
> AC power system, and EVERY ground in your home. (A BOND is simply a
> very robust, big, short connection between grounded objects). This sort
> of thing is REQUIRED by building safety codes in virtually all of the
> developed world. Not only does it make things more SAFE, it also greatly
> reduces problems with RFI, hum, buzz, and other forms of noise.
>
> Fourth, use robust coax chokes at the feedpoints (that is, up in the
> air) of all antennas to keep RF off the coax. This helps with RFI, and
> it also minimizes the RF noise that the antenna hears.
>
> For more detailed advice, study the tutorials at
> http://audiosystemsgroup.com/publish.htm especially the one on RFI
> and ham radio. Study the chapter on Solving Problems in the Shack, and
> see the section on coax chokes for details on that. Also study the
> beginning stuff to understand how RFI happens.
>
> 73, Jim Brown K9YC
>
>
>
>
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