[TowerTalk] Need help with HF problems

[Jim W7RY]

How about something as simple as a bad coaxial cable from the station move?

73
Jim W7RY



--------------------------------------------------
From: "Jim Brown" <jim at audiosystemsgroup.com>
Sent: Monday, May 30, 2011 11:22 AM
To: <towertalk at 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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