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Re: [RFI] HF Problems

To: rfi@contesting.com
Subject: Re: [RFI] HF Problems
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Wed, 17 Nov 2010 18:53:56 -0800
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
On 11/17/2010 4:36 PM, pwjmrj@quixnet.net wrote:
> I have an ICOM IC-738 HF Radio, connected to an ICOM IC-PW1 Linear.
> When running barefoot, I do not cause IF interference in our home.  However,
> the minute I turn on the linear, my signal bleeds into the phones, radios
> and TVs.  I have installed a quality low pass filter as well as chokes on
> every electronic item.  Much to my dismay, these steps haven't eliminated
> the problem.

Study my RFI tutorial.  http://audiosystemsgroup.com/RFI-Ham.pdf   
Underline the word STUDY. These concepts are complicated, and it may 
take several careful readings to get your head around them, but you need 
to do that to solve your problems.

As Kirk has hinted (by the questions he's asking), there are things you 
can do with your antenna system to minimize problems, but the CAUSE of 
these problems is poor equipment design/construction of the gear that 
receive interference. The tutorial describes the common coupling 
mechanisms and provides many solutions, both general and specific, for 
taming them.

Another thing that is VERY helpful is to run the amplifier at various 
reduced power levels and note how far you must reduce the power to kill 
the interference with each product that receives it.

And another VERY important thing.  NEVER, NEVER use ALC to set the drive 
level to the power amp. ALWAYS set the drive level with the RF OUTPUT 
control of your transceiver. Most amps generate LOTS of trash when you 
use ALC to set power level.  That trash comes in the form of both 
splatter and harmonics.

As to problem #1 -- I don't know anything about that specific rig or 
power amp. But your symptoms suggest either a power supply problem or a 
control system problem.

73, Jim Brown K9YC
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