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[Orion] AC Line Noise and Possible Cure

To: tentec@contesting.com, orion@contesting.com
Subject: [Orion] AC Line Noise and Possible Cure
From: N0KHQ@aol.com
Date: Sat, 11 Dec 2004 21:02:39 EST
List-post: <mailto:orion@contesting.com>
Man, been a busy day today.
 
This is why you want to use a dedicated 115VAC circuit for you ham  gear.
 
I published this about 9 months ago on the Jupiter Yahoo Group, here it is  
again!
 
How AC Noise is Created 

Electrical noise is a natural phenomenon. Along with the fundamental  120V 
60Hz power, reactive currents are on the service mains neutral and ground. 

Reactive currents represent "unused" energy that has been discharged  onto 
the power lines from the impedance load as the source voltage modulates.  Each 
piece of connected equipment in your home or office adds to the total  reactive 
current on the neutral wire, which in turn is connected to the  electrical 
systemâs ground. The level of these reactive neutral/grounding  currents can 
be 
considerable. In many cases in the past, there have been high  enough levels 
of reactive currents present in the power to crash data processing  systems. 
Historical evidence attesting to this fact is overwhelming. 
 
Data processing facilities have long had problems with AC power. Itâs no  
wonder that the audio industry is finding out that digital sound reproduction 
is  
no piece of cake. In other related areas such as digital broadcasting,  
malfunctions from poor power often prove to be the "Achilles Heel" of the  
system, 
particularly where extremely high bit rates and wide bandwidths are  used. 
Compressed noise can cause real problems. 
 
Electronic power supplies have long been known to create these reactive  
currents. In the electrical power industry, an entire segment of that field has 
 
grown up around the study of "power quality." Power quality (PQ) has much to do 
 with the purity of AC power as it affects the operation of sensitive  
electronics.

Aside from reactive currents, there are other PQ  issues involved that can 
affect equipment performance. Among them is Power  Factor. Whenever the true 
power used by a load equals something less than the  apparent power being 
supplied, reactive currents make up the difference. 
 
This ratio between true power and apparent power is called "Power Factor."  
Ideally the ratio would be 1:1. However, the presence of reactive current means 
 that some portion of the power that is present has shifted phase. This is 
due to  the effect of reactive current from a typical non-linear (impedance) 
load. Some  of the voltage is lagging 90 degrees from the fundamental voltage 
phase. This  shift in voltage away from the active current phase means that to 
that extent,  simply, there is no power present. Voltage and current must be in 
phase for  power to exist -- for electricity to actively create an effect. Low 
power factor  means that the efficiency of equipment power supplies will be 
affected. 
 
Often studio owners will comment that their equipment sounds better at  
night, a symptom of heavy commercial use on the power system during daylight  
hours 
and an indication of poor power factor.
 
I got tired of listening to the wifes hair dryer, tired of listening to the  
garbage disposal and what other stuff she was turning on upstairs through my  
rigs.
 
Soooo!
 
What I use to help with these stray reactive currents is an 120VAC Line  
Filter Model 473 / 40amp as sold by Array Solutions, cant remember how  much it 
cost. All of my ham (Orion, TS-950DX and  IC-756proll) equipment, 50amp power 
supply and 8 pieces of sound  reinforcement equipment is running through this 
AC 
filter from a dedicated  115vac 20amp circuit. The AL-80B is on a dedicated 
220vac circuit (shared with  the clothes dryer, but never run at the same time).
 


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