The Isobar filter that I have has individual Toroid filters on each line
inside the metal box. Additional Toriod filters are between the stage 1 and
stage 2 outlets. Both the hot and common lines are individually filtered.
Even though it contains MOVs, It is not mill-of-the-run MOV surge protected
power strip. Hence the additional costs.
A brief description of the four outlet unit is at:
http://www.tripplite.com/en/products/model.cfm?txtModelID=3950
Disclaimer: I have no interest in Tripplite...just a satisfied user. Works
for me.
73s de Jim
W5IFP
> -----Original Message-----
> From: towertalk-bounces@contesting.com
> [mailto:towertalk-bounces@contesting.com]On Behalf Of Jim Brown
> Sent: Friday, June 08, 2012 11:08 AM
> To: towertalk@contesting.com
> Subject: Re: [TowerTalk] Mains Filter for 80M
>
>
> On 6/8/2012 8:41 AM, Jim Hargrave wrote:
> > I use an ISOBAR IB-4 dual stage line filter.
> > It is a combination noise and surge protector.
>
> Remember that shunt mode surge protectors (MOVs) are safe ONLY at the
> building service entrance (so-called "whole house" suppressors). When
> installed on branch circuits at at outlets, they are as likely to CAUSE
> equipment failure as to prevent it.
>
> I've put several RF line filters that "look good on paper" into
> enclosures and wired to connectors for use on Field Day and Califorrnia
> QSO Party county expeditions to clean up noisy generators. They have
> been totally ineffective for common mode noise, and the noise most
> likely to cause us trouble is common mode noise. What DOES work for
> common mode noise is to wind turns of the power cord through a suitable
> ferrite core. 12-14 turns through a #31 toroid would be just about
> optimum for 160-40M. 6-8 turns would be about right for the higher HF
> bands. A #43 core needs at least 14 turns for 80M, and works
> as well as
> #31 for the higher bands.
>
> What is equally important is proper bonding of all grounds and systems
> in your home and shack. That means bonding the power system ground to
> your shack ground, cable TV, satellite, telephone, etc. AND it
> can also
> help to use ferrite chokes on the Beverage coax, and any nearby wiring
> that can radiate noise into your antennas, including the Beverage.
>
> 73, Jim Brown K9YC
> _______________________________________________
>
>
>
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