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Re: [RFI] 12vdc native laptop

To: rfi@contesting.com, tvi-rfi-emi <tvi-rfi-emi@mailman.qth.net>,12VDC_Power@yahoogroups.com
Subject: Re: [RFI] 12vdc native laptop
From: doc <kd4e@verizon.net>
Reply-to: kd4e@verizon.net
Date: Wed, 24 May 2006 16:06:09 -0500
List-post: <mailto:rfi@contesting.com>
 > FoMoCo EMC wrote:
> When testing with the Grundig radio keep in mind that what you may find to 
> be objectionable may disappear by the time you have moved away the distance 
> equal to where your HF antenna may be mounted.  So you may be chasing an 
> issue that doesn't exist.

I am concerned that where most modern HF gear
is as much plastic and metal that the RFI from
the PC and accessories will not have to be anywhere
near the antenna to find a way in.  Entry could
be interstage.

> I am not promoting a specific manufacturer but we found a Power Bright 
> APS-600 12VDC to 120 VAC pure sine inverter that works with all of our test 
> instrumentation.
> http://www.powerbright.com/puresine_inverters.html

Will have a look, thanks!

> The quietest way to power the 
> laptop is to get the laptop manufacturers DC to DC cube that takes 12V to 
> 18.5V.  This eliminates the noise from a square wave inverter and the 
> laptop's power cube and actually runs quieter.

I have one.  Will have to test it.

It appears that the LCD displays may be of
concern in both laptops apart from the power
supply problems.

> I would expect more noise from a hardwired NIC than from an 802.11x wireless 
> LAN which operates in the 2.5 GHz range.

The IBM was noisy without any NIC installed.

> Were you refering to no difference in noise between AC and battery powered 
> for the laptop or the Grundig radio?

The Laptop was battery and non-battery powered,
the Grundig was battery powered in both tests.

I think I may have to shift my view to a mini-
pc.  They are natively 12v/5v, can be found in
properly rf-sealed metal cases, will be more
easily bypassed and modified and upgraded.

The challenge then will be a native 12vdc LCD
display that is rf-quiet.

The quest continues!

Thanks! & 73, doc kd4e  http://bibleseven.com
Ham Links: http://bibleseven.com/hl.html
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