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Re: [RFI] 12vdc native laptop

To: rfi@contesting.com
Subject: Re: [RFI] 12vdc native laptop
From: "FoMoCo EMC" <fomoco_emc@hotmail.com>
Date: Wed, 24 May 2006 15:18:24 -0400
List-post: <mailto:rfi@contesting.com>
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 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 


I haven't seen a 12V laptop  since the 386 days.  Compaq had some a few 
years ago that would run on 12 volts but wouldn't charge the batteries and 
they didn't broadcast that feature either.  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 would expect more noise from a hardwired NIC than from an 802.11x wireless 
LAN which operates in the 2.5 GHz range.

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

>From: doc <kd4e@verizon.net>
>Reply-To: kd4e@verizon.net
>To: 12VDC_Power@yahoogroups.com
>CC: tvi-rfi-emi <tvi-rfi-emi@mailman.qth.net>,RFI List <rfi@contesting.com>
>Subject: Re: [RFI] 12vdc native laptop
>Date: Tue, 23 May 2006 23:16:40 -0500
>Larry D. Barr wrote:
> > I've never seen a native 12 VDC laptop. Of course, that doesn't mean
> > they don't exist <G> I've had really good service from the Lind
> > Electronics "Auto/Air Adapters". They make for just about everything. I
> > have one for each of the three laptops I have and they work great. Seem
> > to be quite efficient too. I cut into the input line and fit Anderson
> > PowerPoles inline, so I can use 'em with the RigRunner in the shack or
> > just plug the cigarette lighter plug back on if I need to.
> >
> > http://www.lindelectronics.com/
>I am going to have HF, VHF, & UHF gear in a box
>between the seats and the laptop will sit right
>on top of that same box.
>My dc-dc converter is multi-voltage 15, 16, 18, 19,
>20, 21v 4.0A 65W max  P/N:  GW-P006VB
>I have yet tested it with the HF rig I plan to take
>mobile because I haven't bought the rig yet!  :-)
>I will try it close to the mobile VHF/UHF rig.
>Using a little Grundig 100PE mini-handheld this laptop
>wipes out everything from AM-BC through 18MHz at a
>distance of several inches and raises the noise floor
>considerably a couple of feet away -- that is on AC
>power.  No difference on battery power.  It is
>hardwired to the Internet router so it is not a wireless
>nic generating the noise.
>The IBM ThinkPad 600X is even worse -- without being
>powered on!  And the RFI increases when powered on.
>I cannot imagine that some of the noise from the
>dc-dc converter won't get into at least the HF rig.
>Have to hit the hay but will test my dc-dc converter
>I know that there are mini-pc's now that come
>with 12vdc power supplies.  I may have to look
>to see what those 12vdc input power supplies
>are outputting.
>As I recall a non-laptop requires 12vdc and
>5vdc, no 18 or 19v so maybe that is the solution?
>I also use Powerpoles everywhere now.
>Thanks! & 73, doc kd4e  http://bibleseven.com
>Ham Links: http://bibleseven.com/hl.html
>RFI mailing list

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