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Re: [RFI] 12vdc native laptop

To: kd4e@verizon.net
Subject: Re: [RFI] 12vdc native laptop
From: <dgsvetan@rockwellcollins.com>
Date: Wed, 24 May 2006 14:16:11 -0500
List-post: <mailto:rfi@contesting.com>

Regarding your test of the laptop and the Grundig:

1.  Keep in mind that radiated emissions from computers are usually
measured at a distance of 3 meters from the computer.  You probably will
not have that much separation distance anywhere within your set-up.   Also,
radiated emissions below roughly 30 MHz are not measured at all.

2.  If the Grundig was using its integral antenna while you had it inches
away from the laptop, you were using an RFI detector, not a receiver.

Per the on-going thread about the power converters and such:  There are NO
SERIOUS radiated emission requirements (of which I am aware) on power
supplies (including converters) other than specified for military use and
tested per MIL-STD-461E RE102 (or equivalent) requirements.  (The FCC Class
B limits for switching power supplies allow way too much junk to radiate
for communications applications.)  The commercially available switching
power supplies, such as those from Astron, MFJ, Alinco,  and others,
generally exceed by far the FCC Class B conducted and radiated emissions
requirements because their intended application, powering communications
systems, DEMANDS that they be "clean" units, not because of any particular
rules and regs.  I own an Astron SS-30M, and it's got more ferrites and
by-passes in it than anything short of a mil-spec unit I've seen.  If you
want clean power, you'll probably have to clean up a power converter
yourself, including packaging it into an all metal enclosure and passing
all input and output leads through decent line filters.  As for the
computer, keep receiving antennas as far as possible from it.  You may well
find that the display is a disaster for making noise.  Good luck.

73, Dale

             >                                                          To 
             Sent by:                  12VDC_Power@yahoogroups.com         
             rfi-bounces@conte                                          cc 
             sting.com                 tvi-rfi-emi                         
                                       <tvi-rfi-emi@mailman.qth.net>, RFI  
                                       List <rfi@contesting.com>           
             05/23/2006 11:16                                      Subject 
             PM                        Re: [RFI] 12vdc native laptop       
             Please respond to                                             

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
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