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Re: [RFI] RF Quiet Laptop for Mobile Console?

To: RFI List <rfi@contesting.com>
Subject: Re: [RFI] RF Quiet Laptop for Mobile Console?
From: doc <kd4e@verizon.net>
Reply-to: kd4e@verizon.net
Date: Fri, 19 May 2006 08:50:06 -0500
List-post: <mailto:rfi@contesting.com>
> Not long ago, I tried running digital modes using a KAM-XL hooked up to a 
> Fujitsu P5020 "Lifebook" laptop. This actually worked well -- quieter than my 
> e-Machines T2642 -- until I hooked up a power supply.  Both the DC and AC 
> supplies are of course switchers, putting out 16 volts the computer needs.  I 
> am considering tapping off 16 volts from the unregulated part of an analog PS 
> for this application when at home. Meanwhile, carrying an extra battery gives 
> me almost 8 hrs of computer life, and an optional extended-life battery can 
> replace the CD-drive  for (IIRC) about 11 hours total, if that can be 
> accepted. 
> I have not gotten "a round tuit," but I suspect the computer might still work 
> on 12 volts, if not charge the battery from it; the battery voltage is only 
> 10.8 volts.  Some years ago there was an article in a Ham magazine about one 
> Amateur who modified a laptop's battery to accept 12 volts. Among other 
> things, this required adding a voltage regulator inside a battery pack.  
> Alternatively, there is a Ham (name, call forgotten) who builds and sells 
> RF-quiet switching power supplies for such applications.  Or you can yourself 
> shield and filter one built by the computer manufacturer.
> Cortland KA5S

Thank you for that report!

I am looking at the purchase of a Black & Decker
cordless trimmer.  It uses rechargeable 18v batteries
and comes with two of them.

I believe that most laptops will happily run off
18vdc. (I fear that 12vdc/13.8-14.5 would cause a
higher-than-design current draw resulting in over-
heating damage to thin traces and low-tolerance

This would avoid the purchase of costly extra
proprietary laptop batteries.  I also understand
that the trimmer's 18v battery works on many of
B&D's other tools.

This would also avoid fussing around trying to
find a properly engineered dc-dc converter that
does not generate illegal RF interference to
legal services.  (BTW:  This is the an avenue
for enforcement, it just has not used yet.)

During a storm one could just borrow the 18v
batteries from the tools and keep the laptop
running for quite a while ... presuming that one
remembered to keep them charged!

I have to look for a solar charger that prevents

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