RF Hash from IBM Laptop

[Cfzepp]

Wondering if any of the Elecraft gang would happen to know if I can safely
power my IBM 380D laptop from a 13.8 VDC power supply without causing any harm
to the laptop.  I use this laptop exclusively for my logging.  The factory wall
supply is like most laptop supply's, it's a switching supply and it creates
lots of RF hash that I can hear in the receiver.

73, Don

WA9TGT / Donnie Garrett / Muncie, IN
ARCI #6447, ARS #1717, AmQRP, ECI-QRP #001
K2 #4003, K2 #3186, K1 #1806, K1 #0416, SW-30+, DSW II - 40
LDG Z-11 Auto Tuner, 102' CF Zepp fed with 300 Ohm Line
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[n6wg]

Hi don
I have two laptops here, and both can be run from an external battery
source.
HOWEVER, I need to run them through a small inverter to bring the
voltage up to around 13.8v.  I checked this with my variable
voltage bench power supply to find out where the laptop switched
from external power to internal.  It is usually above normal
battery voltage by 1-2 volts, hence the small inverter.

I built the one from Sam Ulbing, N4UAU.  It was written up in QST
as "My All-Purpose Voltage Booster".  He sells the kit for a very
reasonable price.  You can find him on the web under his call.

 I used mine on Field Day, and it was extremely quiet.  Not a trace of hash
anywhere.  A side benefit in running on batteries in the field is that the
converter is regulated.  As the input voltage drops, the output stays
pretty near constant.

This would not be a problem in the shack with a fixed supply.  I suggest
you check your laptop using a variable voltage power supply and find
out how low you can go before it switches over to the internal battery.

Good luck and 73
Bob N6WG

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[Doug Faunt N6TQS [phone]]

"Bob Tellefsen" <[hidden email]> writes:
>
> I built the one from Sam Ulbing, N4UAU.  It was written up in QST
> as "My All-Purpose Voltage Booster".  He sells the kit for a very
> reasonable price.  You can find him on the web under his call.
>

I've not having any luck finding Sam's site with Google, nor via the
QRZ reference, and it's been that way for at least a couple of weeks.

I have a couple of his kits, and they work well.

73, doug

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[Ron D'Eau Claire-2]

Vivisimo.com usually works a lot better for me as a search engine.

Plugged it in there and it came back  with N4UAU's home page which is "down"
and  this  link straight to details of the power supply:

http://tinyurl.com/5wjrh

Ron AC7AC

-----Original Message-----



"Bob Tellefsen" <[hidden email]> writes:
>
> I built the one from Sam Ulbing, N4UAU.  It was written up in QST as
> "My All-Purpose Voltage Booster".  He sells the kit for a very
> reasonable price.  You can find him on the web under his call.
>

I've not having any luck finding Sam's site with Google, nor via the QRZ
reference, and it's been that way for at least a couple of weeks.

I have a couple of his kits, and they work well.

73, doug



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[Ron D'Eau Claire-2]

Well, DANG! If I'd finish a message before hitting SEND it'd help.

Since N4UAU's site is down, you can get the schematic and lots of info (a
LOT of info if you speak French) here:

http://tinyurl.com/5f943

It's the complete construction info in French but the schematic is in
English.

Also, other references say the circuit was published in QST in 1997.

Ron AC7AC



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[Paul Tibbetts]

Sam can be reached at [hidden email] or you can find him any morning at 0700
Eastern on 7050 - Waterway CW Net.
Paul K1PT
----- Original Message -----
From: "Ron D'Eau Claire" <[hidden email]>
To: <[hidden email]>
Sent: Sunday, August 29, 2004 2:59 PM
Subject: RE: [Elecraft] RF Hash from IBM Laptop


Vivisimo.com usually works a lot better for me as a search engine.

Plugged it in there and it came back  with N4UAU's home page which is "down"
and  this  link straight to details of the power supply:

http://tinyurl.com/5wjrh

Ron AC7AC

-----Original Message-----



"Bob Tellefsen" <[hidden email]> writes:
>
> I built the one from Sam Ulbing, N4UAU.  It was written up in QST as
> "My All-Purpose Voltage Booster".  He sells the kit for a very
> reasonable price.  You can find him on the web under his call.
>

I've not having any luck finding Sam's site with Google, nor via the QRZ
reference, and it's been that way for at least a couple of weeks.

I have a couple of his kits, and they work well.

73, doug



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[Jack Brindle]

BE VERY CAREFUL DOING THIS!!!!!

This advice is specific to a single product form one manufacturer. Each  
laptop manufacturer has different battery maintenance circuitry, and  
they operate off different voltages, usually NOT 13.8V! Input voltages  
tend to vary between 12 v and 30 v depending on manufacturer. As an  
example, Apple PowerBooks and iBooks need about 25 volts. Applying 20V  
to a 12V input WILL cause undesired effects. Applying 12V to an 18V  
input MAY cause undesired effects.

Also, be sure that any power adapter you use will provide enough power  
to run the laptop. Laptop power supplies started out at about 20 watts  
many years ago, and generally run around 45-65 watts these days.

I would STRONGLY advise that anyone wanting to run their laptop from a  
12V battery source purchase a commercial power adapter for their  
laptop. These are available from many sources, including your local  
neighborhood computer store.

On Aug 29, 2004, at 11:14 AM, Bob Tellefsen wrote:

> Hi don
> I have two laptops here, and both can be run from an external battery
> source.
> HOWEVER, I need to run them through a small inverter to bring the
> voltage up to around 13.8v.  I checked this with my variable
> voltage bench power supply to find out where the laptop switched
> from external power to internal.  It is usually above normal
> battery voltage by 1-2 volts, hence the small inverter.
>
> I built the one from Sam Ulbing, N4UAU.  It was written up in QST
> as "My All-Purpose Voltage Booster".  He sells the kit for a very
> reasonable price.  You can find him on the web under his call.
>
>  I used mine on Field Day, and it was extremely quiet.  Not a trace of  
> hash
> anywhere.  A side benefit in running on batteries in the field is that  
> the
> converter is regulated.  As the input voltage drops, the output stays
> pretty near constant.
>
> This would not be a problem in the shack with a fixed supply.  I  
> suggest
> you check your laptop using a variable voltage power supply and find
> out how low you can go before it switches over to the internal battery.
>
> Good luck and 73
> Bob N6WG

- Jack Brindle, WA4FIB
------------------------------------------------------------------------
---------------------

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