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Author Topic: Cheap UK laptop: RFI free ??  (Read 4954 times)

Posts: 9

« on: September 23, 2011, 04:44:17 PM »

Hi all.
My home PC gives off nasty RFI on the lower bands, (up to 40 meters) and some nasty birdies higher up.

Not normally a problem but I need to buy a cheap laptop for mobile operations and I might as well use it in my shack and give my daughter my base unit for her school work at home.

I've looked around for metal cased laptops but they seem quire expensive and I don't need to spend that much money.

My question is, are there any UK amateurs using a new low end(ish) laptop that they reckon doesn't cause any RFI ?

With a serial port would be nice so I can connect to my K3 directly but that's too much to ask I think..

Laptops supposedly have better screening than most base units anyway, I hope!

Any suggestions appreciated, my daughter is also quite keen! hi hi..

Posts: 2243

« Reply #1 on: September 24, 2011, 01:34:16 AM »

HI Lain:
I would check out the laptop's power supply, that might be
the source of the birdies. It was. My old laptops have been immune to QRO RTTY
too, unlike my desktop, go figure.

Anyway, I took the mains-fed section of the laptop PS and sealed that
in a tight metal enclosure. Then after determining proper polarity,
I spliced in a 6-7 meter long "extension" cord to my laptop.
I curled up the excess lengths where necessary and added a few toroid chokes,
Then I stuck the enclosed laptop PS in a closet and ran the extension to my desk. Low and behold the birdies and PS generated noise stopped completely

But what REALLY surprised me was that I was STILL able
to run QRO without interference into my computer, interfaces, CI-V,
modems & peripherals.  I had figured that the "20 foot extension cord"
I built for my laptop  would have acted like an antenna for all that RF
on the it does for the desktop bu not the laptop.
Re: Getting A New Laptop:
NO new laptops have Serial ports, and depending on the OS, like
Windows 7, you might very well find yourself in a bad nightmare.

1) Finding USB-Serial Port Adapters for all your srial port ham devices
 that work with a 64 bit system like Windows 7 is ALMOST IMPOSSIBLE.
 No stores carry them. Oh,yes salesmen will "say" they will work. They LIE

I had to special order mine online with a FTDI Chipset and make sure they have the proper drivers, or the drivers are available.

2) Some older, but excellent quality serial designed software,
like the TERRIFIC RTTY contesting software WriteLog WILL NOT OPERATE
UNDER WINDOWS 7 unless the whole system is reconfigured by an IT professional.
(I just bought this nice Samsung laptop lat week. Hoped
to use it in the RTTY Contest.....NOT with WriteLOG I can't.

The OS's and their ever growing complexities (and SUCKING UP HUGE SYSTEM RESOURCES) is getting so OUT OF CONTROL
that soon NOTHING will be "Backwards Compatible" anymore.
(See any 64 bit ham programs on the horizon)

WHAT I AM GOING TO give this lovely, feature packed
broadband, but ham radio useless (for my ham needs) laptop to my
lovely XYL,and keep my eyes open for good deals on older
laptops in good condition running XP and such for my shack.

GL ES 73, Ken  AD6KA

Posts: 634

« Reply #2 on: September 24, 2011, 01:42:04 PM »

I can't help you with an RF free laptop but what I can tell you is that the Fujitsu Siemens desktop I bought for £56 quid last year has no problems. Extremely well designed and the construction and manufacture is superb. Have a look at the vast selection of well priced used laptops at and its free next day delivery. A helpful company.


Posts: 787

« Reply #3 on: September 29, 2011, 04:40:00 PM »

I've had a succession of IBM Thinkpad laptops that I bought used. My current shack computer is a Thinkpad T43. None of them put out any detectable RFI and just as importantly none of them were susceptible to RF from the 100W HF radio. They also have probably the best keyboards of any laptops out there.

Posts: 3746

« Reply #4 on: September 29, 2011, 05:36:32 PM »

hi Iain,

I also use Thinkpads, purchased used off lease from IBM,
for field day and in the home shack.

No problems at all.

73 james
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