Thank you thank you!
That is wonderfully helpful information! I have
saved and printed it for future reference.
I hope that many others are helped by it as well.
doc
>> Can anyone recommend a laptop for this context?
>
>> 1. Sitting on top of a metal box that will house
>> HF & VHF-UHF gear as well as a scanner.
>> (must not radiate tons of RF noise)
>
> Most ham gear is shielded, and radiates little RF trash. It's the
> antennas that have the potential for problems.
>
>> 3. Runs natively from 12vdc.
>
> My IBM T22 and T41 work quite nicely from a Targus 12v universal
> power supply that I bought several years ago. The T41 lacks a
> serial port, so I put one of these in it. It works fine. We've
> used both on two Field Days as our CW logging computers.
>
> http://www.bb-elec.com/bb-elec/literature/dsp-100_2103ds.pdf
>
> At my old QTH, I had several HF antennas within 10 ft of the
> laptop and never heard RFI on HF. I DID, however, hear trash on 2
> meters CW or SSB when I moved the mouse or panned the screen when
> the laptop was powered from AC, and I was never able to suppress
> it.
>
> Expect to do some serious work on your serial interconnection with
> any computer that you use, because virtually all have pin 1
> problems, and an antenna as close as in a mobile rig is likely to
> excite them. A pin 1 problem is when the cable shield (or signal
> return of an unbalanced circuit) goes to the circuit board rather
> than to the chassis. To fix it, use the shell of the DB9 as your
> shield connection and signal rather than pin 5.
>
> It also helps a lot to use twisted pair for the serial cable. I
> recommend CAT5 (or CAT6/7). Shielding helps a bit above about 20
> MHz, but makes no difference below that. Use one pair for each
> circuit in the RS-232 connection you are using. For a typical
> serial connection where only pins 2 and 3 are used for control
> with pin 5 as the return, use orange for pin 2, blue for pin 3,
> orange/white and blue/white for return (the shell of the DB9). If
> your rig(s) require other circuits, use the remaining pairs to
> connect them.
>
> The above precautions will virtually eliminate all RFI from your
> ham gear to the serial connection. With a "standard" serial cable,
> my Elecraft K2 would lock up the computer at about 12 watts
> loading a long wire running a few feet away. With this wiring, I
> could crank my Ten Tec Titan up to full power (1.5 kW) into the
> same antenna.
>
> I've never heard RFI FROM a serial connection to ham gear, but
> Ethernet puts out lots of RF trash throughout the HF spectrum, and
> should be avoided if possible. If you must use it, the RFI app
> note on my website will tell you how to suppress some of it.
> Follow the link to Publications.
>
> 73,
>
> Jim Brown K9YC
> http://audiosystemsgroup.com
--
Thanks! & 73, doc kd4e http://bibleseven.com
Ham Links: http://bibleseven.com/hl.html
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