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[aprssig] desirable laptop computer features?

Stephen H. Smith wa8lmf2 at aol.com
Tue Oct 31 19:49:41 UTC 2006

rodpadmore at ns.sympatico.ca wrote:
> What are the most important features found in an APRS 
> friendly computer available in today's market place? Does anyone have 
> other suggestions such as brand and model? 
> Thanks to anyone that has an informed opinion on these questions. 73 
> de Rod.
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1)  Real serial ports!!!   This is critical to avoid the hassle with 
USB-to-serial converter "dongles". which have endless compatibility 
problems with some programs and operating systems. 

This is even more of an issue when using soundcard-based programs that 
use the handshaking lines of the serial port independently of the data 
flow in unorthodox ways, to key transmitter PTT lines, send CW and 
RTTY-FSK at odd rates like 45.45  baud, take in receiver squelch status, 

Unfortunately, virtually NO consumer mass-market laptops have serial 
ports anymore. You will have to go to higher-priced business and 
specialty-market machines to get real ports.  (This is why I just paid 
USD $1500 for a new Panasonic Toughbook CF-51 15" CoreDuo laptop through 
a specialty reseller,  instead of buying a similar consumer market 
machine for under $1000.)  

[Actually the Toughbook has other attributes that make it desirable for 
APRS.  It's designed to work reliably at high temps and to withstand 
dust, shock and vibration such as in a car or at field day .   Large 
numbers of Toughbooks are used as mobile terminals in police cars, 
delivery trucks, etc. ]

An alternative to the messy USB-to-serial devices is to buy (rather 
pricy) PCMCIA cards with real serial ports on them.  (Assuming the 
laptop still has "classic" PCMCIA card slots!)  On many machines these 
are being dropped in favor of multiple types of slots for flash memory 

2)  Decent sound system if you intend to use soundcard-based soft TNCs 
like the AGW Packet Engine or MixW.  Most laptops now lack a stereo 
line-level audio input. They only have a monophonic mic input.  This has 
two real disadvantages.   First the mic input is almost always far too 
sensitive for the audio levels coming out of a radio speaker or 
packet/aux jack, forcing you to kluge resistor attenuator networks in 
the cable to keep the mic input from overloading.   Second, you throw 
away the ability of programs like the AGW Packet Engine to create a 
dual-port TNC that can support TWO radios at once.  ( With a STEREO 
input, you can actually connect one radio and soundcard interface to the 
left channel, and a second one to the right channel at the same time.)

3) Other things being equal, a machine whose chassis power input from 
it's supplied "power brick" is 12-14VDC rather than the 19-20 VDC that 
is most common.   This gives you the option to operate directly from 12 
VDC power setups in cars, at field day, etc without DC-DC upconverters 
or worse 12DC-to-110VAC inverters with their attendent 
inefficiencies.     This was an unexpected pleasant surprise and bonus 
when I got the Toughbook. 

4)  PS/2 keyboard/mouse port.   These are beginning to disappear also in 
the face of the everything-USB juggernaut. Even if you don't use it for 
an external keyboard, the PS/2 port has traditionally been a handy 
source of +5 VDC for powering serial GPS devices, powering TinyTraks 
while being programmed, charging cellphones, etc.  


Stephen H. Smith    wa8lmf (at) aol.com
EchoLink Node:      14400    [Think bottom of the 2M band]
Home Page:          http://wa8lmf.com  --OR--   http://wa8lmf.net

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