[Elecraft] Elecraft KX3 Owner's Manualnowavailable(*preliminary*)

[Oliver Dröse]

Hi Jim,

you are correct about lower voltages on "modern" computers. Nevertheless the 
specs are higher and even 10-12 V is too much for most microprocessor pins. 
And I've seen a lot of ham shacks where *old* computers are still in use 
that have real serial ports with correct levels (as per sprecs). So to be on 
the save side we should not suggest people to apply RS-232 line levels 
directly even though it *might* work with some computers. ;-))

Vy 73, Olli - DH8BQA
http://www.dh8bqa.de




----- Original Message ----- 
From: "Jim Brown" <jim at audiosystemsgroup.com>
To: <elecraft at mailman.qth.net>
Sent: Tuesday, March 06, 2012 6:36 AM
Subject: Re: [Elecraft] Elecraft KX3 Owner's 
Manualnowavailable(*preliminary*)


On 3/5/2012 12:58 PM, Oliver Dröse wrote:
> you should*NOT*  apply RTS directly to the GPIO pin! RS-232 levels go up
> into the ±20 volts region per specs

Not in recent recorded history!  So-called RS-232 interfaces started
getting cheapened many years ago (before they went away and were
replaced by USB), and one of the first things to go was output voltage
swing. Think about the voltages available in a laptop, for example. I'd
be very surprised to see more than 10-12V on anything other than an
industrial RS232 interface, and less  on most laptops.

73, Jim K9YC
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