FW: [Elecraft] MicroHam microkeyer

[Don Wilhelm]

Folks,

Jack Brindle sent this privately, but I must say he is correct - a computer
or external device that connects to pin 1 can create a ground loop.  While
that will not likely harm anything electrically, it may make functions 'work
strangely'.

Jack and I both did a bit of web research of the real RS232 standard, and we
discovered that the EIA standard specifies the DB25 conector, but nowhere
could we find the DE9 connector in the standard unless it has been updated
beyond the RS232-D level - so the use of that connector is not really a
standard, but it certainly is commonplace.

One should not assume that any particular connector implies any kind of
standard.  As an example, the 25 pin DB25 connector is used both for a real
RS232 serial port and on most PCs  as a printer port.


73,
Don W3FPR

> -----Original Message-----
> From: Jack Brindle [mailto:jackbrindle at earthlink.net]
> Sent: Monday, October 24, 2005 11:00 AM
> To: w3fpr at arrl.net
> Subject: Re: [Elecraft] MicroHam microkeyer
>
>
> Don;
>
> Might want to rethink just one pin of that. A connection from the
> computer to pin 1 of the KIO2/KPA100's DE9 will probably create a
> ground loop. Only connections to pins 2, 3 and 5 are needed.
>
> Pin 1 is the ground for the non-RS232 stuff (Auxbus, etc.).
>
> On Oct 24, 2005, at 4:38 AM, Don Wilhelm wrote:
>
> > If the Microkeyer has connections only to pins 1, 2, 3 and 5 of the
> > 9 pin
> > connector, one can safely plug it into the K2 directly.
>
> - Jack Brindle, W6FB
>