[Elecraft] WAY OFF Topic question - Opto Isolator - USB - Weather

[Bob - AG5Q]

Hi Dan,

The cost of parts for an optically coupled  interface isn't much, but it
might take a long time to figure out where all the wires go since they
aren't documented.

Take a look at the electronics at the far end and see if  it can be mounted
so it's not connected to something that's grounded (like a metal tower). As
long as the sensor package isn't grounded a long way from your computer, it
should work. RS232 has a large signal level and pretty good noise immunity.
The baud rate shouldn't be set too high either since your required data rate
is low. A slow baud rate and caps from signal lines to ground might help.

73/ Bob - AG5Q


----- Original Message -----
From: "Dan Barker" <dbarker@visioncomm.net>
To: "Elecraft" <elecraft@mailman.qth.net>

> Anyhow, I bought this weather equipment, and the manufacturer says the
> reason the windspeed on the Weather station ($200) goes to 99MPH whenever
I
> plug in the RS232 connector ($150 option) to the computer (Never mind<g>)
is
> due to a ground loop. The fix is an "opto-isolator ($55 option).
>
> I objected originally to $150 for the RS232 adapter (especially since the
> software that comes with it is useless), but I REALLY OBJECT to $55 more
to
> fix what sounds to me like a design flaw.
>
> My question to the group (thanks for the BW) is:
>
>   Would some capacitors likely fix this? (choke didn't)
>
>  If I put my (100mhz) 'scope on the wires (it's only 4 wires,
undocumented,
> but most likely ground, transmit data, receive data, and mystery wire),
what
> should I look to see?
>
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