I'm building an isolation box (between K2 and computer with external
soundcard) for digital operations, containing two 1:1 transformers and
voltage divider resistors. The box is metal. All input and output sockets
are 3.5mm mono and are grounded to the box, hence all input and output
braids are
McPherson
Sent: Monday, February 22, 2010 5:32 AM
To: elecraft@mailman.qth.net
Subject: [Elecraft] K2 - Isolation box construction for digital modes
I'm building an isolation box (between K2 and computer with external
soundcard) for digital operations, containing two 1:1 transformers and
voltage
Euan,
Your grounds should not be connected between the K2 and the computer -
that will un-isolate your isolation box. At the isolation box, use
stereo plugs and jacks at your interface box and connect the
transformers to the tip and ring. Similar if you are using an
opto-isolator on the PTT
My instincts would agree with Bob on this question.
You might consider using stereo jacks with (Ring Tip) only wired and
use the GND as sheilding.
Or you could omit the connector and wire direct out with a rubber
grommet in the box wholes.
N1BBR
I would buy a) isolated jacks, b) mount regular jacks in plastic to
isolate them, or c) use an all plastic box to isolate them. That was
you don't have to remember to use a specially wired cable to preserve
the isolation.
Tim, N9PUZ
On Monday, February 22, 2010 11:04 AM [GMT+1=CET],
dw wrote:
Hello Euan,
When I built my interface box here (years before K3's were available - HI), I
did
have ground loop problems. I floated all the grounds in all the cables and did
NOT connect them all together at the box. The only place they were grounded
was
at the mic connector on the radio.
My metal isolation box shares ground with the computer. That way I can
use normal audio jacks and cables. On the other side, I use a DB9
connector to isolate the box from any wires going to the radio. My PTT
connection is isolated via an optoisolator (4N33), requiring another DB9
to the
You would be well advised to read Computer to Radio Interfacing - You
Don't Need An Expensive Interface!
http://www.audiosystemsgroup.com/HamInterfacing.pdf, by Jim Brown, a
frequent contributor to this list and an expert on interference to audio
systems.
Basically, throw away the
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