Jim,
With respect, the microHAM products were done correctly with
regard to any "pin 1 problem." The radio interface cable is
shielded with all shields connected to the shell of the DB37
(connected to the case and circuit ground plane). The audio
connections to the radio are all floating ("pin 1" is not
connected to the common ground) and the unbalanced connections
to the computer soundcard are transformer isolated. The USB
connection to the computer is floating with respect to the
rest of the device. The only connection between the USB core
and the rest of the service are via high isolation optical
isolators. The USB circuit ground (common) is isolated from
the common/case in the rest of the device.
The ONLY time there is a "pin 1" issue is when the radio
manufacturer screws up (e.g., Yaesu) and connects the shield
of the mic cable to pin 7 of the Foster connector (mic return)
instead of pin 5 (chassis) or an aftermarket manufacturer
(e.g. Heil) connects the shell of the Foster connector to
pin 7 (mic return) instead of pin 5 (chassis). In both cases
this is the equivalent of connecting pins 1 and 3 of the
XLR!
This issue is even more "fun" with the new microKEYER II as
its rear panel microphone input is balanced and floating for
hum/common mode rejection. The Yaesu/Heil connections cause
signals that should be common mode and therefore be rejected
by the preamplifier to be converted to differential mode and
effectively enhance RFI sensitivity.
> >microHAM's keyer interface with WriteLog problems. Random speed
> >changes (in both directions), skipping the first character sent by
> >WriteLog under certain conditions, etc.
You do not indicate what version of WriteLog or microHAM Router
was in use. However, Router 5.0.x is a complete ground up revision
that has eliminated several WinKey issues with all of the contest
loggers as well as resolving buffer handling issues related to dual
core and hyper threading CPUs that were caused by an old (written
prior to multi-core CPUs) third party programming library. Several
of the issues have been discussed previously along with work-around
information to disable the process swapping that created the
problem with the old code.
The random speed changes are most often associated with the use
of <<< or >>> to change speeds within a CW macros - particularly
if a macro is "dumped" with the <esc> key. The <<< and >>> use
"temporary" speed changes within WinKey. Certain WinKey commands
will reset the device to the speed set by the "pot" or the last
direct speed setting command and can result in a potentially
unexpected speed change.
73,
... Joe Subich, W4TV
microHAM America
http://www.microHAM-USA.com
http://groups.yahoo.com/group/microHAM
support at microham.com
> -----Original Message-----
> From: writelog-bounces at contesting.com
> [mailto:writelog-bounces at contesting.com] On Behalf Of Jim Brown
> Sent: Tuesday, November 06, 2007 10:33 AM
> To: WriteLog Reflector
> Subject: [WriteLog] RFI and Keyers
>
>
> This is a reply that I posted to email on the NCCC list this
> morning.
> The original post complained of buggy control between a Microham
> keyer and Writelog. I don't think it's a WriteLog problem.
>
> For a detailed discussion of the causes of this RFI, see
> http://audiosystemsgroup.com/RFI-Ham.pdf
>
> On Tue, 6 Nov 2007 01:46:01 -0800, Michael Shapiro wrote:
>
> >microHAM's keyer interface with WriteLog problems. Random speed
> >changes (in both directions), skipping the first character sent by
> >WriteLog under certain conditions, etc.
>
> >Most probably it's a WriteLog interface to blame...
>
> I'd put my money on pin 1 problems in the keyer. I haven't done
> actual testing, but AE6RF used one at my QTH over the weekend, and
> it was still here when I returned from N6IJ. After I tore down his
> station to make room on my operating desk, I opened up the Microham
> and studied its construction. I can't find a single connection
> between a cable shield and the chasssis.
>
> 73,
>
> Jim Brown K9YC
>
>
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>