<div dir="ltr">I also had issues on 40 and 80 causing the USB fobs to have problems. My solution was to add big ferrites with multiple turns on both ends of the USB cable and individual ferrites on each audio line and control line (multiple turns) at both ends of the cable between the USB device and the radio, and also a big ferrite at each end of the USB device to radio cable with multiple turns of the entire cable. Also I found that there are 2 different grounds in the USB fobs. The ground that goes to the audio out jack is different than the ground that goes to the audio in jack. I use only the ground that goes to the audio in jack. After all this I was able to run 100 watts on 80 and 160 with no problems. The only grounds between my computer and the radio are that both use 3 prong 120volt AC power cords that are plugged into the same UPS, and the small ground wire in the USB device to radio cable described above. The radio is only about 3 feet from the computer but the cable is about 8 foot long so that I could make all the turns through the ferrite core. <div>
Chuck<br><div class="gmail_extra">
<br><br><div class="gmail_quote">On Tue, Feb 11, 2014 at 4:26 PM, Ken <span dir="ltr"><<a href="mailto:ke2n@cs.com" target="_blank">ke2n@cs.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<div>My understanding is that a USB port looks for the voltage dip caused by connecting your device - USB devices are supposed to have a capacitor on the +5 line just to cause a surge of current on connection. If you re-plug before it discharges, the port probably will not initialize properly.</div>
<div> </div>
<div>The other issue with the URI is that it basically connects the DC ground of the computer through to the DC ground of the radio. There are some 600 nH chokes that don't do much of anything below VHF frequencies. With one setup, I had an audio hum problem caused by ground loop currents. Connecting a short, direct, #10 wire between the radio chassis and the computer chassis neatly fixed this. It might help a bit with HF RFI too, possibly in addition to the ferrites on the other cables. The RF would still flow, but not through the URI.</div>
<div> </div>
<div>73</div>
<div>Ken</div>
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<td style="font-stretch:normal;font:11px/normal arial;background:rgb(249,249,249);font-size-adjust:none">Geoff <<a href="mailto:ars.w5omr@gmail.com" target="_blank">ars.w5omr@gmail.com</a>></td>
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<td style="font-stretch:normal;font:11px/normal arial;background:rgb(249,249,249);font-size-adjust:none"><a href="mailto:app_rpt-users@ohnosec.org" target="_blank">app_rpt-users@ohnosec.org</a></td>
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<td style="font-stretch:normal;font:11px/normal arial;background:rgb(249,249,249);font-size-adjust:none;padding:1px 10px 1px 9px">Subject:</td>
<td style="font-stretch:normal;font:11px/normal arial;background:rgb(249,249,249);font-size-adjust:none">Re: [App_rpt-users] Loosing TX</td>
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<td style="font-stretch:normal;font:11px/normal arial;background:rgb(249,249,249);font-size-adjust:none">Mon, 10 Feb 2014 12:03:20 -0600</td>
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<div>On 02/10/2014 08:34 PM, Doug Crompton
wrote:<br>
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<blockquote type="cite">
<div dir="ltr"><font face="Tahoma">Another thing to
consider on the DMK is RFI. They are very susceptible to it
especially higher power HF but be aware that any RF could
cause problems. I have had this happen at two different
locations. The fix was ferrites on the leads in and out. One
on each lead worked for me but more may be necessary depending
on the severity. You can also wrap multiple turns through a
single ferrite if they fit. <br>
<br>
This shows up a a locked interface and usb error messages that
in my case specifically said EMI? It might not always catch
that it is an EMI problem though so other errors might
indicate the same thing.<br>
<br>
Since the DMK is nothing more than a fancy USB sound FOB I
suspect any FOB might have this problem. Lead length both
audio and USB would also be a factor. </font><br>
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</blockquote>
<br>
Agreed. <br>
<br>
I am curious, though, what voltage is sent back to the USB buss from
the device.<br>
My reasoning is, that in -my- case, when this happened, I noticed
that if I pulled the USB cord, let it set for 15 or 20 seconds, then
plugged it back in, the green light lit up, and as soon as it
Transmitted, that URI died, again. Shutting down the machine, to
the point of letting the caps discharge, etc, then bringing
everything back up, plugged in, all worked flawlessly...<br>
<br>
until, at least, I RF'ed the system again with HF signals from 75
and/or 40m.... ~sigh~<br>
<br>
73 = Best Regards,<br>
-Geoff/W5OMR<br>
<br>
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