Re: [App_rpt-users] App_rpt-users Digest, Vol 60, Issue 39
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. 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. 73 Ken Attached Message From: Geoff <ars.w5omr@gmail.com> To: app_rpt-users@ohnosec.org Subject: Re: [App_rpt-users] Loosing TX Date: Mon, 10 Feb 2014 12:03:20 -0600 On 02/10/2014 08:34 PM, Doug Crompton wrote: 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. 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. 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. Agreed. I am curious, though, what voltage is sent back to the USB buss from the device. 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... until, at least, I RF'ed the system again with HF signals from 75 and/or 40m.... ~sigh~ 73 = Best Regards, -Geoff/W5OMR
Good point. And if you were to lose the ground between your radio and its power supply the radio would try to find its high current ground through the URI back through the computer power ground. In any event bad things could happen. I will have to put a ground between the radio and computer. 73 Doug WA3DSP http://www.crompton.com/hamradio To: app_rpt-users@ohnosec.org; ars.w5omr@gmail.com From: ke2n@cs.com Date: Tue, 11 Feb 2014 17:26:59 -0500 Subject: Re: [App_rpt-users] App_rpt-users Digest, Vol 60, Issue 39 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. 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. 73 Ken Attached Message From: Geoff <ars.w5omr@gmail.com> To: app_rpt-users@ohnosec.org Subject: Re: [App_rpt-users] Loosing TX Date: Mon, 10 Feb 2014 12:03:20 -0600 On 02/10/2014 08:34 PM, Doug Crompton wrote: 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. 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. 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. Agreed. I am curious, though, what voltage is sent back to the USB buss from the device. 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... until, at least, I RF'ed the system again with HF signals from 75 and/or 40m.... ~sigh~ 73 = Best Regards, -Geoff/W5OMR _______________________________________________ App_rpt-users mailing list App_rpt-users@ohnosec.org http://ohnosec.org/cgi-bin/mailman/listinfo/app_rpt-users To unsubscribe from this list please visit http://ohnosec.org/cgi-bin/mailman/listinfo/app_rpt-users and scroll down to the bottom of the page. Enter your email address and press the "Unsubscribe or edit options button" You do not need a password to unsubscribe, you can do it via email confirmation. If you have trouble unsubscribing, please send a message to the list detailing the problem.
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. Chuck On Tue, Feb 11, 2014 at 4:26 PM, Ken <ke2n@cs.com> wrote:
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.
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.
73 Ken Attached Message From: Geoff <ars.w5omr@gmail.com> To: app_rpt-users@ohnosec.org Subject: Re: [App_rpt-users] Loosing TX Date: Mon, 10 Feb 2014 12:03:20 -0600
On 02/10/2014 08:34 PM, Doug Crompton wrote:
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.
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.
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.
Agreed.
I am curious, though, what voltage is sent back to the USB buss from the device. 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...
until, at least, I RF'ed the system again with HF signals from 75 and/or 40m.... ~sigh~
73 = Best Regards, -Geoff/W5OMR
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participants (3)
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Chuck Henderson -
Doug Crompton -
Ken