I too had several RFI as well as "common ground" problems when using the
microHAM Digkeyer. Joe (along with others) suggested the use of ferrite
chokes and/or torrids to minimize or eliminate RFI. I purchased several type
from amidon corp. http://www.amidoncorp.com/pricing/ who provided expert
help as well as great service. One torrid on each end of the usb cable
eliminated my problem but I continued to experiment as to the original
source. As it turned out, it was the mouse and cable assembly that was
creating the RFI. Once I removed the mouse, the RFI went away and I could
even remove the torrids.
Dan
----- Original Message -----
From: "Joe Subich, W4TV" <w4tv@subich.com>
To: "'Jim Brown'" <jim@audiosystemsgroup.com>; "'WriteLog Reflector'"
<writelog@contesting.com>
Sent: Monday, November 12, 2007 9:12 AM
Subject: Re: [WriteLog] RFI and Keyers
>
> Jim,
>
> To follow up on this one time ...
>
>> I've also seen a number of posts on the NCCC list from good
>> engineers who have fixed stability problems with Microham
>> products using ferrite chokes on interconnect wiring. That
>> fix would not work (or be necessary) if he was right.
>
> Others may have fixed alleged problems with "microHAM products"
> by adding ferrite chokes on the interconnect wiring but they
> are masking a problem that lies elsewhere much like an "antenna
> tuner" masks problems at the antenna by applying matching at the
> transmitter.
>
> The "Pin 1" issue is in the computer - specifically the USB
> port - and not the microHAM product. If you check most of
> the consumer computers these days you will find several red
> flags for Pin 1 problems. First, the USB connector shield is
> often not connected to the motherboard ground plane and not
> connected to the metal case of the computer (if the case is
> metal). In addition, the USB Power return (circuit ground)
> is not connected to the power supply "ground"/chassis. Finally,
> most amateurs do not ground their computers other than any
> chance grounds through common leads to their radio and/or
> the line "safety ground."
>
> The issues with both "radiated noise" related to USB and
> data loss in the presence of RF can be related directly
> to Pin 1 problems in the computer - laptops are more of a
> problem that old style metal case "tower" systems.
>
> The solution is multi-fold ... proper design of the computer
> motherboard AND chassis, proper grounding of the computer
> (a short strap to the station "common point ground") and
> eliminating common mode currents on cables coming into the
> shack (e.g., proper grounding of all cables to the common
> point ground at the entry window with common mode chokes
> between the entry window and equipment).
>
> 73,
>
> ... Joe Subich, W4TV
> microHAM America
> http://www.microHAM-USA.com
> http://groups.yahoo.com/group/microHAM
> support@microham.com
>
>
>
>
>
>
>> -----Original Message-----
>> From: writelog-bounces@contesting.com
>> [mailto:writelog-bounces@contesting.com] On Behalf Of Jim Brown
>> Sent: Thursday, November 08, 2007 11:08 AM
>> To: WriteLog Reflector
>> Subject: Re: [WriteLog] RFI and Keyers
>>
>>
>> On Tue, 6 Nov 2007 20:49:42 -0500, Joe Subich, W4TV wrote:
>>
>> >With respect, the microHAM products were done correctly with
>> >regard to any "pin 1 problem."
>>
>> While I respect Joe and his business, I believe that Joe is mistaken
>> about this. He and I are corresponding privately, and I've pointed
>> out some components of the RFI problem that others are seeing. I've
>> also seen a number of posts on the NCCC list from good engineers who
>> have fixed stability problems with Microham products using ferrite
>> chokes on interconnect wiring. That fix would not work (or be
>> necessary) if he was right.
>>
>> 73,
>>
>> Jim K9YC
>>
>>
>>
>>
>> _______________________________________________
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>> http://lists.contesting.com/mailman/listinfo/writelog
>> WriteLog on the web: http://www.writelog.com/
>>
>>
>
> _______________________________________________
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>
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