[Top] [All Lists]

Re: [RFI] Keyboard

To: rfi@contesting.com
Subject: Re: [RFI] Keyboard
From: "Roger (K8RI)" <k8ri@rogerhalstead.com>
Date: Mon, 5 Mar 2018 03:58:45 -0500
List-post: <mailto:rfi@contesting.com>
Fix RF getting into the kbd, BUT this is only a problem in the one configuration! If so, then the problem should not be the kbd, nor should there be a need to go through RF chokes and any other cure at, to, or on the kbd. As this happens in only one configuration the problem HAS to be from something different in this one configuration.  Your later work has pretty much proven this to be the case with the reconfiguration of the cabling using the SB220 hookup.

Therefore, look carefully at what is different.  Remember, all coax lines to the amp provide grounds. Not earth grounds, but ground paths between equipment units. network grounds, keying lines, coax shield lengths, common ground lengths between driver and final, different lengths to "earth (CPG)" compared to grounding between equipment grounds while being careful to differentiate between grounds between equipment and earth grounds (CPG) connections.  Changing comparable lengths can and often does create different voltages between pieces of equipment.  With the kbd we are looking at small voltages that can be created by changes of only a few inches, let alone, feet.

So the key question becomes, what is, or was different in the equipment intersections that could have caused this. For me, the problem going away would not be enough.  I'd be forced to find the answer as to what had been causing the problem.  Trying to fix the symptoms is like treating a cold. You never cure it, you just make yourself feel better while you have it.  In the case of the kbd interference, you should be able to discover what was causing the problem.

As I've mentioned a number of times, I have never needed to go through adding chokes in the equipment lines, or wiring.  I did need to add a second common mode choke in the feedline to the center fed 75 meter, half wave sloping dipole as a single choke wasn't enough, but I was fixing the source, not treating the symptoms.

73, Roger (K8RI )

On 3/3/2018 Saturday 10:47 AM, GaryK9GS wrote:
A better idea would be to fix the RF getting into the keyboard in the first 
place.  That's not normal.
What kind of antenna are you using?  Does this happen on only some bands?  At 
any power level.

Gary K9GS
-------- Original message --------From: dalej <dj2001x@comcast.net> Date: 3/3/18  
9:32 AM  (GMT-06:00) To: Joe <nss@mwt.net> Cc: rfi@contesting.com Subject: Re: [RFI] 
I’d use a #31 mix snap-on and wrap several turns though it.  I purchase mine from 
Mouser.  I don’t have the PN handy but if you need it let me know.

Those from RS I don’t count on to do a good enough job.

Dale, K9VUJ

On 03, Mar 2018, at 9:24, Joe <nss@mwt.net> wrote:

Is RF getting into a keyboard issue OK here, it is RFI in a way..

OK, Say you get RF into a USB keyboard. It just stops working and the only way 
to get it working again is a total re-boot.

I'm assuming the best option is ferrite beads on the cable.

Now question, where is the best placement of the beads. Keyboard end? Computer 
end?  BOTH?

I have two here, a small one where I could get one or two passes through the 
hole. ( it is a Radio Shack split thing )

and then a much larger one, also split,, but the hole is close to a inch ID. so 
I could do many turns.

What would be best to put where?


Roger (K8RI)

This email has been checked for viruses by Avast antivirus software.

RFI mailing list
<Prev in Thread] Current Thread [Next in Thread>