K3 RFI in transmitted audio

[David Herring-3]

Yes please do post back here the final outcome. While not strictly an Elecraft issue, it is one of interest.

Specifically, I'd like to know how one would properly bond equipment (I guess for DC and audio purposes) AND RF ground the same equipment at the same time.

Thanks and 73,
Dave
AH6TD

Sent from my iPhone

On Sep 13, 2010, at 7:13 AM, "Eric Swartz - WA6HHQ, Elecraft" <[hidden email]> wrote:

>  Jim, Don and Joe,
>
> To keep list traffic reasonable, let's take this recurring discussion
> off list to direct email for now. Once you have all agreed please feel
> free post the results to the list.
>
> Also, there is a lot of past info on this topic that is searchable in
> the list archives.
>
> Also, please keep all discussions civil on, or off, list.
>
> 73,
> Eric  WA6HHQ
> Elecraft List Moderator
> -----
>
>
>
>
>
> On 9/13/2010 9:08 AM, Jim Brown wrote:
>> On Mon, 13 Sep 2010 09:40:00 -0400, Don Wilhelm wrote:
>>
>>> If we were discussing RF, then your single point ground connected to a
>>> low impedance ground for RF would be correct - keep the path to RF
>>> Ground the same distance for each piece of equipment. will achieve
>> what
>>> is needed for lightning protection.
>> I disagree with that concept as well. The notion that a separate wire
>> is required for each piece of gear to a point that is often at a fair
>> distance from a closely arranged collection of gear in a typical ham
>> shack when that gear is already well bonded together does not make
>> sense. How, for example, do we insure that each wire is the same
>> length, follows the same or a similar path, and thus has the same
>> inductance?
>>
>> There is NO CONFLICT between bonding all equipment chassis together by
>> the shortest practical path, as I've outlined, and making one or more
>> bonds between that equipment and the earth electrode system (ground
>> rods).
>>
>> Indeed, both IEEE Standards on Grounding and most building codes either
>> recommend or require multiple paths to ground for lightning protection.
>> A large part of the thinking behind that is that the inductance is
>> reduced by having multiple wires in parallel.
>>
>> As hams, we tend to think of our antennas as the only source of
>> lightning ingress to our homes, but that is FAR from reality. It's like
>> looking at the circus elephant through a tiny hole in the tent. EVERY
>> CONDUCTOR that enters the house, and every conductor INSIDE the house,
>> is a receiver for energy from lightning. That's why IEEE Standards and
>> nearly all building codes call for ALL non-powered metal to be bonded
>> together, and to one or more earth connections, and for all earth
>> connections to be bonded togther.
>>
>> One other thought on this. In thinking about how all this fuzzy
>> thinking about so-called single point grounding came about, one source
>> of it might be equipment with a pin 1 problem. If, for example, the
>> bonds to the equipment are improperly made to some point OTHER THAN THE
>> CHASSIS, then yes, lightning current WOULD go through equipment if it
>> was daisy-chained. But that's not a GROUNDING problem, it's an
>> EQUIPMENT problem, and it's IMPROPER bonding.
>>
>> The good news is that I don't recall ever seeing ANTENNA connections in
>> ham gear with pin 1 problems (except, perhaps, for an occasional RX
>> antenna). It's only the audio and control wiring, and an occasional IF
>> output.
>>
>> 73, Jim Brown K9YC
>>
>>
>>
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[ab2tc]

Hi all,

Just for the record, here is what I am doing for "grounding" and "bonding". Outside the shack I have all coaxes coming to an entry point near a basement window where they go through. The coax shields there are all connected to a 8' grond rod near the entry point. This ground rod is also bonded to the AC utility entry box which is nearby. So far I think I am legal. Inside there is nothing "bonding" equipment together except the 3rd wire on the power cords to the various equipments. The K3 has isolated audio connections so that's not a problem. My most recent change is to get rid of my USB to serial adapter and instead use a serial to Ethernet adapter computer connection. I do not have a serious problem with birdies from my computer system. I do have some birdies from my network but they are definitely picked up by my antenna(s) and not by improper shielding and grounding. Am I doing anything wrong here?

BTW my MFJ 4125 power supply definitely has the V- connected to the chassis and the AC plug ground, but it doesn't seem to be a big problem. I have looked inside and it doesn't look like it's easy to fix.

AB2TC - Knut

 for my

David Herring-3 wrote

Yes please do post back here the final outcome. While not strictly an Elecraft issue, it is one of interest.

Specifically, I'd like to know how one would properly bond equipment (I guess for DC and audio purposes) AND RF ground the same equipment at the same time.

Thanks and 73,
Dave
AH6TD

Sent from my iPhone

<snip>

[Jim Brown-10]

On Mon, 13 Sep 2010 13:13:53 -1000, David Herring wrote:

>I'd like to know how one would properly bond equipment (I guess for DC and
>audio purposes) AND RF ground the same equipment at the same time.

Study my posts. That's the right way to do it, and that's why I spent the
time going through it.

73, Jim K9YC


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