I'm not going to get into a huge debate about these issues because not everyone
is going to agree...but!
I think it important to differentiate these discussions between the two things
that are trying to be solved. In one case noise on transmitted audio and RF
entering the low level signal path is the primary discussion related to the
Eagle user.
The other is proper techniques for dissipation of lightning strike energy. The
lightning strike grounding discussion comes into play because 99 percent of the
grounding work attempted and brought up in the subsequent discussion is each
individuals work to protect their station from a static discharge or a
lightning strike event and not noise/RFI mitigation.
The techniques for resolution of the two are a good bit different and one does
not solve the other...
For example Jim is recommending basically daisy chaining bonds from chassis to
chassis then to a ground point. While that may be good technique for noise/RFI
and so called "pin1" mitigation, it's poor and un-recommended technique for
lightning potential dissipation. The recommended and industry standard
technique for lightning potential dissipation is to use a low impedance
connection of each chassis directly to the central point ground system. ( or a
heavy buss bar that is a low impedance extension of the central point ground)
You don't want to share the high strike potential that ended up on that chassis
with the chassis of every other device in the shack along the way before
hitting the ground point. You will notice I mention "Low Impedance" a lot.
That is one of the most important aspects of protection for lightning strike
events. Cable dress techniques have a lot to do with this as well...you can
use a 4/0 conductor but if you bend it in a sudden sharp 90 degree ang
le or create a loop with excess you have just created a high impedance path
and lightning strike energy will exit the cable to a lower impedance path.
(ie...depending on the third pin in your power cable to dissipate lightning
strike potential....it's a high impedance path for that energy and the ground
potential rise will be tremendous)
These discussions keep crossing the line back and forth between noise/RFI
mitigation technique and lightning protection technique and it is confusing to
many.
I would suggest keeping your high current grounding work as lightning potential
dissipation/protection and your pin 1, shield handling and low level signal
path RFI issues separate. They do interact to some degree but also need to
coexist. I would never eliminate the lightning protection grounding as a
method of resolution of the pin 1, noise/RFI to the low level signal path
problem because to do so would leave the door open inviting disaster.
Now back to your regularly scheduled programming...
Cecil
K5DL
> On May 15, 2014, at 3:49 PM, Robert <rmcgraw@blomand.net> wrote:
>
> All lightning protection must exist outside of the structure.
>
> Do nothing to invite lightning inside unless you desire a lot of damage.
>
> 73
> Bob K4TAX
>
>
>
> Sent from my iPhone
>
>> On May 15, 2014, at 3:39 PM, Brian Carling <bcarling@cfl.rr.com> wrote:
>>
>> AC 3rd pin is not going to be a very effective ground for protection from
>> lightning damage.
>>
>> Best regards - Bry Carling AF4K
>>
>>
>>
>>> On May 15, 2014, at 4:17 PM, Robert <rmcgraw@blomand.net> wrote:
>>>
>>> Braid is not the best choice for a low inductance RF path. It is although
>>> necessary for flexible applications.
>>>
>>> Personally I bond all equipment to the station supply and do not use
>>> anything but the AC 3rd pin for safety reasons.
>>>
>>> 73
>>> Bob, K4TAX
>>>
>>>
>>>
>>> Sent from my iPhone
>>>
>>>>> On May 15, 2014, at 2:20 PM, Carter <k8vt@ameritech.net> wrote:
>>>>>
>>>>> On 5/14/2014 5:56 PM, Stuart Rohre wrote:
>>>>> Some Yaecomwoods do suffer from RF entering the rig.
>>>>>
>>>>> MOST ANY rig will if you have a bad shield connection on coax jumper, or
>>>>> have rig too close to the antenna, (second floor shack), and there are
>>>>> many other rig and feedline issues to rule out in any RFI case.
>>>> True, can be many causes, but I am in a basement shack. Also, a few years
>>>> ago, I used a Drake TR-7 on SSB with everything else the same and it
>>>> worked fine. However, I realize that the TR-7 was not as "computerized"
>>>> (dependent on microprocessors) as the Omni VI.
>>>>>
>>>>> Rule of thumb: Power all equipment from same circuit breaker of the
>>>>> house. That ensures AC grounds will not be coming from widely different
>>>>> locations. IF you have to use a long ground wire for lightning
>>>>> protection ground on the station (like from second floor shack), consider
>>>>> that it could act as an "antenna" for pick up of RF from the real
>>>>> antenna. You may need tuned radials, or a radial for each favorite band.
>>>> Good tip and I believe I am on the same breaker for all the ham equipment.
>>>> Again, a basement shack and 5 or 6 feet of a single 3/4 inch wide braid
>>>> from the ground of each piece of equipment to the ground rod right on the
>>>> outside of the basement wall.
>>>>>
>>>>> You could always examine the quality of the grounding of the mike cable
>>>>> shield. Some older mike cords had just a multi-strand wire wrapped in
>>>>> one direction and not a hatch pattern wire shield. Some aluminum foil
>>>>> shields don't make a good low impedance connection by clamping.
>>>>> (Connections that can't be soldered are suspect).
>>>>
>>>> Should have mentioned this earlier, but back in the day before I used any
>>>> computer interface, I had the problem with both a TT 705(?) mic and a Heil
>>>> Pro headset. Probably unlikely that both were defective.
>>>>
>>>> 73,
>>>> Carter K8VT
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