[Elecraft] Update on my progress - Now General RF Issue WAS 160m loop experiment a big failure

[Guy Olinger K2AV]

I have been watching this thread out of the corner of my eye, but not
reading it real close.  This post caught my attention.

I'm thinking you may actually have a break in the shield at a
connector point on the coax.  That would cause heavy RF on the coax
shield coming back at the shack, and would STILL accept power from
your transmitter. Putting the coax on the ground may relieve stress on
the joint and allow the shield to make contact again.

Sometimes folks forget to solder the shield to PL259 as just one way
this can happen, or the shield internally isn't trimmed right for the
connector, etc, etc, ad naseum.

Another way that kind of break can happen is a lightning strike that
evaporated the connection at the connector, or at a strike point.

But to my mind, anyway, the coax shield and/or connections are
completely suspect for shield continuity.  What you have described are
what would cause me to completely replace the coax and connectors.

We spend so much money on rigs and amps and then go cheep cheap on
feedline and connectors.  Consider small hardline and connectors made
for that hardline, and some kinds of troubles will just go away.

73, Guy.

On Sun, Oct 23, 2011 at 9:13 AM,  <goldtr8 at charter.net> wrote:
> First, let me say thank you to everyone on the list who has replied via
> the list or directly.   The help has been fantastic and has increased my
> general knowledge as well as helping me with the problem.
>
> Althought I have pointed to the start of the problem with the
> installation of the Loop and the install of the propane tank and
> possible crushed coax, I now believe that I have always had some RF
> issues but it was brought to my attention by the Loop being real bad and
> then I was highly sensitive to the whole system.
>
> First I had made a significant error in the basic grounding of my shack.
> This error I will call the green wire mistake.  What I had done was add
> the chassis ground of all my 12v devices  and tuner to the green wire
> ground of the house electrical system.  This is in fact a signficant
> error and has been corrected.  What I have learned that there is a
> difference for a saftey ground for lightening protection and so on and
> it has nothing to do with an RF ground.  So green wire error fixed, long
> term a total revamp of the system for a safety ground.
>
> Second I did a lot of checking of the coax yesterday.  Checked it with
> nothing attached, checked it with a dummy load, used functions of my MFJ
> 259b that I did not even know existed.  Basically the coax checks out
> fine, but I still have RF.   The coax at this point in time is no longer
> buried, I completely unearthed it.
>
> At this point in time I put a choke at the antenna feed up in the air
> with 31 mix ferrites and no improvement.  So if the problem is at the
> antenna feed this should have fixed it.  I remove my lightening arrestor
> from the system just to check it out no change.  So I pull the choke
> down.
>
> Next I put a choke right at the antenna out the same choke that I had
> put on the antenna feed point.  Wow big improvement plus I added more
> snap on 31 ferrites directly on the coax.   So I have a choke in the
> shack and now I can go full power.   So having the choke at the feed
> into the antenna tuner has a dramatic effect.
>
> Now I am thinking ok I will burry the coax again, easy to do in the soft
> grass plus I want to see if the problem turns on again as I have changed
> the system with the coax laying on the ground and the outside is dry not
> directly coupled to the set ground.  After the burry RF is bad real bad.
> So coax is now on laying on the ground again unearthed and the system
> again functions, points again to bad coax.
>
> I am now convenced that this is it so I turn on the shack PC to get some
> more information and so on.  Plus I am talking to some other hams on
> what I have found.  As the PC boots up the RF is back and it is strong.
> Holy Sxxt Batman, now what.   So I ponder this for a moment, since I
> removed my geen wire error the PC is no longer connected to the K3 than
> thru the rs232 so I am assuming Pin1 problem.  I make a ground wire from
> the chassis of the PC to the center of the grounding point (grounding
> star as it is referred to) and fixed.  So I take a critical look at the
> PC installation and the coax runs right next to the PC.  So I disconnect
> everything and move the PC to the other side of the desk to get it as
> far away from the coax as I can plus this eleminates short jumper cables
> for the mouse and so on.  So other than a brief instant when the PC
> boots up and it is a very specfic part of the boot cycle there is no RF.
>
> So in a nutshell
>
> 1) fixed green wire problem
> 2) unearthed coax and it is laying on the ground on the top of the grass
> 3) build choke with 31 mix at antenna out on the tuner
> 4) moved PC
>
> I am on the air.
>
> To do when the order shows up from UPS.
>
> Install new coax, I assume the one I have is not happy anymore and test
> the system to see if I can remove the choke at the tuner.
>
>  From my perspective I am on the air, but I do not have a robust
> installation being on the 2nd floor.  I probally can survive this winter
> this way with the simple antenna shield grounding outside as I did last
> winter as there is no lightning normally.  However, I have to determine
> the best way to redo the installation and am considering moving the
> shack to the basement where then it will be signficantly eaiser to have
> the shack properly grounded for safety and then bonded.
>
> Again thanks for the help, as I am on the air but not convinced that I
> have it fully cured.  So there may be more questions in the future when
> I find stuff starts to not work again.
>
> ~73
> Don
> KD8NNU
>
>
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