[Elecraft] 160m loop experiment a big failure

[Guy Olinger K2AV]

Normally, the field of an antennas diminishes as one goes toward the shack
and (usually) away from the antenna.  Your situation makes every conductor
in your shack (and your house) *heavily* coupled.  If you want a fight to
the death on making a station work in a heavy RF field, you will probably
emerge as an expert in your field sometime in the future, as the reality of
making that happen in such an extreme situation will tolerate no
half-solutions, no old wive's fixes, and no electronic myths, no
ham-reflector tales.  *And* you will have to plug *every* hole on the way
there.  Maybe taking K9YC's stuff to another level...   He would enjoy
working with you on that.

Your experience, if successful, in the end would make a useful and very good
book.

There are *easier* ways to get a signal on 160   :>)

>From back in my AT&T days, and telco offices in the main field of 50K
broadcast stations, there are a lot of very counter-intuitive things we had
to do in the office I was involved with.  In some cases using frame "ground"
as "ground" made things a lot worse.  "Dirt" certainly was no savior there.
 Each equipment bay had to be evaluated on a case by case basis, and the
negative power leads had to be balanced with positive and UN-grounded
negative bypassed to each other to keep from rectifying RF in the power feed
circuitry.

I suspect there were some Bell Labs guys who came away with brain damage on
that project.  "What NOW?" was the word of the day.

73, Guy.

On Sat, Oct 15, 2011 at 12:14 PM, <goldtr8 at charter.net> wrote:

> I set up a 160m loop in the yard to try one out from all the great
> reading I did regarding the antenna.
>
> For me I can get it to tune with no problems except the RF in the shack
> is terrible.
>
> I ran 450 ohm ladder line from the antenna to my balanced line
> connections on my MFJ 962 d tuner.
>
> As soon as I connect the ladder line the RF is bad, basically everyone
> states that I sound like I am in a jet airplane.
>
> Now there is also a bit more to the story as the loop surrounds the
> house as that is how the trees are plus the dipole is also very close to
> one of the edges on the inside of the loop.
>
> So I dont know if the problem is that everything is in the middle of the
> loop, or running ladder line into the shack is a bad thing, maybe the
> tuner internal balun is not the correct one.
>
> Bottom line is the K3 was real unhappy with this scenario so the ladder
> line is pulled out of the shack and coiled up on the tree next to the
> loop outside.
>
> One thing I have researched this morning is that I need a current balun
> and I should have it external to the shack and run coax between it and
> the shack.  Also I should have the shield grounded like I do with the
> dipole to direct ground.
>
> So I thought I would share my current failure while I ponder my next
> move or give up on the loop.   Ok I wont give up, YET!
>
> Cheers
>
> ~73
> Don
> KD8NNU
>
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