Author Topic: H-Field Query?  (Read 469 times)

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Offline Phil23

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H-Field Query?
« on: September 03, 2019, 10:06:17 PM »
Hi All,

I've got all my stuff sitting in the yard at the moment in preparation for relocation to the back shed.
Interference on the E-Field & one of the H-Fields has dropped heaps now it's away from the Solar.

Just after feed back on my H-Fields though.
It's a Mobius Loop, 600mm in diameter with 4 turns of Coax.

The Coax ends connecting to the Amp are....., well not quite tidied up yet (after 2 years).
Still deciding how I might change it a bit; maybe remake the pole in 100mm instead of 65mm PVC etc.

Are those loops likely to be catching much significant interference, or degrading the performance much?
(IE, should I get to it now, or another 12 months down the track).

If the answer is "Big Difference", I might do it this week-end.

Cheers.

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For Reference, I think that J-Box is about 100-120mm.

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« Last Edit: September 04, 2019, 03:02:53 AM by Phil23 »

Offline Phil23

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Re: H-Field Query?
« Reply #1 on: September 04, 2019, 07:14:05 PM »
Reason I'm hesitating to change it immediately is that I've been considering rebuilding it in 100mm PVC with an inspection T to house the amplifier.

Something like this....

First issue I see though is water coming down the pipe & getting to the amp.

So maybe I'd need to forget the screw on cap & cut the existing square box into the T & then seal that.

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« Last Edit: September 04, 2019, 07:16:18 PM by Phil23 »

Offline Phil23

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Re: H-Field Query?
« Reply #2 on: September 06, 2019, 05:51:11 PM »
No Comments?

Can I suggest a few?

1. Probably wouldn't change the performance much, if any...

2. Mate; It's a bit rough & you should really finish it off properly You may find it performs a whole lot better...

Figured I can sink the 105mm square junction box into the 100mm PVC T & get shorter terminations into that.

Other thing for consideration is adding transformers.
I did get the correct toroids about 12 months back & wound a couple,
but haven't actually got to try them.

Other stuff got in the way.

At any rate wanted to be adding them in such a way that I could easily take them back out if I didn't get an improved result.

Bit hard to remember why I chose a Mobius Loop.




Offline DaleReid

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Re: H-Field Query?
« Reply #3 on: September 06, 2019, 10:20:59 PM »
I can say from experience with my RED amp that water is the last thing you want it to be around.  Make sure that there is no way in from the antenna leads and connections.  EVER.

I'm running an E-probe only RED setup now because of this.

Sad day, but what does one do?  And I 'thought' I had the whole thing sealed up pretty well.  Guess I was wrong.  Don't risk your amp.
Dale
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Offline Cutty Sark Sailor

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Re: H-Field Query?
« Reply #4 on: September 07, 2019, 08:16:28 AM »
Remember, the H fields DO NOT need to be exposed to elements... they will work fine in a basement or attic, or anywhere there is a quiet EM environment, and no magnetic walls or structure to interfer.
The E Probe to be best effective MUST be outside, no connection to ground... away from metal... height above ground seems to be important, at least a couple of meters, away from any buildings, noise, other structures, HVAC etc... it functions as a probe sensitive to charge content in air, and is very sensitive.

One of the best things a person can do with any of the Outdoor installs would be to disassemble periodically, and check for moisture, etc Like Dale, many of us have learned that lesson, especially with connecdtors... Folks in 'salty' environments face a real challenge..

If air can get in.. so can moisture.  Nothing beats a bit of Preventive maintenance, since I cannot guarantee my ability construct a hermestically sealed enclosure... heh...
« Last Edit: September 07, 2019, 08:18:24 AM by Cutty Sark Sailor »
 

Offline DaleReid

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Re: H-Field Query?
« Reply #5 on: September 07, 2019, 08:48:03 AM »
Indeed.  The Blue Hfield I have is in a more protected, but quieter, enclosure, and the ferrites and the amp are inside a big plastic box that keeps dust and direct moisture off.  So far so good.  And I am a firm believer in a tiny bit of dielectric grease for the connections, but of course does nothing to protect the board.

My first encounter with the green crud was with a Boltek active antenna which stopped working.  I saw the current that the unit drew had caused some green stuff to accumulate on the RJ45 and a long session with a dental tool (thanks, doc, for sharing the ones you were going to toss) I got it off, no extra damage to the pins and back to working again. 

One thing that puts a high level of care and protection in my mind is the enormous demand for the kits and that so far there haven't been any easy sources for just a part of the kit, like an amp if one gets zapped or damaged. 

I know my shed which is a luxury for some, isn't heated and remote enough that the neighbors and my house noise is a bit back.  Even in there some things like cardboard boxes seem to get damp in the spring and fall (not wet, but not like house stored stuff) and I have wondered about buying a bunch of dessicant and putting it in the plastic box to try to keep the humidity down in side it.

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