Author Topic: H Field wiring  (Read 1899 times)

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Offline 92merc

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H Field wiring
« on: April 11, 2016, 11:42:28 AM »
On my H field, I have some noise on Channel B I pick up compared to my Channel A.  My H Field is mounted to the ceiling of my garage and is shielded.  But it is also about 8 feet above my electrical panel in the garage.  So I suspect I might either be picking up noise from the panel, or from the house.  Either way, it would be best to move the antennas outside.  I'm using the ferrite core ones BTW.

So my plan is to leave the H field controller mounted to the ceiling, but move the antenna's outside into a PVC until I'll build.  I'll keep it shielded and that shield grounded.  But the big question is what wiring should I use to connect the antennas to the H Field controller.  I don't think I can move the controller to the attic of the garage because that probably is 120-130 degrees in the summer.

I don't want to use any CAT wiring because that'll be twisted pairs.  And at 20 feet or so, I'm guessing that'll add or subtract from the the antenna's coils.  But can I use un-shielded phone wire?  Should I be using shielded cable?

I'm not positive this will clean up my channel B issue for sure.  But given my current location, I think that is probably the best next step.
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Offline miraculon

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Re: H Field wiring
« Reply #1 on: April 11, 2016, 04:25:57 PM »
On my H field, I have some noise on Channel B I pick up compared to my Channel A.  My H Field is mounted to the ceiling of my garage and is shielded.  But it is also about 8 feet above my electrical panel in the garage.  So I suspect I might either be picking up noise from the panel, or from the house.  Either way, it would be best to move the antennas outside.  I'm using the ferrite core ones BTW.

So my plan is to leave the H field controller mounted to the ceiling, but move the antenna's outside into a PVC until I'll build.  I'll keep it shielded and that shield grounded.  But the big question is what wiring should I use to connect the antennas to the H Field controller.  I don't think I can move the controller to the attic of the garage because that probably is 120-130 degrees in the summer.

I don't want to use any CAT wiring because that'll be twisted pairs.  And at 20 feet or so, I'm guessing that'll add or subtract from the the antenna's coils.  But can I use un-shielded phone wire?  Should I be using shielded cable?

I'm not positive this will clean up my channel B issue for sure.  But given my current location, I think that is probably the best next step.

I am a little confused by this statement:

Quote
So my plan is to leave the H field controller mounted to the ceiling, but move the antenna's outside

Do you mean amplifier?

Making this assumption, as I recall the leads from the antenna coils must be kept short. Adding wire between the ferrite antennas and the amplifiers will add capacitance that will affect the signal. I recall warnings against twisting the wires as well and as you noted.

I would try to come up with a weatherproof enclosure for the amplifier/antenna assembly and remote the whole works.

I also have my antenna/amps out in the garage. I was able to find a fairly quiet area for the old "Green" unit on the side of the wall opposite of my controller housing. The 1 meter loops for RED are up in the rafters and there wasn't much latitude for movement with them. I re-routed some AC wiring to get it further away from the loops. The proximity to the AC wiring was only a problem when it was a few inches away from the antenna loops. Once I moved them to about 6+ feet away, there was no problem.

The harmonics from the power itself is low enough that the HPF in the amplifier board should take care of it. Do you have some noisy device out there contaminating the power lines? Dimmers, heater controllers, etc? I had a space heater with a variable speed control that I had to return to the store because it raised havoc with both detectors. I used the excuse that it affected AM radio (it did).

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Offline 92merc

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Re: H Field wiring
« Reply #2 on: April 11, 2016, 04:40:16 PM »
Yes, sorry, amplifier.

So your controller is in the attic?  My attic is insulated, but accessible.  The only electrical wiring that I would have to avoid is the two power outlets for the garage opener.  But I have some CAT 6 shield yet left over, so I could do that.  Still have the amp near the antennas, but put them up in the attic and farther away from the electrical panel.

I do know I have one dimmer light in the dining room that messes with the E Field, but I haven't found anything in particular that is causing my H Field issues.  Since it is one channel and fairly consistent, I'm guessing it's one source.  I suspect it's actually not in the house even.  I've turned off a bunch of the circuits in my house trying to track it down and can't.  Not all circuits, but most.  So that's why I'm hoping to move the H Field portion to a quieter part of the garage.
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Offline W3DRM

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Re: H Field wiring
« Reply #3 on: April 11, 2016, 04:44:01 PM »
Greg is correct - the ferrite antenna MUST BE connected with leads to the amplifier as short as possible. Excess length and/or twisting of the leads will result is less than a satisfactory outcome.

First of all, since you seem to only be having problems with Channel B, I would suggest some troubleshooting is in order. Here are a few things you should try before you go to the trouble of physically moving your equipment.

  • Switch the ferrite antenna leads from one amp input to the other. If the problem is noise being picked-up by the "B" ferrites then the noise should move to the Channel A. If it does move, go on to step # 2 below. If not, then you need to go over your amplifier board to make certain you don't have any bad solder joints or bad connections on it.
  • Try rotating your ferrite antenna assembly to see if you can get a null for the interfering signals. You may find such a position that allows you to operate without having to move anything but the ferrites themselves.
  • If the rotation doesn't solve your problem, you will have to move both the ferrites and the amplifier board to another location. That location can only be found by moving the entire assembly around your home until you find the "sweet spot" for low noise. I wouldn't worry too much about heat issues with the H amplifier. I have mine in a fully-enclosed shelter I built for both my H and E field amps. It sits outside in direct desert sun and I've never had any issue related to heat (or cold, in the winter). Those boards and their components are pretty tough.
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Offline 92merc

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Re: H Field wiring
« Reply #4 on: April 11, 2016, 04:45:06 PM »
Now that you mention a box, I might have a better idea I'll have to think about.  I do have a left over electrical box that is weather proof that might fit the controller.  I might be able to move that outside, then attach the antenna system outside as well.

That corner of the back of my garage would also have the added effect of some shielding by the way of metal soffits.  Those should help shield noise from the garage panel below.

That should be some food for thought.  I'll see what I can come up with.
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Offline 92merc

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Re: H Field wiring
« Reply #5 on: April 11, 2016, 04:48:00 PM »
I can switch channels easily to verify that.  But I have my antenna's mounted inside of shielded tubes that are zip tied to a peg board.  That whole assembly is mounted to the ceiling.  So rotating wouldn't be easy.  I'd probably have to rotate the whole pegboard.

But I can at least test the swapping of channels tonight when I get home.
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Offline W3DRM

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Re: H Field wiring
« Reply #6 on: April 11, 2016, 04:53:33 PM »
I can switch channels easily to verify that.  But I have my antenna's mounted inside of shielded tubes that are zip tied to a peg board.  That whole assembly is mounted to the ceiling.  So rotating wouldn't be easy.  I'd probably have to rotate the whole pegboard.

But I can at least test the swapping of channels tonight when I get home.

Try the lead swap first and then simply rotate the entire pegboard to see what happens, if anything. I'm assuming your H-field amp is also mounted on the pegboard, correct?

My outside housing is completely sealed. I have no ventilation in it at all and don't have any heat problems. I suspect internal summer temps are well over 120 or so degrees F.

Just thought of something - are you using shielded cat-5/6 wiring and connectors?
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Offline miraculon

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Re: H Field wiring
« Reply #7 on: April 11, 2016, 04:55:01 PM »
Amp is connected to the bottom of the loop antennas, the controller is in a wall-mounted cabinet.

See the picture:



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Offline 92merc

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Re: H Field wiring
« Reply #8 on: April 11, 2016, 05:06:16 PM »
I'm using all CAT6 shielded.  Controller to both amps.  I've shielded the crap out of system from the get go.

After the antenna swap, I probably could rotate the  H Field assembly 90 degrees without too much issue.

Here is the H Field as it's mounted to my pegboard.  E Field and Controller and below mounted to the wall.
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Offline 92merc

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Re: H Field wiring
« Reply #9 on: April 11, 2016, 05:08:37 PM »
I should add, the antenna tubes no longer look like that.  I too off the middle part of the T.  It's just the tubes zip tied to the pegboard.  Then the leads come out and into the amp.  No CAT cable in between anymore.

I did that when I wound up a new longer antenna.  Just haven't updated my pictures in my documentation.
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Offline 92merc

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Re: H Field wiring
« Reply #10 on: April 13, 2016, 10:13:19 AM »
I did my channel switch yesterday.  I have my controller reboot every night at midnight.  Looking at the triggers of the H channel, now my A channel is going over the threshold about twice the times my B channel does.  Which matches what I saw before on Channel B.  So it isn't the amp.

This weekend, I'll crawl up there again and see what effect rotating my board does.
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