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Ge0rge
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  #2879208 4-Mar-2022 18:53
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Tried any model hobby shops?
I found this searching for copper rod. https://www.mitre10.co.nz/shop/k-s-metal-round-copper-rod-4-pack-1/16-and-3/32-inches/p/306417

Another option might be a welding supply store - copper brazing/filler rod.

Edit - bugger, just re-read the title and you want insulated. Jaycar sell heat shrink, wouldn't take too long to form it then put the heat shrink on.



RUKI
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  #2879217 4-Mar-2022 19:40
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Just try any electrician.
Last time I was looking for solid copper wires, one electrician gave me 5mm diameter off-cuts - those were 80mm long, insulated in obvious yellow/green "earth" color. 5mm was a external diameter of the copper, not the total diameter.

P.S. to avoid confusion by sales people, when asking them for, e.g. 1.5mm it has to be specified. either asking for a diameter or "mm squared" as these are obviously different measurements. E.g. 4mm diameter wire is 12.56 sq.mm




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neb

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  #2879244 4-Mar-2022 21:34
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Yeah, that's the annoying thing, I'm sure I had an ancient length of that hanging around somewhere and then used it for something where I needed its physical rather than electrical properties.



  #2879407 5-Mar-2022 12:31
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That sounds like 6mm^2 earth wire, but it's still 99% of the time a 7-strand single core.

 

 

NZ codes have a number of codes that require electrical wire to be stranded in certain situations, such as if installed in a caravan or on a catenary system, so most cable manufactured is stranded.

richms
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  #2879410 5-Mar-2022 12:44
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Try the scrap place opposite bunnings in wairau.





Richard rich.ms

  #2879474 5-Mar-2022 17:33
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Just be aware that the insulation on insulated wire probably won't be UV stabilized and if exposed to the sun will eventually crack. You would be better off using UV stabilized heat shrink.

neb

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  #2879515 5-Mar-2022 22:26
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Oh, it'll be inside a 25mm PVC pipe to protect the associated LNA, so it'll never be exposed to weather, it's purely to protect against surface corrosion. Thanks for all the advice, I'll try the transformer winding place first which seems to be the best bet, then scrap metal places.

 
 
 

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elpenguino
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  #2880171 7-Mar-2022 12:05
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neb:
elpenguino:

 

I see there's already a sensor in the Auckland area, are you planning to use your sensor there too?

 

For the network's benefit, your new sensor would ideally be elsewhere e.g. South Island.

 

I see a sensor in Tauranga is currently detecting activity to the NW when the Auckland sensor does not - which shows you these sensors work much better in low RFI environments.

 

Yeah, it's in Auckland, but in a reasonably low-RFI area, it's only been up for a day or two but I'm getting some pretty good low-noise readings with a few occasional spikes. However I don't have the correct E-field sensor setup yet, it's just 20AWG strung up in a side-building, not solid-core copper located further out from the house. For the H-field, the ferrites are on their way from Mouser so I expect to have them wound and up within the next week. There's also a bunch of other considerations like powering it from a low-noise linear power supply, there's a 5V switchmode that seems to be popular with other people running feeds that can't be good for the signal quality, and in the forums you can see posts of waveforms from CFLs and other noise sources which are entirely absent here. So it's not just location it's also how carefully you set everything up.

 

If you really want to optimise performance, install / run the sensor outside adjacent to the aerials and feed it with DC from indoors. The type of PSU is then irrelevant with appropriate smoothing and filtering and the lowest RF loss will occur.

 

What are you planning to do for your signal ground? 

 

What are you tallest structures outside and how far can you get away from them?





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  #2880482 7-Mar-2022 16:58
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elpenguino:

If you really want to optimise performance, install / run the sensor outside adjacent to the aerials and feed it with DC from indoors. The type of PSU is then irrelevant with appropriate smoothing and filtering and the lowest RF loss will occur.

 

 

Already done that way, the LNA is at the end of the run of coax right next to the sensor, powered through the coax. The whole lot is, or will be when it's finished, towards the top of a large puriri tree which is as far as practical from the house, is in a reasonably quiet area according to a scan of the property with a spectrum analyzer, and meets the aesthetics requirements for being pretty much invisible.

MadEngineer
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  #2880540 7-Mar-2022 17:44
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neb: This is ridiculous. Look at this listing from Bunnings, for example:

Nexas 2.5mm x 100m V90 Green/Yellow Conduit Cable

Conduit wire 2.5mm² single core
Suitable for fixed wiring of domestic and commercial circuits
Stranded copper conductors


And all of the "single core" or "solid core" cables are like this. Any sparkies able to comment on why, in NZ, stranded cable is regularly advertised as single core or solid core when it isn't?


Cable in the industry is described as for example 10mm 3c+e which is three core plus earth. Core does not mean non stranded. Where are you seeing solid as stranded?




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  #2880609 7-Mar-2022 19:13
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Yup, single core means it is electrically a single core. One set of copper conductor, surrounded by insulator. Electricity doesn't care (for the most part) whether that copper is in one, three, seven, 19, or 200+ strands. The ease of installation and long term reliability, however, favour more strands. There are several situations where cables have a minimum strand count but I can't think of any with a maximum.

 

 

 

Is 1mm^2 really going to be too small? It sounds like negligible current will be passing through it.


wally22
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  #2880732 7-Mar-2022 20:22
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What exact level of insulation is required? My neighbour rewinds magnetos, coils, welders and transformers so I could ask him tomorrow. Best to know specifically as he will ask. If it is not specific then more likely to have some. Shellac?

 

Is 1.5mm preferable to 4mm or the reverse?


neb

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  #2880746 7-Mar-2022 21:32
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SomeoneSomewhere:

Yup, single core means it is electrically a single core. One set of copper conductor, surrounded by insulator. Electricity doesn't care (for the most part) whether that copper is in one, three, seven, 19, or 200+ strands.

 

 

The difference in this case is that it's not a conductor, it's one side of a capacitor with the earth as the other side. The vertical orientation is to catch cloud-to-ground (CG) strikes, the most common type. It does less well on IC (intra-cloud) strikes.

 

 

Edited to add: So don't think of it as an antenna, think of it as a probe.

 

 

The reason why it needs to be a single solid mass of copper is that a stranded cable would make for a rather erratic capacitor plate with the charge unevenly distributed across the strands.

 

 

Thanks for the offer wally22, went and picked some up today from the place suggested by Rust.

  #2880750 7-Mar-2022 21:45
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The strands are all in constant contact with each other and behave as one conductor in most cases, including when operating as a capacitor plate. I'd be very curious to see a test on if there was any actual difference between them (I might look into setting a pair up in Wellington?).

 

Litz wire would be a different story, but we're not talking about that.

 

That said, you're well outside the realm of what electrical cable is generally specified and used for. Even with VSD cable (where high frequency performance and capacitance is fairly important, including sometimes having three ground wires so that no phase has more capacitance to ground), I haven't seen any distinction between stranded and finely stranded/flexible. Solid is not generally available.


neb

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  #2880755 7-Mar-2022 22:05
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SomeoneSomewhere:

The strands are all in constant contact with each other and behave as one conductor in most cases, including when operating as a capacitor plate. I'd be very curious to see a test on if there was any actual difference between them (I might look into setting a pair up in Wellington?).

 

 

So would I :-). The exact details of this are outside my area of expertise so I just went with the solid conductor because multiple sources specify this.

 

 

Another issue is that they've had problems in the past with people setting up systems in a somewhat erratic manner (this really isn't a plug-and-play setup) and getting not-so-good data submitted, so I want to try and do it by the book as much as possible.

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