Source of Aluminium Lined Plastic Water Pipe?

Once again if it is 15mm I doubt it has the aluminium barrier.

I think a trip to Wickes is called for. The pipe's spec on John Guest's website dosn't say what the barrier is made of, just that it's blue. Could be anodised aluminium or perhaps a different type of plastic. Wickes stock a different make that might be aluminium: again the maker doesn't say so. Apart from checking for Aluminium it would be useful to see how easy the large sizes are to bend.

Got all excited looking at discarded farm water pipe, there's about 10 metres of 28mm diameter dumped in the hedge. Slight problem, it's plain plastic with no barrier of any kind as used by Larry's red-necks...

If I bite the bullet and order a 50m roll I can guarantee finding a skip full of the stuff within days!

Dave

Have got a coil of unused Pex pipe 16mm, left over from when i laid my underfloor heating.......how much do you need ? PM me your address and i will send you it.

Just read your post above mine, john guest barrier pipe doesnt use aluminium as the barrier, its all plastic.

Wickes barrier pipe (White grey white) has a Polybutylene barrier, the only blue they do is MDPE which is plastic all the way through as used by water utilities as well as rednecks. Oh and they do blue appliance hoses too. They also do Polyplumb barrier pipe (Grey black Grey) which is all plastic.

Edited By JasonB on 10/12/2018 15:46:11

> Wickes barrier pipe (White grey white) has a Polybutylene barrier,

So that won't be any use to you then.

I think you should machine a loop from a billet of pure unobtanium.

Neil

Dave (SoD),

After reading this thread and the 'advice' (?), I'm glad its not me trying to find this stuff in the UK. I get the impression that no-one reads what is written, or looks at the links.

As I noted, if you get stuck, let me know, and I will try and see if I can send some to the UK - maybe DHL or FEDEX shouldn't be too pricey. As of this afternoon, it costs the equivalent of about 20 pence per metre. The postage will probably cost more. If I can send it, then it probably won't be possible until after Christmas now.

I have another suggestion, considering the comments about its diameter. I assume that since this is for a loop antenna, then the ends will not be connected, which should not cause any problems. Just in case you do need to connect to the stuff, all the fittings sold here are made of brass, and the connection is made by a spigot pushing into the pipe, and locked in place by a screw-fitting compression ring. Normally the fitting is isolated by the plastic, but it is a trivial matter to strip some of the plastic back, and fold a strip of the aluminium back under the compression ring.

I know this is changing the question, but wouldn't it be just as easy to use 10mm copper pipe? make a former from plywood with a jigsaw connected to a radius bar and bend it round

i think the pipe your looking for is called protecta line its used in contaminated ground

Edited By david sanderson 3 on 10/12/2018 19:28:56

Anything wrong with using plain aluminium tube, or do you just want to make it as complicated and difficult as possible? I suspect the latter.

Protecta-line won't be the cheap option Dave was looking for that's is £5-6 a meter

I did check, zoomed in on one of the photos, DIN4726 PE-Xc/AL/PE-Xc so it looks like it has.
May not help of course, as I don't know where Dave lives.

Bill

Dave, some other loop ideas...

First, Redsetter... Not sure why your response that Dave is trying to make it as difficult as possible..It is a neat solution, and Duncan, in response to your suggestion of copper tube as well -  The plastic coating on the Aluminium conductor has a dielectric constant greater than one, allowing a smaller loop for a given resonant frequency, so plain copper will require re-calculating the loop dimensions, depending on the loop tuning mechanism.

I am not quite sure what type of loop antenna this is - maybe Dave can enlighten? Is it a loop tuned across an open end by means of a variable capacitor? How do you feed the RF input? Is it via a smaller inductively coupled loop, or a tuned stub?

I have made a few loop antenna for the HF amateur bands, some used a tunable vacuum capacitor and some using a home-brew vane capacitor, but all made from plumbers copper tubing - very easy to make with that tubing, very rigid and quick to modify. A 1.2m diameter loop easily covers from 5MHz to 18MHz with a 30pf to 1800pf tuning capacitor, so if the bespoke tubing is not easily found, try copper tubing with a small increase in diameter.

Here are some of the paths I went down..

This is  1.2m 'diameter' loop - the coax feed to the tuning capacitor runs through the copper tube to the top, across the two open ends is where the tuning cap is fitted.

This is the remotely tuned vacuum cap I made up - The copper tubes fit into the open ends of the loop. The cap is a commercial COMET cap. 10KV, 1500PF max.

This is a vane type variable cap I made - the two copper tubes on the left fit into the loop open ends.

The cap was able to withstand 8KV, ie, 500watts on HF..

The remote tuning hardware as fitted..

All the vanes were water jet cut from aluminium and copper sheet. The Moving vanes are 120mm X 70mm

Just some ideas as alternatives to the tubing you seek..

Joe

usual typo's..

Edited By Joseph Noci 1 on 10/12/2018 20:08:33

I'm in darkest Somerset, so Buxton is a bit of a stretch. As is importing it from the continent (thanks ANOther!)

I was hoping to find the European version readily available in the UK. It's recommended because it's cheap and easily bent to the right shape - a few minutes work. It's a DIY store product abroad. What I'm finding is that the UK types are rather heavier, significantly more expensive and harder to source. I can buy it by the roll from the internet, but 25 or 50m is more than I need.

Here's an example of a cheap pipe loop - very straightforward, and I need two:

It is possible to make the loop from other types of pipe. This pair is in 10mm copper:

But see the additional complication. Each loop is made as a pair in parallel to reduce the inductance. The copper is also a bit pricey.

Professional loops of this type are made from Aluminium tube. Two objections: the 3m length of stiff tube I would have to transport; and bending it neatly. The professionals have bending machines.

Copper is easier to bend than aluminium but it would soon get expensive if I kinked the pipe and had to start again! Again 3m lengths are inconvenient for me to handle. To bend the pipe without a machine I would fill the pipe with sand and wrap it round a former - I feel that's less trouble than bending it section by section on a short coil spring. Certainly do-able but far more trouble do this in copper than pulling a bendy plastic pipe into shape!

Rules of the game:

• Copper or aluminium : wall thickness doesn't matter.
• Preferably no joints.
• Easily bent in a circle. (Circle preferred to other shapes because it maximises the area enclosed within a minimum inductance.)
• Two similar loops required. As performance depends partly on balance, ideally the two loops would be identical but it's not that critical.
• Diameter of tube big rather than small to minimise inductance (10mm requires parallel loops). But wide tubes are harder to bend.
• Cheap
• Able to resist ordinary bad weather for a year.

Suggestions so far have been very helpful. If I don't end up with a simple cheap solution it wasn't for lack of trying!

Thanks again,

Dave

Edited By SillyOldDuffer on 10/12/2018 20:58:28

Dave, I'll ask on a BT/GPO telecoms forum on your behalf, if 1/4" OD pipe would fit your needs or to experiment with parallel loops.
It's used to link up the compressor in each exchange to the underground cables, which run under a +ve pressure of dried air to help exclude water from any damaged sections.

Its an aluminium alloy pipe, with a white plastic coating, and is easily bendable without kinking.

If you have any local BT/Openreach contacts, its used on the ECP (External Cable Pressure) racks and comes in a loose roll in a box. It holds its form reasonably well when bent.

Ali tube is 1/4" OD with a wall thickness of 0.050"

Overall OD is about 0.33"

The bore is clean inside, the scratches below are where I quickly de-burred a bit to measure the wall thickness.

Edited By peak4 on 10/12/2018 21:29:39

Thanks Joe,

Nice pictures from you as usual - I wish I had your brains, energy and skill. I love a well-made variable capacitor that can handle a bit of power!

I'm in the process of discovering that my house is in a painfully poor HF location. My garden is on the small size and the position of the house makes it awkward to run and feed wire antennas. The really difficult part is I live on a street corner and the house has telephone wires on three sides. Quite noisy in a village at the best of times due to overhead power lines everywhere but ADSL and VDSL leakage has added another level of misery. Got even worse after dark last week - I strongly suspect xmas lighting.

I've started using WSPR to test alternative transmit antennas from 80m up. But there's not much point in transmitting if I can't hear replies due to noise. I've bought a KiwiSDR as part of the investigations. It can waterfall 0-30MHz in one go and has 4 separate receivers, and is proving useful as a way of seeing how the noise is distributed as well as identifying the sources.

The antenna I'm making is an untuned broadband receive loop to feed the Kiwi. I had some success balancing noise out with a doublet (unfortunately not suitable as a permanent solution) and am hoping a small loop might do better.

Building a tuned transmit loop like yours is also a possible solution. The hard part is the high voltage capacitor, tuning it remotely, and keeping it dry! I'm concentrating on wires for transmit at the moment because I'm more interested in 3.5, 7, & 10 than the higher bands

Edited By SillyOldDuffer on 10/12/2018 22:03:20

Dave, Just messaged the seller of the stuff he's got spare in Buxton.
It's labelled "UHM LTD STUTTGART" if that's any assistance to you in your search.

Good luck

Bill

Dave,

Amazingly, in our little coastal town here, we have the tubing you are after! In 12mm and 20mm diameters - It is used extensively now, it seems, in plumbing all new house builds, But that does not really help you, I guess! Seems around 80p per meter for the 12mm pipe.

As for brains, not sure ...I just dig and persevere till I think I know what I need to know and get on with it!

A bit of the piping topic, but likewise, I have a very poor HF location. Although I am 40 or so meters from the edge of the ocean, with a clean HF view to the west, My east north and south is a noisy nightmare - lots of power line RF control of geysers , and that stuff is trash - lots if RFI and I have an ongoing fight with the local council and our Radio Regulatory institution ( CRAN) for the last 4 years - getting nowhere fast.

So I tried some other ideas, which may interest you - I built this noise canceller device ( you may be able to purchase one in the UK?) -

**LINK**

**LINK**

I always regarded this sort of device with suspicion but this one really worked well for me - it did really reduce my ambient noise by a good 3 to 4 S points!

Basically takes an ambient RF sample from its own small wire antenna and adds that to the signal from the main antenna ( your loop..) in a manipulated manner - phase shifts it in relation to the main signal, so that there is cancellation. You move the sampler antenna around till you get the best cancellation, while also fiddling with the phasing controls. Takes a little while of mucking about, but the results are well worth it!

With respect to a loop with joints - you lose nothing by using 20mm copper tubing, with the 45deg elbows, and solder the joints properly. The current flow in a loop antenna on transmit is very high, and due to the skin effect, resistance of the antenna plays a big roll - clean copper wins hands down against clean aluminium, but any oxidation on either can reduce the efficiency from 3 or 4% to 1-2%...

Also, the 'diameter' increase needed to enclose the same circle area by using an octagon shape is very small and will not impact the size in any detrimental manner I would think.

The Al piping may fair better in that the Al material is kept from oxidising by the plastic covering - I scrubbed my copper loop with pot scouring pads and then gave the loop a coat of clear two-part epoxy paint. That survived around 8 years.

The vane capacitor was enclosed in a box made from 5mm PVC sheet, and all pipe exits were sealed with silicone. The tuning of that cap was done by means of an RC servo, with a simple RC servo tester providing the 1ms to 2ms pulse train. Tuning was effected by watching the SWR meter and tuning for lowest SWR. You can a also tune on maximum received noise, but I had such a crappy ( digital) servo in the beginning , it generated so much noise itself that it masked the signal! When I replaced it with an old analogue servo that method worked ok.

Dave, I have one of those COMET vacumm capacitors still - good for 10KV, I believe - Had it for 12 years or so and will never use it - I could try get it to you? Not sure how much shipping would be and what the complexities are at your end for its import? It is about 220mm long and 90mm diameter, maybe 1kg or so. Solves some of the issues of keeping it dry, etc..Even a study plastic bag and tie wraps would work! You are welcome to it..

Regarding the band you are working - Generally a minimum loop diameter of 1.2 to 1.5m is recommended to cover 5MHz to 16MHz with 'some' usable transmit efficiency, and a diameter of 2 to 2.2m for 3MHz to 8MHz.

The smaller the diameter the greater the capacitance has to be to tune the lower bands, the higher the loop current and the greater the loop end voltage the cap has to withstand. A 1m diameter loop at 3.5MHz may need around 400pf ( depends on many things, pipe diameter, material, etc) and the cap would see around 15KV at 100 watts drive...A 2.5m loop would drop that voltage to around 8KV - please note, these are severe generalisations, but the variance in voltage due to loop diameter is what matters, not the actual value.

I eventually gave up with loops - I found no advantage over a simple inverted V, other than the neat ability to be able to rotate the loop to null out an interfering signal. Although I must say that the loop was a little quieter since it is a magnetic receptor and does not really respond to the electrical portion of a radio wave, which is what most mane-made interference consists off! But generally the loop was 1 to 2 S points down on the inverted V..

I am interested to understand your 'broad band' statement for loops - Loops are inherently VERY narrow band - a few percent at best, and tune very sharply - any broad bandness is a sure sign of big losses, ie, approaching a dummy load rather than an antenna!

Forgive my (long) topic drift, but I suspect it is in line with what you are doing anyway!

Joe

Dave, you can get it on e-bay my the meter but it does work out pricy, same seller does 5, 7.5, 10 and 20m lengths.

20m seems best buy for you at £18 inc postage

Jason, you are my hero! That's a better price than any of the suppliers I found yesterday and I don't have to buy a 50m roll! I've just ordered 20m.

Thanks

Dave