I'm looking for about 1km of thin-ish solid copper wire, as cheap as 
possible.

1. Solid, not stranded
2. To be used as single wires, in lengths of typically 10m
3. Could be insulated or bare, tinned or not; but not enamelled (unless 
the price was very, very right)
4. Strong enough to cope with being laid on the ground outdoors, and 
then generally trodden on and mowed over
5. Thin enough to be cheap.

About 1.0-1.5mm diameter would probably be fine.

In the catalogues, the best options so far seem to be multi-core cables 
of some kind. 12-core telephone cable is a reasonable price from TLC, 
though it's thinner than I'd prefer, and I'd rather not to have to strip 
and untwist it to get to the individual wires.

Solid twin bell wire from TLC would be fine, but significantly dearer 
per 100m of single wire. (Screwfix bell wire is stranded, so no use for 
this.)

Any better ideas from you intrepid bargain hunters, please?



-- 
Ian White

In article <+ralX2LemljCFAPm@ifwtech.co.uk>,
   Ian White  wrote:

> I'm looking for about 1km of thin-ish solid copper wire, as cheap as 
> possible.

> 1. Solid, not stranded
> 2. To be used as single wires, in lengths of typically 10m
> 3. Could be insulated or bare, tinned or not; but not enamelled (unless 
> the price was very, very right)
> 4. Strong enough to cope with being laid on the ground outdoors, and 
> then generally trodden on and mowed over
> 5. Thin enough to be cheap.

> About 1.0-1.5mm diameter would probably be fine.

> In the catalogues, the best options so far seem to be multi-core cables 
> of some kind. 12-core telephone cable is a reasonable price from TLC, 
> though it's thinner than I'd prefer, and I'd rather not to have to strip 
> and untwist it to get to the individual wires.

> Solid twin bell wire from TLC would be fine, but significantly dearer 
> per 100m of single wire. (Screwfix bell wire is stranded, so no use for 
> this.)

> Any better ideas from you intrepid bargain hunters, please?


You need to specify either cross sectional area, SWG, or what current it
has to carry.

Single core insulated for electronic stuff is available from RS Components
etc. Go up to normal mains - ie 1mm/sq and above and you'll get it at any
electrical wholesaler. Single core is used in conduit, etc.

-- 
*Many hamsters only blink one eye at a time *

    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

On Fri, 20 May 2005 22:41:50 퍝, Ian White wrote:


> About 1.0-1.5mm diameter would probably be fine.


A quick look on RS shows 500m of 1/0.8mm at £26.72  VAT code 183-9231for white also available in blue or brown.

-- 
Cheers                                              new5pam@howhill.com
Dave.                                             pam is missing e-mail

Dave Liquorice wrote:


>>About 1.0-1.5mm diameter would probably be fine.
> 
> 
> A quick look on RS shows 500m of 1/0.8mm at 26.72 + VAT code 183-9231 
> for white also available in blue or brown.



I don't see how any thin wire can satisfy "Strong enough to cope with 
being laid on the ground outdoors, and then generally trodden on and 
mowed over". I don't think even CAT5 or T&E can withstand these 
conditions long term.


-- 
Grunff

Ian White wrote:


> I'm looking for about 1km of thin-ish solid copper wire


It might help if you gave a hint *what* you want to use it for, from
your description hopefully it wouldn't be for carrying 240v ...

Ian White wrote:


> I'm looking for about 1km of thin-ish solid copper wire, as cheap as 
> possible.
> 
> 1. Solid, not stranded
> 2. To be used as single wires, in lengths of typically 10m
> 3. Could be insulated or bare, tinned or not; but not enamelled (unless 
> the price was very, very right)
> 4. Strong enough to cope with being laid on the ground outdoors, and 
> then generally trodden on and mowed over
> 5. Thin enough to be cheap.


RF groundplane: earth mat or radial system for a vertical radiator?  Try 
http://www.ormiston-wire.co.uk/ or G. Barmaper in Stanmore.  Or get some 
  7-strand conduit wire (say 10 or 16 mm^2) and strip out the strands.

73
-- 
Andy

In article <428e71d7$0$18805$da0feed9@news.zen.co.uk>, Grunff
 writes

>Dave Liquorice wrote:
>
>>>About 1.0-1.5mm diameter would probably be fine.
>> 
>> 
>> A quick look on RS shows 500m of 1/0.8mm at 26.72 + VAT code 183-9231 
>> for white also available in blue or brown.
>
>
>I don't see how any thin wire can satisfy "Strong enough to cope with 
>being laid on the ground outdoors, and then generally trodden on and 
>mowed over". I don't think even CAT5 or T&E can withstand these 
>conditions long term.
>
>


What?,, Do you want to use it for?.....
-- 
Tony Sayer

Thanks very much for the replies so far. I really do appreciate how you 
lot get your teeth into an unusual problem!

But I misjudged the amount of detail that people might need in order to 
give a helpful reply. My apologies for that - I was trying to spare you 
all "the full half-hour". Well, here it comes...

This is a rather unusual application, and many of the normal electrical 
wiring requirements do not apply.


>> I'm looking for about 1km of thin-ish solid copper wire, as cheap as
>> possible.


Yes, Andy, it is to make a ground mat for a radio aerial... well, four 
aerials actually! This requires the wires to be laid out in a fairly 
precise pattern of four radial fans, and the ends soldered to bare 
copper "busbars".

BTDT before, but only on a smaller scale requiring much less wire. This 
time I'm doing it at a new location and on a much bigger scale.

The amount of wire required - literally more than a kilometre - means 
that (a) I'll have to buy it, and (b) paying the odd few pence more per 
metre will add up to serious money.

The number of separate lengths of wires involved - approaching 200 - 
means I have to think about easy "mass production" techniques. Many of 
the things you wouldn't hesitate to do for a few tens of metres are 
simply not on at the kilometre scale. Wire's too long; life's too short.


>
>> 1. Solid, not stranded


That is an absolute requirement - please take my word for it. (At radio 
frequencies, the resistance of stranded wire becomes much higher when 
the strands corrode, as they inevitably will over the years. Solid wire 
is much less affected.)


>> 2. To be used as single wires, in lengths of typically 10m
>> 3. Could be insulated or bare, tinned or not;


 From the performance point of view, it makes no difference whether the 
wire is insulated or not (see, I told you this was unusual).


>>but not enamelled (unless
>> the price was very, very right)


BTDT - enamelled is a pain to scrape and connect, especially when doing 
it about 200 times, outdoors at ground level.


>> 4. Strong enough to cope with being laid on the ground outdoors, and
>> then generally trodden on and mowed over
>> About 1.0-1.5mm diameter would probably be fine.

 >>

Sorry, Grunff, I may have misled you by not specifying the kind of 
surface. On grassy land, 1.5mm diameter copper is plenty strong enough 
for the basic radial wires - strong enough to trip someone up, and it 
will even stop a rotary mower (it cuts the wire, but the wire wins in 
the end, by strangulation).

The trick when laying wires on grass is to mow the grass very short 
first. Then lay the wires along the ground, heel down any sticking-up 
loops, or pin them down with thicker wire 'staples'... and then simply 
leave them. Just carry on mowing a bit higher than usual (which is where 
you find any loops that you didn't pin down properly) and within a year 
the wires will have disappeared under the root mat. It's quite 
remarkable. Within two years, you'll even have to search for half-inch 
cables.


>
>> 5. Thin enough to be cheap.


As I said, on this scale the price per metre of wire really does matter 
- especially bearing in mind it's only for a hobby. Each extra penny per 
metre becomes another 10 quid on the total cost.

Dave said:

>You need to specify either cross sectional area, SWG, or what current it
>has to carry.
>

I'd hoped to get away without having to go into details, Dave... but 
judging by some of the questions we get on here, you were quite right to 
ask  :-)

For this unusual application, most of the normal electrical wiring 
factors don't matter at all. It all comes down to mechanical strength, 
and price.



>Single core insulated for electronic stuff is available from RS Components
>etc. Go up to normal mains - ie 1mm/sq and above and you'll get it at any
>electrical wholesaler.


If buying at normal catalogue prices, I'd rather spend all the money on 
copper than on insulation that isn't needed.  However, plain bare solid 
copper seems to be the province of "instrument wire" suppliers, and is 
sold at a huge premium compared with the copper content of say T&E.


> Single core is used in conduit, etc.
>

Stranded, alas. That is the one definite no-no for this particular 
application.

Andy said:

>Or get some  7-strand conduit wire (say 10 or 16 mm^2) and strip out 
>the strands.


Because of the total length of wire involved, I'm afraid that would be 
far too labour-intensive. The same would apply to options such as 
stripping down scrap T&E. It's got to be some kind of wire that allows 
an easy "mass production" technique.

Tricky... but I really do appreciate your help and good thinking.


-- 
Ian White

In article ,
   Ian White  wrote:
[snip]

> BTDT - enamelled is a pain to scrape and connect, especially when
> doing it about 200 times, outdoors at ground level.


 There is a low-temperature enamel which melts at
 (high) soldering temperatures.  Tradename 'Quikstrip'
 afair, and is a light salmon-pink coloured enamel.
 Most of the en-cu in RS is Quikstrip I think.

-- 
Tony Williams.

Ian White wrote:


> Yes, Andy, it is to make a ground mat for a radio aerial... 


I did wonder ....


> BTDT - enamelled is a pain to scrape and connect


Dip the end in meths and burn it off? still a bit of messy to clean if
you're neeed to solder (and repeat 200 times)

tony sayer wrote:


> What?,, Do you want to use it for?.....



I don't, I'm not the OP!


-- 
Grunff

In article , Ian White
 writes

>Thanks very much for the replies so far. I really do appreciate how you 
>lot get your teeth into an unusual problem!
>
>But I misjudged the amount of detail that people might need in order to 
>give a helpful reply. My apologies for that - I was trying to spare you 
>all "the full half-hour". Well, here it comes...
>
>This is a rather unusual application, and many of the normal electrical 
>wiring requirements do not apply.
>
>>> I'm looking for about 1km of thin-ish solid copper wire, as cheap as
>>> possible.
>
>Yes, Andy, it is to make a ground mat for a radio aerial... well, four 
>aerials actually! This requires the wires to be laid out in a fairly 
>precise pattern of four radial fans, and the ends soldered to bare 
>copper "busbars".


You should be over on uk.tech.broadcast for that sort of thing:!...

>
>BTDT before, but only on a smaller scale requiring much less wire. This 
>time I'm doing it at a new location and on a much bigger scale.
>
>The amount of wire required - literally more than a kilometre - means 
>that (a) I'll have to buy it, and (b) paying the odd few pence more per 
>metre will add up to serious money.


Building some medium powered MF station?.......
-- 
Tony Sayer

Bancom Communications Ltd U.K. Tel+44 1223 566577 Fax+44 1223 566588

P.O. Box 280, Cambridge, England, CB2 2DY    E-Mail tony@bancom.co.uk

In article ,
   Ian White  wrote:

> > Single core is used in conduit, etc.
> >
> Stranded, alas. That is the one definite no-no for this particular 
> application.


All the 1 - 1.5mm singles I've seen are solid core. 2.5mm may be either
solid or stranded.

-- 
*If horrific means to make horrible, does terrific mean to make terrible?

    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

Ian White wrote:

> I'm looking for about 1km of thin-ish solid copper wire, as cheap as 
> possible.
> 1. Solid, not stranded
> 2. To be used as single wires, in lengths of typically 10m
> 3. Could be insulated or bare, tinned or not; but not enamelled (unless 
> the price was very, very right)
> 4. Strong enough to cope with being laid on the ground outdoors, and 
> then generally trodden on and mowed over
> 5. Thin enough to be cheap.
> About 1.0-1.5mm diameter would probably be fine.


As it doesn't have to be insulated, if it didn't have to be copper, I'd 
suggest looking at fencing wire.

If it could be stranded I'd suggest looking at electric fence wire.

Owain

In article <6$YNBtEXOwjCFwu8@bancom.co.uk>,
   tony sayer  wrote:

> >Yes, Andy, it is to make a ground mat for a radio aerial... well, four 
> >aerials actually! This requires the wires to be laid out in a fairly 
> >precise pattern of four radial fans, and the ends soldered to bare 
> >copper "busbars".

> You should be over on uk.tech.broadcast for that sort of thing:!...


Hmm. Surely there are amateur radio groups that would be better suited?

-- 
*Don't sweat the petty things and don't pet the sweaty things.

    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

In article , Dave Plowman (News)
 writes

>In article <6$YNBtEXOwjCFwu8@bancom.co.uk>,
>   tony sayer  wrote:
>> >Yes, Andy, it is to make a ground mat for a radio aerial... well, four 
>> >aerials actually! This requires the wires to be laid out in a fairly 
>> >precise pattern of four radial fans, and the ends soldered to bare 
>> >copper "busbars".
>
>> You should be over on uk.tech.broadcast for that sort of thing:!...
>
>Hmm. Surely there are amateur radio groups that would be better suited?
>


I don't think amateur groups do that sort of size earth mat system
Sounds like some sort of broadcast application......
-- 
Tony Sayer

"Dave Plowman (News)"  writes:

>In article <6$YNBtEXOwjCFwu8@bancom.co.uk>,
>   tony sayer  wrote:
>> >Yes, Andy, it is to make a ground mat for a radio aerial... well, four 
>> >aerials actually! This requires the wires to be laid out in a fairly 
>> >precise pattern of four radial fans, and the ends soldered to bare 
>> >copper "busbars".
>
>> You should be over on uk.tech.broadcast for that sort of thing:!...
>
>Hmm. Surely there are amateur radio groups that would be better suited?


Well, there's uk.radio.amateur, but that means being in the same place as
Walt Davidson, who makes IMM look like an intellectual giant.


-- 
       "The road to Paradise is through Intercourse."
        [email me at huge [at] huge [dot] org [dot] uk]

tony sayer  writes:

>In article , Ian White
> writes
>>Thanks very much for the replies so far. I really do appreciate how you 
>>lot get your teeth into an unusual problem!
>>
>>But I misjudged the amount of detail that people might need in order to 
>>give a helpful reply. My apologies for that - I was trying to spare you 
>>all "the full half-hour". Well, here it comes...
>>
>>This is a rather unusual application, and many of the normal electrical 
>>wiring requirements do not apply.
>>
>>>> I'm looking for about 1km of thin-ish solid copper wire, as cheap as
>>>> possible.
>>
>>Yes, Andy, it is to make a ground mat for a radio aerial... well, four 
>>aerials actually! This requires the wires to be laid out in a fairly 
>>precise pattern of four radial fans, and the ends soldered to bare 
>>copper "busbars".


Way overkill. If this is mostly over grass, cuut it very short, pin
chicken wire flat against the ground and wait. After a couple of years,
it will have vanished into the ground.

Or so I am told. My aerials are in bits in the orchard.



-- 
       "The road to Paradise is through Intercourse."
        [email me at huge [at] huge [dot] org [dot] uk]

Ian White wrote:


> Thanks very much for the replies so far. I really do appreciate how you 
> lot get your teeth into an unusual problem!
> 
> But I misjudged the amount of detail that people might need in order to 
> give a helpful reply. My apologies for that - I was trying to spare you 
> all "the full half-hour". Well, here it comes...

<snip>

Try a cabling company like Nimans etc.
Although I would have thought that simply laying concrete reinforcing 
mesh would have been good enough...

tony sayer wrote:

>In article , Dave Plowman (News)
> writes
>>In article <6$YNBtEXOwjCFwu8@bancom.co.uk>,
>>   tony sayer  wrote:
>>> >Yes, Andy, it is to make a ground mat for a radio aerial... well, four
>>> >aerials actually! This requires the wires to be laid out in a fairly
>>> >precise pattern of four radial fans, and the ends soldered to bare
>>> >copper "busbars".
>>
>>> You should be over on uk.tech.broadcast for that sort of thing:!...
>>
>>Hmm. Surely there are amateur radio groups that would be better suited?
>>

No - I contribute to several of those groups and lists, and can assure 
you that despite it being an unusual kind of DIY problem, here *is* the 
best place to ask.


>
>I don't think amateur groups do that sort of size earth mat system


Oh yes we do - and what I'm proposing is actually a little one.

For a serious earth mat that would put many broadcasters to shame, see:
http://nidxa.org/memberWWW/k9dx_antennas.htm
There's about 40km of wire under there. I book-marked that page to 
remind myself occasionally that maybe 1km isn't so hard after all...


-- 
Ian White

On Fri, 20 May 2005 22:41:50 +0100, Ian White  wrote:


>I'm looking for about 1km of thin-ish solid copper wire, as cheap as 
>possible.


D10 - mil-surplus field telephone wire. Comes as two separate wires,
loosely twisted into a pair. Easily unravelled.

It's stranded, which is better. Solid core used outdoor in these lengths
will break and it's a royal pain to find where.

Huge wrote:

>>>Yes, Andy, it is to make a ground mat for a radio aerial... well, four
>>>aerials actually! This requires the wires to be laid out in a fairly
>>>precise pattern of four radial fans, and the ends soldered to bare
>>>copper "busbars".
>
>Way overkill. If this is mostly over grass, cuut it very short, pin 
>chicken wire flat against the ground and wait. After a couple of years, 
>it will have vanished into the ground.
>


I did wonder about that, because it's so quick and easy to lay down.

However, the previous occupants have thoughtfully left behind some "test 
samples", which show that in these ground conditions it will be rusting 
through within about 10 years... by which time it will have become 
impossible to rip up without ruining the entire area.

The advantage of copper wires is that they will last indefinitely, yet 
they can still be pulled out one by one (which I just did that at the 
old place).


-- 
Ian White

On Fri, 20 May 2005 22:41:50 +0100, Ian White 
wrote:



>1. Solid, not stranded


How about Military Surplus telephone cable, D10
(http://www.brand-rex.com/xtreme/prods/datsheet/defence/Def01.pdf) it
isn't stranded but is insulated with a PVC coat and nylon sheath so
won't corrode for years.  It is far tougher than most cables (3
steel/4copper strands per core) and usually sells for about GBP10 per
1km pack.

If single core is an absolute BDC/Micromark do a twin bell wire.
Each conductor is single core PVC insulated 0.38mm x sec area in a
figure of 8 configuration so fairly easy to separate.  That is
GBP4.80 per 100m ex VAT.

-- 
Peter Parry.   
http://www.wpp.ltd.uk/

Ian White wrote:


> Yes, Andy, it is to make a ground mat for a radio aerial...


How did I guess...?


> well, four aerials actually!


Ah, phased verticals (?)


>>> 1. Solid, not stranded
> That is an absolute requirement - please take my word for it. (At radio 
> frequencies, the resistance of stranded wire becomes much higher when 
> the strands corrode, as they inevitably will over the years. Solid wire 
> is much less affected.)


Hmm, I've not come across that one before.  It used to be quite common 
practice to use 7/36 stranded bare copper for (MF & HF) radio earth 
systems.  Presumably you're suggesting that the inter-strand corrosion 
increases the RF resistance somehow - yet the current flow is 
longitudinal and surface corrosion of a single wire will also increase 
the RF resistance.  Further explanation and scientific evidence would be 
of interest.


> BTDT - enamelled is a pain to scrape and connect, especially when doing 
> it about 200 times, outdoors at ground level.


But surely almost all 'enamelled' wire these days is solderable 
polyurethane insulated and won't need scraping.  It needs a hot iron (or 
flame) for soldering and emits toxic fumes (toluene di-isocyanate) - but 
I'm sure you know that already.


> The trick when laying wires on grass is to mow the grass very short 
> first. Then lay the wires along the ground, heel down any sticking-up 
> loops, or pin them down with thicker wire 'staples'... and then simply 
> leave them. Just carry on mowing a bit higher than usual (which is where 
> you find any loops that you didn't pin down properly) and within a year 
> the wires will have disappeared under the root mat. It's quite 
> remarkable. Within two years, you'll even have to search for half-inch 
> cables.


Interesting. When I used to operate on 160m (a long time ago) I used to 
dig a narrow slit and push the wire down a few inches.


> If buying at normal catalogue prices, I'd rather spend all the money on 
> copper than on insulation that isn't needed.  However, plain bare solid 
> copper seems to be the province of "instrument wire" suppliers, and is 
> sold at a huge premium compared with the copper content of say T&E.


The trouble is that to a wire supplier 1 km is a small quantity and 
doesn't give you much buying power.  Nevertheless you should be able to 
buy bare or tinned wire in 500m reels at much better prices than in the 
RS or Farnell catalogues.  I reckon you're after roughly 10 kg of copper 
in total.


>> Single core is used in conduit, etc.
> Stranded, alas. That is the one definite no-no for this particular 
> application.


You can get 6491X PVC insulated conduit wire in solid (single-strand) up 
to 2.5 mm^2.  (But PVC is a poor dielectric and might also add 
significant RF loss.)


> Andy said:
>> Or get some  7-strand conduit wire (say 10 or 16 mm^2) and strip out 
>> the strands.
> Because of the total length of wire involved, I'm afraid that would be 
> far too labour-intensive.


YIK, but it did meet the "cheap" part of the specification.

-- 
Andy

Peter Parry wrote:


>
>>1. Solid, not stranded
>
>How about Military Surplus telephone cable, D10
>(http://www.brand-rex.com/xtreme/prods/datsheet/defence/Def01.pdf) it
>isn't stranded

  (typo: isn't solid / is stranded)

>but is insulated with a PVC coat and nylon sheath so
>won't corrode for years.  It is far tougher than most cables (3
>steel/4copper strands per core) and usually sells for about GBP10 per
>1km pack.
>


Similarly, Andy Dingley wrote:

>D10 - mil-surplus field telephone wire. Comes as two separate wires,
>loosely twisted into a pair. Easily unravelled.


Thank you, both. With that kind of extra-tough insulation, stranded wire 
would be just fine.

A quick Google found Ramco in Skegness selling D10 on eBay at GBP40 for 
800m (though a friend in the area could no doubt get it for less). 
Anyone else you know of... a bit closer to PP's GBP10/km mark, maybe?

Getting warmer! Told you this was the right place to ask :-)



-- 
Ian White

Ian White wrote:

> Thanks very much for the replies so far. I really do appreciate how
you
> lot get your teeth into an unusual problem!
>
> But I misjudged the amount of detail that people might need in order
to
> give a helpful reply. My apologies for that - I was trying to spare
you
> all "the full half-hour". Well, here it comes...
>
> This is a rather unusual application, and many of the normal
electrical
> wiring requirements do not apply.
>
> >> I'm looking for about 1km of thin-ish solid copper wire, as cheap
as
> >> possible.
>
> Yes, Andy, it is to make a ground mat for a radio aerial... well,
four
> aerials actually! This requires the wires to be laid out in a fairly
> precise pattern of four radial fans, and the ends soldered to bare
> copper "busbars".
>
> BTDT before, but only on a smaller scale requiring much less wire.
This
> time I'm doing it at a new location and on a much bigger scale.
>
> The amount of wire required - literally more than a kilometre - means

> that (a) I'll have to buy it, and (b) paying the odd few pence more
per
> metre will add up to serious money.
>
> The number of separate lengths of wires involved - approaching 200 -
> means I have to think about easy "mass production" techniques. Many
of
> the things you wouldn't hesitate to do for a few tens of metres are
> simply not on at the kilometre scale. Wire's too long; life's too
short.
>
> >
> >> 1. Solid, not stranded
>
> That is an absolute requirement - please take my word for it. (At
radio
> frequencies, the resistance of stranded wire becomes much higher when

> the strands corrode, as they inevitably will over the years. Solid
wire
> is much less affected.)
>
> >> 2. To be used as single wires, in lengths of typically 10m
> >> 3. Could be insulated or bare, tinned or not;
>
>  From the performance point of view, it makes no difference whether
the
> wire is insulated or not (see, I told you this was unusual).
>
> >>but not enamelled (unless
> >> the price was very, very right)
>
> BTDT - enamelled is a pain to scrape and connect, especially when
doing
> it about 200 times, outdoors at ground level.
>
> >> 4. Strong enough to cope with being laid on the ground outdoors,
and
> >> then generally trodden on and mowed over
> >> About 1.0-1.5mm diameter would probably be fine.
>  >>
>
> Sorry, Grunff, I may have misled you by not specifying the kind of
> surface. On grassy land, 1.5mm diameter copper is plenty strong
enough
> for the basic radial wires - strong enough to trip someone up, and it

> will even stop a rotary mower (it cuts the wire, but the wire wins in

> the end, by strangulation).
>
> The trick when laying wires on grass is to mow the grass very short
> first. Then lay the wires along the ground, heel down any sticking-up

> loops, or pin them down with thicker wire 'staples'... and then
simply
> leave them. Just carry on mowing a bit higher than usual (which is
where
> you find any loops that you didn't pin down properly) and within a
year
> the wires will have disappeared under the root mat. It's quite
> remarkable. Within two years, you'll even have to search for
half-inch
> cables.
>
> >
> >> 5. Thin enough to be cheap.
>
> As I said, on this scale the price per metre of wire really does
matter
> - especially bearing in mind it's only for a hobby. Each extra penny
per
> metre becomes another 10 quid on the total cost.
>
> Dave said:
> >You need to specify either cross sectional area, SWG, or what
current it
> >has to carry.
> >
> I'd hoped to get away without having to go into details, Dave... but
> judging by some of the questions we get on here, you were quite right
to
> ask  :-)
>
> For this unusual application, most of the normal electrical wiring
> factors don't matter at all. It all comes down to mechanical
strength,
> and price.
>
>
> >Single core insulated for electronic stuff is available from RS
Components
> >etc. Go up to normal mains - ie 1mm/sq and above and you'll get it
at any
> >electrical wholesaler.
>
> If buying at normal catalogue prices, I'd rather spend all the money
on
> copper than on insulation that isn't needed.  However, plain bare
solid
> copper seems to be the province of "instrument wire" suppliers, and
is
> sold at a huge premium compared with the copper content of say T&E.
>
> > Single core is used in conduit, etc.
> >
> Stranded, alas. That is the one definite no-no for this particular
> application.
>
> Andy said:
> >Or get some  7-strand conduit wire (say 10 or 16 mm^2) and strip out

> >the strands.
>
> Because of the total length of wire involved, I'm afraid that would
be
> far too labour-intensive. The same would apply to options such as
> stripping down scrap T&E. It's got to be some kind of wire that
allows
> an easy "mass production" technique.
>
> Tricky... but I really do appreciate your help and good thinking.
>
>
> --
> Ian White



Some options:

1. go with bare copper 1.5mm wire

2. I guess copper coated steel would be cheaper and tougher, but have
no idea where or if its available.

3. Use enamelled, very cheap indeed, and a dremel type tool with a
rotary wire brush for superfast stripping.

4. Use assorted scrap. It then doesnt matter if its
- insulated
- T&E
- etc
Just use them as they are, dont strip, dont separate the wires in T&E
etc.


NT

Huge wrote:


>>Hmm. Surely there are amateur radio groups that would be better suited?
> 
> 
> Well, there's uk.radio.amateur, but that means being in the same place as
> Walt Davidson, who makes IMM look like an intellectual giant.


Walts just so much fun though ;-)))

Badger  writes:

>
>
>Huge wrote:
>
>>>Hmm. Surely there are amateur radio groups that would be better suited?
>> 
>> 
>> Well, there's uk.radio.amateur, but that means being in the same place as
>> Walt Davidson, who makes IMM look like an intellectual giant.
>
>Walts just so much fun though ;-)))


The only fun thing about Walt would be watching him burn to death.

-- 
       "The road to Paradise is through Intercourse."
        [email me at huge [at] huge [dot] org [dot] uk]

"Ian White"  wrote in message 
news:3QCXZIK9wujCFA9m@ifwtech.co.uk...
....

> The number of separate lengths of wires involved - approaching 200 - means 
> I have to think about easy "mass production" techniques. Many of the 
> things you wouldn't hesitate to do for a few tens of metres are simply not 
> on at the kilometre scale. Wire's too long; life's too short....


A wire company e.g.

http://www.knight-precision-wire.co.uk/

or Ormiston Wire (who don't seem to have a web site) will sell you the wire 
cut to length and straightened. Even if you want to do the work yourself, 
that will still probably be the cheapest sort of place to buy from.

Colin Bignell

In message <d6ngho$oi0$5@anubis.demon.co.uk>, Huge  
writes

>Badger  writes:
>>
>>
>>Huge wrote:
>>
>>>>Hmm. Surely there are amateur radio groups that would be better suited?
>>>
>>>
>>> Well, there's uk.radio.amateur, but that means being in the same place as
>>> Walt Davidson, who makes IMM look like an intellectual giant.
>>
>>Walts just so much fun though ;-)))
>
>The only fun thing about Walt would be watching him burn to death.
>

More or less the same as dIMM then

-- 
geoff

On 21 May,  
     tony sayer  wrote:


> In article , Dave Plowman (News)
>  writes
> >In article <6$YNBtEXOwjCFwu8@bancom.co.uk>,
> >   tony sayer  wrote:
> >> >Yes, Andy, it is to make a ground mat for a radio aerial... well, four 
> >> >aerials actually! This requires the wires to be laid out in a fairly 
> >> >precise pattern of four radial fans, and the ends soldered to bare 
> >> >copper "busbars".
> >
> >> You should be over on uk.tech.broadcast for that sort of thing:!...
> >
> >Hmm. Surely there are amateur radio groups that would be better suited?
> >
> 
> I don't think amateur groups do that sort of size earth mat system
> Sounds like some sort of broadcast application......


Sounds about right for a vertical on most amateur bands below 14MHz. there is
an LF band noe about 137khz I think, and an mf one at about 1.9MHz.

-- 
  B Thumbs
  Change lycos to yahoo to reply

On 21 May,  
     Ian White  wrote:


> For a serious earth mat that would put many broadcasters to shame, see:
> http://nidxa.org/memberWWW/k9dx_antennas.htm There's about 40km of wire
> under there. I book-marked that page to  remind myself occasionally that
> maybe 1km isn't so hard after all...
> 
> 

Want one for when I next get on 160m.


-- 
  B Thumbs
  Change lycos to yahoo to reply

Ian White wrote:


> For a serious earth mat that would put many broadcasters to
> shame, see: http://nidxa.org/memberWWW/k9dx_antennas.htm
> There's about 40km of wire under there. I book-marked that page to
> remind myself occasionally that maybe 1km isn't so hard after
> all...


http://nidxa.org/memberWWW/k9dx_home.htm
Blimey, wouldn't it be easier to just phone them?

Thats what I call an earth mat Ian!

Peter Crosland

> The only fun thing about Walt would be watching him burn to death.


Far too quick and painless.

Peter Crosland

On Sat, 21 May 2005 14:13:39 +0100, Ian White  wrote:


>Anyone else you know of... a bit closer to PP's GBP10/km mark, maybe?


That's what I paid for what I think was 1km, from Anchor surplus in
Ripley / Nottingham.

On Sat, 21 May 2005 12:48:54 +0100, Ian White wrote:


> However, the previous occupants have thoughtfully left behind some 
> "test samples", which show that in these ground conditions it will 
> be rusting through within about 10 years... by which time it will 
> have become impossible to rip up without ruining the entire area.


Would you need to remove it? Just bung some more down... The lower Z 
of the new stuff shorting out any higher Z bits in the old.

-- 
Cheers                                              new5pam@howhill.com
Dave.                                             pam is missing e-mail

Dave Liquorice wrote:

>On Sat, 21 May 2005 12:48:54 +0100, Ian White wrote:
>
>> However, the previous occupants have thoughtfully left behind some
>> "test samples", which show that in these ground conditions it will
>> be rusting through within about 10 years... by which time it will
>> have become impossible to rip up without ruining the entire area.
>
>Would you need to remove it? Just bung some more down... The lower Z
>of the new stuff shorting out any higher Z bits in the old.
>


And what happens after another 10 years? I would really not like to 
leave the land in that condition.

Just think - in the next life, I might be sent back as a mole.

Or you might  :-)


-- 
Ian White

Andy Wade wrote:

>Ian White wrote:
>
>> Yes, Andy, it is to make a ground mat for a radio aerial...
>
>How did I guess...?
>
>> well, four aerials actually!
>
>Ah, phased verticals (?)
>

That's right. Four verticals at the corners of a 10m square, phased 
together to create a directional beam that is instantly switchable in 
any of eight directions.

Part of the fun of playing with aerials is that it's a mixture of 
electronic engineering and DIY (though I must admit there's not a lot of 
scope for paperhanging).


>>>> 1. Solid, not stranded
>> That is an absolute requirement - please take my word for it. (At 
>>radio  frequencies, the resistance of stranded wire becomes much 
>>higher when  the strands corrode, as they inevitably will over the 
>>years. Solid wire  is much less affected.)
>
>Hmm, I've not come across that one before.  It used to be quite common 
>practice to use 7/36 stranded bare copper for (MF & HF) radio earth 
>systems.  Presumably you're suggesting that the inter-strand corrosion 
>increases the RF resistance somehow - yet the current flow is 
>longitudinal and surface corrosion of a single wire will also increase 
>the RF resistance.  Further explanation and scientific evidence would 
>be of interest.
>

Sorry, this is getting a bit OT, but it might be interesting...

Something called the 'skin effect' makes radio-frequency (RF) currents 
flow only on the outside skin of a conductor. Skin depth decreases with 
frequency (square root of). No current flows within the wire, so its 
current-carrying cross-sectional area is much smaller than its physical 
cross-section. Therefore its effective resistance is higher at RF than 
it is at DC or 50Hz.

The difference between solid wire and stranded is that the current has 
to hop from strand to strand in order to flow straight down the wire, 
because the lay of the strands is slightly spiral. There is only a small 
mechanical force holding adjacent strands together, so the contact is 
never very good and  so the RF resistance is just a little bit higher 
than for the same-size solid wire.

Exactly the same happens in braid, as used for the outer shielding of 
coaxial cables. Because the lay of the strands is more diagonal, more 
hopping is required so the RF resistance is a little bit higher still.

Now add a thin layer of surface corrosion, which has a much higher 
resistivity than metal. In the solid wire, the current simply pulls back 
into the metal skin beneath, so the RF resistance is almost as low as 
before. But in the stranded wire, the individual strands are forced 
apart and the RF resistance can become a lot higher.

The most dramatic demonstration is what happens when the outer plastic 
jacket of a coaxial cable is cut and rainwater gets in. When the braid 
corrodes, the strands are forced apart and the RF resistance increases 
dramatically. The braid also wicks the water down along the rest of the 
cable run. If this has happened, the only solution is to replace the 
whole length - it's shot.

This effect would be nothing like so severe for my earth mat 
application; but given the choice of solid or stranded wire, it's 
something I'd rather avoid. However, the D10 telephone wire might change 
my mind, because the insulation is extra-strong and would protect the 
wire much better.


>> BTDT - enamelled is a pain to scrape and connect, especially when 
>>doing  it about 200 times, outdoors at ground level.
>
>But surely almost all 'enamelled' wire these days is solderable 
>polyurethane insulated and won't need scraping.


That only applies to 'instrument' wire on small reels. The main source 
of enamelled wire on big reels still tends to be from motor winding 
shops, and they often use a more modern version of the brown enamel 
which is double-coated, temperature-resistant and tough as old boots. 
(But the Dremel trick is duly noted - thank you.)



>
>You can get 6491X PVC insulated conduit wire in solid (single-strand) 
>up to 2.5 mm^2.  (But PVC is a poor dielectric and might also add 
>significant RF loss.)


Thanks for the correction - I'd thought it was all stranded, so that is 
yet another possibility. No problem about the PVC, because the main RF 
losses are in the ground that it's touching.



>>> Or get some  7-strand conduit wire (say 10 or 16 mm^2) and strip out 
>>>the strands.
>> Because of the total length of wire involved, I'm afraid that would 
>>be far too labour-intensive.
>
>YIK, but it did meet the "cheap" part of the specification.
>

I may well do that for the eight "busbar" wires to which all the others 
are soldered. For the other 120 wires, I'd prefer less preparation work 
if at all possible.


-- 
Ian White

"Peter Crosland"  writes:

>> The only fun thing about Walt would be watching him burn to death.
>
>Far too quick and painless.


The bloke's reputation precedes him, apparently.

BTW, uk.radio.amateur is a cesspit. The OP *is* better off asking here.


-- 
       "The road to Paradise is through Intercourse."
        [email me at huge [at] huge [dot] org [dot] uk]

nightjar <nightjar@ wrote:


> or Ormiston Wire (who don't seem to have a web site)


Yes they do - http://www.ormiston-wire.co.uk/ which I mentioned earlier 
in this thread.

-- 
Andy

"Andy Wade"  wrote in message 
news:428fc238$0$24449$da0feed9@news.zen.co.uk...

> nightjar <nightjar@ wrote:
>
>> or Ormiston Wire (who don't seem to have a web site)
>
> Yes they do - http://www.ormiston-wire.co.uk/ which I mentioned earlier in 
> this thread.


That didn't come up when I did a search. Mind you, I stopped using them 
years ago, because they were always the most expensive.

Colin Bignell

Ian

Can I ask as a electronics tech and ex radio amateur (G8HNN) who still has
a real interest in all things aerials, what freq are you using or are they
wide(ish) band ?

Dave

On Sat, 21 May 2005 14:13:39 +0100, Ian White 
wrote:




>A quick Google found Ramco in Skegness selling D10 on eBay at GBP40 for 
>800m (though a friend in the area could no doubt get it for less). 
>Anyone else you know of... a bit closer to PP's GBP10/km mark, maybe?


I've seen it in a number of surplus stores over the last few years -
it is usually in the 1/2mile disposable dispenser packs - a circular
olive green light canvas pack about 2ft in diameter with the wire
feeding out of the centre.  The heavier refillable containers (with
straps around them) are more expensive as military vehicle
enthusiasts like them.

<http://64.233.183.104/search?q=cache:YQshQyvekn4J:www.vmars.org.uk/adspage.html+d10+dispenser+pack.&hl=en&start=1&client=firefox-a>

had someone offering some at GBP10 a pack in March.
-- 
Peter Parry.   
http://www.wpp.ltd.uk/

dave stanton wrote:

>
>Ian
>
>Can I ask as a electronics tech and ex radio amateur (G8HNN) who still has
>a real interest in all things aerials, what freq are you using or are they
>wide(ish) band ?


http://www.w8ji.com/receiving__4-square.htm

Any follow-ups about aerials as such had better be by e-mail, please.


-- 
Ian White

Peter Parry wrote:

>On Sat, 21 May 2005 14:13:39 +0100, Ian White 
>wrote:
>
>
>
>>A quick Google found Ramco in Skegness selling D10 on eBay at GBP40 for
>>800m (though a friend in the area could no doubt get it for less).
>>Anyone else you know of... a bit closer to PP's GBP10/km mark, maybe?
>
>I've seen it in a number of surplus stores over the last few years -
>it is usually in the 1/2mile disposable dispenser packs - a circular
>olive green light canvas pack about 2ft in diameter with the wire
>feeding out of the centre.  The heavier refillable containers (with
>straps around them) are more expensive as military vehicle
>enthusiasts like them.
>
><http://64.233.183.104/search?q=cache:YQshQyvekn4J:www.vmars.org.uk/adsp
>age.html+d10+dispenser+pack.&hl=en&start=1&client=firefox-a>
>
>had someone offering some at GBP10 a pack in March.


Thanks to both Peter and Andy for the specific references - plenty to 
follow up tomorrow.

In fact, thanks again to everybody!


-- 
Ian White

Ian White wrote:


>>> but not enamelled (unless
>>> the price was very, very right)
> 
> 
> BTDT - enamelled is a pain to scrape and connect, especially when doing 
> it about 200 times, outdoors at ground level.


I've never scraped enamel.  On small stuff I use a blue-flame lighter, 
and follow up with a single wipe (not scrub) with emery paper.  Thicker 
wire might need a blowlamp for speed, but the principle is the same.

-- 
Spamtrap in use
To email replace 127.0.0.1 with blueyonder dot co dot uk

Chris Hodges wrote:

>Ian White wrote:
>
>>>> but not enamelled (unless
>>>> the price was very, very right)
>>   BTDT - enamelled is a pain to scrape and connect, especially when 
>>doing  it about 200 times, outdoors at ground level.
>
>I've never scraped enamel.  On small stuff I use a blue-flame lighter, 
>and follow up with a single wipe (not scrub) with emery paper.  Thicker 
>wire might need a blowlamp for speed, but the principle is the same.
>

Those techniques certainly work with polyurethane enamel (typically 
pink/red/green) which is designed to thermally decompose at typical 
soldering temperatures. In doing so, it also acts as a solder flux. But 
as I said earlier, that kind of enamelled wire is available mostly on 
tiddly little reels for lab/workshop use.

The stuff you can buy in kilometre quantities is typically intended for 
motor windings and is brown, double-enamelled, heat resistant and 
extremely tough. Heating to the point of charring still fails to loosen 
it. Completely different ball game, I'm afraid.


-- 
Ian White