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Making your own plastic receiving antenna center dipole peice

Making your own plastic receiving antenna center dipole peice - Chemistry Forum

Making your own plastic receiving antenna center dipole peice - Chemistry Forum. Discuss chemical reactions, chemistry.


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  #1  
Old 02-05-2004, 05:07 PM
Richard
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Default Making your own plastic receiving antenna center dipole peice



Let's say that you wanted to make your own plastic dipole antenna center
peice, by making a mould and pouring into it some chemical.

What plastic materials would be satisfactory?

TIA.

Rich.

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  #2  
Old 02-05-2004, 05:29 PM
Richard
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Default Making your own plastic receiving antenna center dipole peice

Richard wrote:
center

Well, I found this table:

[Only registered users see links. ]

I've read that PTFE is good.

Thing is, this would be a homebrew project, so one has got to be able to
easily get the material and easily work with it.

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  #3  
Old 02-05-2004, 10:22 PM
Steve Turner
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Default Making your own plastic receiving antenna center dipole peice

"Richard" <useless@dot.com> wrote:


It's going to be a bit difficult to "pour" PTFE.


You didn't give many details, but I think I'm familiar with what you
want to do. I would try styrene casting resin.

Steve Turner

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  #4  
Old 02-05-2004, 11:50 PM
HLS
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Default Making your own plastic receiving antenna center dipole peice

Glass center insulators are too easy to come by to spend time on this kind
of a project.

You could pour one out of catalyzed styrene, epoxy, etc, and if you were
even more enthusiastic you could probably make a urethane pour.

You will almost certainly have something that is more prone to fail and more
expensive than you could buy.

Indeed you could buy some pieces of PTFE, nylon, etc and cut one out and you
would be better off.


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  #5  
Old 02-06-2004, 07:18 AM
Repeating Rifle
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Default Making your own plastic receiving antenna center dipole peice

in article [Only registered users see links. ], Steve Turner at
[Only registered users see links. ] wrote on 2/5/04 2:22 PM:


Why not just buy a piece of polystyrene or methylmethacrylate and drill a
few holes?

Bill

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  #6  
Old 02-06-2004, 10:12 AM
Richard
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Default Making your own plastic receiving antenna center dipole peice


"HLS" <Sorry@nospam> wrote in message
news:[Only registered users see links. ]...
kind

I'm wanting to make a center insulator for a VHF antenna made out of
aluminium tubing, so I'm wanting the insulator to clamp tube.

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  #7  
Old 02-06-2004, 10:30 AM
Richard
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Default Making your own plastic receiving antenna center dipole peice

It's for a VHF dipole which will expect to hold together the two halves
of the dipole, which will likely be 3/8" aluminium tubing.

Of course, I could engineer something from block of PTFE or something,
just wondering though about what materials you would use if you wanted
to cast. Just curious.

Whatever one would use, it would have to be simple to do, like pouring
the material into a mold and leaving to set.

So, what folks have said is:

styrene casting resin

catalyzed styrene

epoxy

Whatever, it must be weatherproof and resist UV light.

I don't suppose a trade name comes to mind?

I've got in front of me a commercial dipole center peice from an old TV
antenna. I just call it plastic. It would melt if you put a soldering
iron to it. What would this likely to be made out of? Is this likely a
styrene resin?

Actually, I could ask an antenna manufacturer what they use, but whether
that would be suitable for home casing is another thing.

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  #8  
Old 02-06-2004, 01:16 PM
Eppendorf
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Default Making your own plastic receiving antenna center dipole peice

Maybe use fiberglass? It's pretty easy to work with.

"Richard" <[Only registered users see links. ]> wrote in message
news:bvvp95$10j20q$[Only registered users see links. ].uni-berlin.de...


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  #9  
Old 02-06-2004, 01:17 PM
HLS
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Default Making your own plastic receiving antenna center dipole peice


"Richard" <[Only registered users see links. ]> wrote in message
news:bvvp95$10j20q$[Only registered users see links. ].uni-berlin.de...


Sure...it is clearer now. I don't think you will be able to get the
strength you need nor
the environmental inertness by pouring a catalyzed monomer. The simplest
things to use
are styrene, methylmethacrylate, etc. These are not known for their long
term integrity
where oxidation, UV, temperature swings, gnaw at them.

The ARRL Antenna handbook should have some suggestions for the homebrewer.


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  #10  
Old 02-06-2004, 03:34 PM
Richard
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Default Making your own plastic receiving antenna center dipole peice

HLS wrote:
this
simplest
long
homebrewer.

An antenna manufacturer said that they use high density polythene.

Is that the kind of think you can pour into a mold and leave to set?

Does high density mean it's chippable?



[Only registered users see links. ]

I wonder if there is anything suitable under Products>Castings.

They got Polyester resin:

Clear Casting Resin.

Description: Clear Casting Resin is a water-white, clear casting resin
giving extreme clarity and absence of colour. Properly cured castings
have the same refractive index as glass. Suggested applications include
decorative castings, table tops, objet's d'art, embedding and
encapsulation. Clear Casting Resin AM is orthophthalic, has low
viscosity, low reactivity and low shrinkage. It is set up to cure at
room temperature. The resin is modified with methyl methacrylate to
enhance weather resistance. Uncatalysed resin is aqua blue in colour,
but this clears to water-white when cured.


Polyurethane Resin.

Biresin G26 Urethane Resin.

Description: Polyurethane Fast Casting Resin. Used for the casting of
model kits, figures, foundry tooling and pattern making. Will cast even
the smallest pieces. Very fluid, with an easy mixing ratio (1 : 1) and
very quick setting, producing castings which are highly detailed and
less brittle than those made of polyester resin. For larger castings we
recommend use of a filler, such as Synthetic Onyx. This resin has a 5
minute pot life and a 30 minute cure. Supplied in 2kg packs (1kg resin
and 1kg hardener).
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