Re: Thai Score


Everett N4CY
 

All PE, polyethylene foam, is basically the same. Some is open cell and some 
is closed cell. The cell size determines the density, the listed density is in pounds 
per cubic. In some cases PE foam is cross linked with other materials that are added to improve the strength. 

Everett N4CY


On Mar 8, 2016, at 12:36 PM, dx@... [ultralightdx] <ultralightdx@...> wrote:

 

I believe I've read it in a crystal radio enthusiasts forum, but it's my understanding that the "Dissipation Factor" of various plastics, foam, (or other materials) is what makes the difference. A very low dissipation factor is desirable.


Check out this list of "Electrical Properties of Plastics": Electrical Properties of Plastics

 

73, 
Guy Atkins
Puyallup, WA



---In ultralightdx@..., wrote :

Any idea why some foam results in poorer performance?
Last year I tried a "knock-up" with old hotel-radio
ferrites, good litz (with and without a silver-plated
air-spaced variable C) and whatever was to hand. So maybe
the UK-sourced foam was part of the reason for disappointment.
Could it be that some foam has metallic content?
To try again, I would have to try foam from different
sources on a hit-and-miss basis. As LW and MW is dying
in Europe, I am reticent to risk too much outlay and will
probably return to a longer single ferrite rod and/or
1meter dia frame loop

Michael

On 04.03.16 23:50, D1028Gary@... [ultralightdx] wrote:

> <<< I am in the process of gathering materials to build the 3 " FSL
> antenna, I am just wondering where you can buy the Oatey 4x4 foam closet
> spacers? >>>
> The Oatey 4" foam spacer material is sold at Home Depot stores within
> the USA, and is located in the plumbing section of such stores. It is
> extremely cheap, with a full roll of the material (good enough for 2 or
> 3 antenna jobs) costing just over $1.
> Because this material is so cheap and because it is actually quite
> important for proper FSL coil sensitivity, substitutions are not
> recommended. Already one DXer did a very good job in constructing his 3"
> FSL PL-380 model but used a different type of foam, and ended up with
> seriously reduced MW sensitivity as a result.
 

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