[HBR] Dissipation factor of materials

[James Fuller]

Hi Brian,

Most of the tubular items, extension pieces, tail pieces, p traps, etc are made from polystyrene.  They are all no pressure items and are not used for pressure.  PVC drainage on the other hand is made of PVC and is not as suitable for coil forms.  

JamesF



On Nov 29, 2014, at 9:35 AM, Brian Burns <brianburns1066 at gmail.com> wrote:

Hello James,

~ I'm sure that most of you know this but if not, lowe's and other big box
stores sell 1-1/2" od polystyrene extension pieces that are 16" long and
have small flanges on both ends.  They are also available in 1-1/4" OD but
not as commonly.  They also sell 3" polystyrene couplings that fit over 3"
nominal sewer pipe. The couplings are about 3-5/8" OD from memory and make
great forms if you need a large coil.
JamesF

If these are plumbing parts they are probably PVC, polyvinylchloride.
Polystyrene has great RF properties, but its thermal and mechanical
properties are not very good.

Cheers,

Brian 







>> On Nov 28, 2014, at 2:42 PM, "Brian Burns" <brian at lessonsinlutherie.com>
> wrote:
> 
> Hello All,
> 
> 
> 
> Here are some numbers I found for dissipation factor:
> 
> 
> 
> Polystyrene-------------------------------------------.0002 to .00007
> 
> 
> 
> PVC------------------------------------------------------.016
> 
> 
> 
> Steatite--------------------------------------------------.0035 to 
> .0008
> 
> 
> 
> It would appear from these that polystyrene is quite a bit better than 
> even steatite ceramic, probably what was used in old-timey coil forms. 
> No wonder it was so well liked for UHF stuff at Hansen Labs, where I 
> used to work back in the day. Not only does it melt easily, it crazes 
> over time. The base that I have in mind is available from National, 
> and shouldn't have the melting problem, as it's ceramic.
> 
> 
> 
> Next question: Does using the lowest loss coil form "make enough 
> difference to make a difference"? Walt's experience, as well as other 
> builders', using PVC seems to say "no it doesn't".
> 
> 
> 
> Cheers,
> 
> 
> 
> Brian
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
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