[HBR] Riddle me this!

[Ron Barlow via HBR]

The link that you provided didn't function for me.
 The numbers that you listed appear to refer to the dielectric constants of the materials, not for dielectric losses. For the latter, you should look at "dissipation factor". Use a search engine for further info.
                    GL & 73 de Ron
--------------------------------------------
On Fri, 11/28/14, Brian Burns <brian at lessonsinlutherie.com> wrote:

 Subject: [HBR] Riddle me this!
 To: "'HBR Receiver List'" <hbr at mailman.qth.net>
 Date: Friday, November 28, 2014, 2:00 PM
 
 Hello All,
 
  
 
 My thoughts have turned to plug-in coils, for no particular
 reason except
 that I'm likely to need a bunch of them if I want to cover
 all the bands.
 Being an inveterate "do-it-myselfer", I'm looking into
 making my own---you
 can see that it's going to be a while before I'm able to
 listen to 40 meter
 CW (;->).
 
  
 
 So I'm curious about the dielectric properties of the
 various materials that
 I might use for making the forms. I go to good-ol google,
 and search on
 dielectric properties of polypropylene, a likely suspect,
 and up comes the
 following link:
 
  
 
 http://www.rfcafe.com/references/electrical/dielectric-constants-strengths.h
 tm
 
  
 
 For best selectivity and highest gain we would like our RF
 amplifier and
 mixer plug-ins to be high Q (right?). Air is the best core
 material to get
 the highest Q, but it's a bit deficient in mechanical
 properties. We need a
 form to wind our coils on, and wouldn't it be grand to be
 able to just order
 up some ceramic (probably steatite) coil forms like the
 old-timers used. So
 if Air is the best, and higher numbers are worse:
 
  
 
 Air............1.000
 
  
 
 Steatite..........5.3-6.5
 
  
 
 Bakelite..........3.7
 
  
 
 
 Polypropylene.........2.2
 
  
 
 Douglas Fir...........1.9
 
  
 
 Wood............1-2
 
  
 
 Wood!?? You gotta be kidding! Much as I love to work wood,
 I'll stick to
 polypropylene as a more practical material. But, never more
 will I lust
 after ceramic coil forms---or am I missing something here?
 
  
 
 Cheers,
 
  
 
 Brian
 
  
 
     
 
  
 
  
 
 
 
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