[HBR] Riddle me this!

[Gary Pewitt]

I've found that the brownish plastic bottles that prescription medicines 
come in work fine.  They come in many sizes and you can request the 
pharmacist to put your pills or capsules into the bigger size bottles 
even if they would fit the little ones.  I've accumulated many of them 
and doubt I'll ever run out.  It's not difficult to fit them to an old 
tube base for plug in coils.  73  Gary  N9ZSV


On 11/28/2014 01:00 PM, Brian Burns wrote:
> 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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