[AMPS] RF Choke Forms

[dan hearn]

The handbook "Reference Data For Engineers"  by ITT, has a table showing
D factor loss for many plastic and ceramic materials for frequencies
between 60 hz and the microwave range in 6 steps. It also has voltage
breakdown, volume resistivity, thermal softening point,thermal
expansion, and dielectric constant (should be low for RFC forms). I was
surprised to find that Teflon has lower D and K than Steatite 410. I do
not see Delrin in the table but am pretty sure it is inferior to Teflon.
This HB is an old one, 1975.

73, Dan, N5AR 

Arne Gjerning wrote:
> 
> I have been advised NOT to use Teflon, Delryn, and a few other
> insulating materials for an RF choke. Instead only use ceramic. It was
> then stated the "D" factor was the reason.
> 
> OK, but why as I could not find info on this subject in the ARRL
> Handbook. Any help to point me in the direction of knowledge on this
> subject would be appreciated.  May as well learn something while
> building my amp. And I want to do it RIGHT.
> 
> 73 de Arne N7KA

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