On 02/24/2013 05:30 PM, ceo@...
> You want to steer clear of PET ABS and PVC...
> Table of loss tangents:
> Polystyrene 0.0001 (recycle #6)
> LDPE 0.00012 (recycle #4)
> HDPE 0.0002 (recycle #2)
> PTFE (Teflon) 0.00025
> Polypropylene (PP) (recycle #5) 0.0002 - 0.0005
> PET 0.014 (recycle #1)
> ABS 0.02
> PVC 0.023 (recycle #3)
> Could you do some Q measurements on it, then try another
> one with polypropylene pipe instead? It would interesting
> to see if there is a major difference in Q factor.
> I think one of the reasons the FSL's do so well is the
> construction technique - that foam stuff everyone uses
> between the ferrites and the coil has a nice low loss
But using a tube of plastic as a coil form is not making a
tuning capacitor with these plastics as the dielectric. It
is not even between the turns, but only beside them.
The plastic makes up only a fraction of the total dielectric
involved in the coil parallel capacitance.
So the plastic losses might not be so significant as these