Fw: Re: [HBR] PVC coil forms for the W6TC HBR

[Kees & Sandy]

I performed a number of experiments measuring the effect of coil form material, coil dope, wire spacing, winding method, etc on coil "Q" some time ago. It's at the end of the section on "Q Meters" on my web site ....just follow the link at the end of this message.   qsl.net/k5bcq 
Regular schedule 40 PVC was really pretty good. If you have access to a lathe you can turn the ends to perfectly fit old tube sockets and trimmer capacitors, even put rings on the ends.
73 Kees K5BCQ

-- "amargosaent at iscweb.com" <amargosaent at iscweb.com> wrote:
Does anyone on the reflector have first-hand experience with, or direct 
knowledge of, the performance of PVC tubing with a typical 0.066-in wall 
thickness in an HF receiver front end application as typified by the 
Crosby HBR?  Floating around in various places on the net there is some 
vague commentary about general unsuitability of PVC for coil forms due 
to "excessive losses".  No specifics are cited, nor linkage to sources, 
and as a result it is then impossible for me to decide if the commentary 
is rumor, speculation, or has some measure of substance.

The reason for the query is my intent to move forward (or perhaps not) 
with some experimental work on HBR coil forms using PVC NMT (non 
metallic electrical tubing) and PVC Schedule 40 pipe parts.  I have a 
preliminary physical design using a standard PVC pipe connector, plus a 
5-pin connector customized from a PVC pipe cap, and a coil winding 
surface using the NMT.  Stability of the physical design looks 
promising, but I would prefer not to waste time on coil experiments if 
there is significant truth to the "PVC excessive loss" story.

My in-house references, texts and ARRL handbooks do not shed useful 
light on the subject.

Any thoughts, anyone?

73 de W6HHT
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