[Amps] Chimney Construction

[Steve Thompson]

On Sunday 14 September 2003 15:26, ARNE GJERNING wrote:
snip
> 3.  Make from sheet and secure with NYLON screws and nuts.

I've always been dubious of nylon in high rf fields, although I couldn't give 
examples of why.
>
> 4.  Make from sheet and use ordinary brown plastic (mylar?) parcel tape
> gives good
> results. W2GN made hundreds of these for the ARCOS VHF amps.
>
> Use the tube anode as a former, and wrap the teflon sheet around it to
> make about a half-inch overlap. Then tape crosswise over the joint with
> a one-inch wide strip of parcel tape, wrapping it over the inside of the
> chimney too. (I hope that's clear: the tape doesn't go around the tube,
> it goes around the overlap in the teflon sheet.)

A variation occured to me but i have never tried it. Wind the chimney as 
described, then drill some small holes in the overlap area and use something 
to stitch the pieces together, like sewing - I had thought to use the outer 
from PTFE covered wire, but many other things might work.

Steve