R.Measures wrote:
>On Apr 13, 2005, at 5:06 PM, Bob Maser wrote:
>
>
>
>>McMaster/Carr sells electrical grade PTFE 1-1/2" rod for $35.04 per
>>foot. I
>>don't call that expensive.
>>
>>
>
>Plastifab (818 967 9376) carries various diameters of G-10 tubing.
>0.75" dia goes for around $1.20 a foot. G-10 is RF-friendly, does not
>cold-flow like TFE, and it is easy to fabricate.
><snip>
>
>
I agree with Rich that fiberglass tube is by far the least costly
material and is commonly available. It may come down to a matter of
comparing the minimum order from your supplier with the cost of a foot
of PTFE. With the PTFE you only need to drill and tap a hole in the end
of the rod to mount it and you can drill small holes for brass screws or
pins to attach the wires. With fiberglass tube you'll still have to
come up with a mounting for the tube.
McMaster-Carr <http://mcmaster.com> lists Fiberglass tube and G-10 tube
separately and at dramatically different prices. Using 1" OD virgin PTFE
rod to compare with the 1" OD tube at McMaster, here is what I found:
1" OD PTFE solid rod, dielectric strength 500 V/mil: $16.79 per foot.
(page 3338)
1" OD Fiberglass tube (glass fiber-reinforced polyester), dielectric
strength 200 V/mil: $2.27 per foot (5 ft length @ $11.34 minimum order)
(page 3345)
1" OD G-10 Garolite (glass-cloth laminate with epoxy resin), dielectric
strength 300 V/mil: $13.71 per foot (39" length @ $44.55 minimum order)
(page 3352)
Any of these will work fine for the RF choke.
McMaster gets high marks with me. They warehouse locally, keep a good
stock and I get 24 hour delivery on a phone or Internet order.
73, Tony W4ZT
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