On Apr 14, 2005, at 7:15 AM, Tony King - W4ZT wrote:
> 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.
I epoxy the tube to a square of flat G-10 that I notch with an
adjustable circle-cutter and a drill.
>
> 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.
... and high prices 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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>
Rich Measures, 805.386.3734, AG6K, www.somis.org
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