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[AMPS] coil form plastics

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Subject: [AMPS] coil form plastics
From: (
Date: Mon, 15 Feb 1999 13:17:40 -0500

On Mon, 15 Feb 1999 00:18:09 +0000 "Ian White, G3SEK"
<> writes:
>Carl wrote:
>>On Sun, 14 Feb 1999 11:28:09 +0000 "Ian White, G3SEK"
>><> writes:
>>>In the end, the only way to find out is to try it. For situations 
>>>an inexpensive and easily machined material such as Delrin is proved 
>>>work, there's no point in paying for PTFE or ceramic.
>>B&W initially used ceramic forms for their 802 plate RFC. As a cost
>>reduction they went to Delrin. I have several failed Delrin RFC's 
>>that all failed at the tube end only which makes me believe it was a 
>>related failure, not DC or straight IR losses. 
>Fair enough - anything involving high RF potentials (and probably 
>temperatures too) is a risky application that would need careful 
>before committing to production. It's more difficult for component
>manufacturers such as B&W and the roller coil makers because they 
>anticipate all future uses. 
>It then comes back to the equipment manufacturers to test their 
>well beyond the claimed ratings... but then the marketing droids want 
>market the products at the test ratings! Finally the end users push 
>products harder still, and sure enough, they fail.
>>Soft Teflon makes a poor choke form but hard Teflon works quite well. 
>>believe it has a fiberglass mixture. Machines well and costs less 
>>pure Teflon.
>Any brand names and sources?


IPM is one mfg and available locally from Plastics Supply Corp which I
believe is USA wide. 
There are probably several others that stock but today is a holiday and
I've been unable to get more info sofar. Perhaps others have additional
The correct nomenclature is " glass filled Teflon".

73  Carl  KM1H

>73 from Ian G3SEK          Editor, 'The VHF/UHF DX Book'
>                          'In Practice' columnist for RadCom (RSGB)
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