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Re: [Amps] Teflon Chimneys

To: amps@contesting.com
Subject: Re: [Amps] Teflon Chimneys
From: Ian White GM3SEK <gm3sek@ifwtech.co.uk>
Reply-to: Ian White GM3SEK <gm3sek@ifwtech.co.uk>
Date: Sat, 14 May 2011 12:04:15 +0100
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Robert Briggs wrote:
>
>Hi all...I have been thinking of ways to make Teflon Chimneys for GS-31
>and 35B tubes from 1mm sheet...I am finishing off a 2 meter and a 70cm
>amplifier at present and would like some opinions...
>
>The simplest solution looks to me as making the Teflon tube and
>fastening the join length with brass eylets perhaps one eylet per inch....
>
>My concern is would the small eyelets be subject to RF heating and
>perhaps burning the Teflon sheet at the join??
>

W2GN had very good results with brown mylar parcel tape In his ARCOS 
series of VHF/UHF amplifier kits (2 x 4CX250R/8930). The chimneys in my 
ARCOS K2RIW survived 20 years of very hot air.

The method is shown in Figure 20 of 
<http://www.newsvhf.com/2m_stripline.pdf>  In that description W2GN 
suggests using PTFE plumber's tape but in his kits he used the parcel 
tape which is much simpler. One turn will do it, overlapped on the 
outside.



-- 

73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek
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