[Amps] Teflon Chimneys

[Ian White GM3SEK]

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