[amsat-bb] Re: Avoiding statics on helix antennas

[Joe]

don't forget the velocity factor too!

My first thought was to try to find out where the static is coming from 
in the firstplace and fix that. Why put a band-aid on a cut when you 
prevent the cut in the first place?
Joe WB9SBD

i8cvs wrote:

>Hi Lars, OZ1BXM
>
>The shorted quarter-wave coax line suggested in the ARRL Handbook 2008 and
>2009 pages 23.20-21 will work great because it is a short circuit for the
>static electricity and a theoretically infinite impedance at the resonant
>frequency so that for the RF input signal it is completely ignored by the
>input stage of a converter or preamplifier.
>
>Remember that a quarter-wave transmission line when shorted at one end
>shows an infinite impedance in theory at the open end as you can see using
>the Smith Chart.
>
>If you enlarge a shorted quarter-wave by any even or odd number of  1/2
>wavelenght of coax line thing do not changes because a 1/2 wavelenght of
>transmission line represents a full turn of the Smith Chart.
>
>Do it as suggested by the Handbook !
>
>73" de
>
>i8CVS Domenico
>
>----- Original Message -----
>From: "Lars Petersen" <lars.petersen at pobox.com>
>To: <AMSAT-BB at amsat.org>
>Sent: Tuesday, August 04, 2009 6:01 PM
>Subject: [amsat-bb] Avoiding statics on helix antennas
>
>
>  
>
>>Hello AMSAT list,
>>
>>I have a problem caused by static electricity building up on my two helix
>>antennas (23 cm and 13 cm). Two converters have already been zapped, so I
>>have to do something about it.
>>
>>What measure would you recommend to avaoid statics building up on helix
>>antennas?
>>
>>Does anyone have experience using the shorted quarter-wave-stub mentioned
>>    
>>
>in
>  
>
>>"The ARRL Handbook 2008" pages 23.20-21?
>>
>>Vy 73, Lars Petersen, OZ1BXM,
>>AMSAT-Member 36222,
>>oz1bxm at pobox.com
>>www.oz1bxm.dk
>>
>>_______________________________________________
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>>
>
>
>
>
>
>
>_______________________________________________
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