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

G0MRF@aol.com G0MRF at aol.com
Wed Aug 5 01:46:10 PDT 2009


 
Hi Lars.
 
Can I suggest:
 
1) A 47k resistor across the input of your converter. The static will have  
a very high impedance and I've found 47k will remove it without increasing  
the noise figure of your converter.
 
2) For really severe cases.  An inductor to ground. An 0805 or smaller  
device. Something that presents a couple of k ohms at the frequency of interest 
 would be OK.  Or perhaps a high pass filter designed for 50 ohms with an  
inductor to ground. Cut off frequency at 30% lower than 23 or 13cms
 
Thanks
 
David
 
 
 
In a message dated 05/08/2009 05:11:17 GMT Standard Time,  
lars.petersen at pobox.com writes:

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






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