[hpsdr] ALEX - Input protection

[Ray Anderson]

> All:
> I am looking for ideas for input protection for ALEX.
> 
> Lyle has recommended a gas-discharge tube device, which I will use
> on any port that could be hooked to an antenna to limit large voltage
> surges. (Digikey 495-1475-ND)
> 
> But, I have a concern, that the gas-discharge tube limits in 
> the 70 volt
> range, and the Hittite electronic switches and electronic attenuators
> on Mercury will probably break down at lower voltages, I am
> guessing in the 25 volt range.
> 
> Frank Carcia has recommended using low capacitance diodes
> (1N4148 or similar) biased at around +/- 10 volts, so that they would
> clamp the input at that voltage.
> 
> Does anyone else have any other ideas that they would suggest?
> 
> I am looking for something that would present a fairly low capacitive
> load to the input lines, and clamp at a voltage that must be 
> higher than
> about +/- 2.5 volts, but lower than +/- 12 volts.
> 
> Thanks,
> --- Graham / KE9H
> 
> ==
> 

Graham-

Also see the following message posted in March 2007 on the subject by
Achim, DH2VA.  

http://lists.hpsdr.org/htdig.cgi/hpsdr-hpsdr.org/2007-March/003847.html



-Ray   WB6TPU


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