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Re: [CQ-Contest] Optical and galvanic isolation

To: "Paul Young" <youngp@hp.com>, <cq-contest@contesting.com>
Subject: Re: [CQ-Contest] Optical and galvanic isolation
From: "Steve Murphy" <murphys@comcast.net>
Date: Tue, 19 Dec 2006 15:07:37 -0500
List-post: <mailto:cq-contest@contesting.com>
Hi Paul,

I don't really see a need for optos unless you've got an unusual situation, for 
instance: a difference in ground potential between your rigs and the switchbox. 
 I did use them at one time in a homebrew SO2R controller, but only because I 
had a bunch and just wanted to do something different, hi.  

IMO, a simple open-collector 2N2222/2N3904 type keying circuit is perfectly 
adequate for modern rigs that use a positive voltage on the keying line.  

Same with the headphones, an isolation transformer is overkill if you're just 
doing A/B switching between two rigs.

Others may have differing experiences, but these methods have been 100% 
reliable for me.  I try to keep things as simple as possible; whenever I try to 
get too cute, it comes back to bite me in the butt.


Steve N8NM
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