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[TowerTalk] receiver protection

To: towertalk@contesting.com
Subject: [TowerTalk] receiver protection
From: Pete Smith <n4zr@contesting.com>
Date: Mon, 28 Mar 2005 16:16:36 -0500
List-post: <mailto:towertalk@contesting.com>
I am looking at a design for receiver protection in an SO2R environment 
that involves a series resistance (#49 bulb) and stacks of back to back 
diodes shunting the receiver input.  The objective is to protect front-end 
components against strong out-of-band signals, but in the process I don't 
want to incur an intermod penalty under normal operation.

If I stack 3 diodes in each direction, the forward conduction point will be 
2.1 volts.  Is that high enough to avoid generating intermodulation, except 
under circumstances where I wouldn't be able to hear anything anyway?  I 
figure that much voltage at a 50-ohm receiver input terminal to be 
something like S9+80dB.

Thanks for your advice.

73, Pete N4ZR
The World HF Contest Station Database
was updated 16 March 2005
2925 contest stations at
www.pvrc.org/WCSD/WCSDsearch.htm  

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