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Topband: Use of the RCS-4 for Remote Beverages?

To: <topband@contesting.com>
Subject: Topband: Use of the RCS-4 for Remote Beverages?
From: W8JI@contesting.com (Tom Rauch)
Date: Wed, 23 Oct 2002 08:53:30 -0400
> Part of my idea is to run coax out to the center of the field, and
> then use an Ameritron RCS-4 remote switch as the center hub. 

The newer version of the RCS-4 should be better at switching receive- 
only signals. It now uses fully sealed relays which are more immune 
to contact contamination. 

The older open-frame relays were OK if you transmitted through them 
on occasion, but probably are not a good idea in receive only 
application. The new boxes have the connectors in a rectangular 
layout, rather than in a line.

Just be sure you have good clean dry coaxial cable connections 
between the controller and the switch. 99% of the problems are from 
poor or wet cable connections to the box. 
 
> I am also considering putting one 9:1 xmfr inside the RCS-4 and 
> then just running the each Beverage wire into each of the four
> antenna jacks ... thoughts on this ? (4 wires, 4 directions, etc. ...)

The following is true for almost any 160 meter switching system.  

I would not put the transformer on the input. The primary mode of 
unwanted coupling to unused ports is through capacitance. That means 
port isolation of the switch increases as the impedance is reduced, 
and unwanted port "leakage" increases quite rapidly as impedance is 
increased.

Not only that, you would be running high Z leads to the switch, and 
also have a common ground for ALL Beverages. Very bad news for 
performance.

Use transformers at each antenna, use isolated primary and secondary 
windings in the transformers, and use separate ground rods on each 
antenna. The ground rods don't need to be exceptionally deep or good 
at the feedpoint end, as long as you use an isolated winding 
transformer.

73, Tom W8JI
W8JI@contesting.com 


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