Topband: RX antenna switching - multi-rig, multi antenna

[Tom W8JI]

For my system here, I have a multicoupler board already laid out that can be 
used for any number of antenna systems into four receivers. Because these 
are proto boards, they are a little pricey. They are a low quantity board.

Each antenna channel has about 6 dB loss from in to out for any receiver, so 
you would have to consider that. The advantages are it is passive magic T's, 
so it generates no measureable IMD. You can bridge all four receivers to one 
antenna, or to any antenna, independently. You never notice another receiver 
coming on line with existing receivers.

It can also be built out to bridge more than 4 receivers to any number of 
antennas.

In my system I amplify and equalize levels on all antennas, so I have TX 
antenna attenuated plus any number of RX antennas available.  I have seven 
RX antenna ports in right now plus TX antenna.  The three large Europe RX 
antennas are on dedicated ports, and the other four systems switch 
directions with a small control box.

It picks any of these antennas:
http://www.w8ji.com/images/W8JI%20site/w8jiantennas1S.jpg

 73 Tom




----- Original Message ----- 
From: "Jeff AC0C" <keepwalking188 at ac0c.com>
To: "Tom W8JI" <w8ji at w8ji.com>; "Art Snapper" <art at nk8x.net>
Cc: "160" <topband at contesting.com>
Sent: Monday, April 20, 2015 11:58 PM
Subject: Topband: RX antenna switching - multi-rig, multi antenna


> Art,s question has got me thinking about how the big multi-multi handle a 
> bunch of receiving antennas routed to a bunch of stations?
>
> Here I'm looking at up to 8 rx antennas fed to 4 stations.  But the more 
> you dig into this, the more complicated it can get.  A crossbar-sort of 
> switching arrangement would do the signal routing - but it would not 
> provide any rig to rig isolation and would not maintain a constant Z 
> (important if the rx amp is a norton type).
>
> 73/jeff/ac0c
> www.ac0c.com
> alpha-charlie-zero-charlie
>
>
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