Topband: isolation transformer(s) in RX antenna feedlines (?)

[Tom W8JI]

> My question then is:
>
> 1. Does a multiple sets of grounding blocks for the RG--6 outside the
>    shack hooked to a common point ground hurt anything?

It doesn't hurt anything.  It actually helps everything.

http://www.w8ji.com/images/Grounding/house-entrance.jpg

http://www.w8ji.com/images/W8JI%20site/wirehiderright.jpg

http://www.w8ji.com/images/New%20Contest%20Room/entrance-panel-coax.jpg

> 2. Does a toroid ring on each side of the grounding block with 12 turn
>    pass throughs hurt anything?

A toroid on the antenna side doesn't ever hurt anything and might help. It 
makes the ground less critical. On the shack side of the barrier, the 
particular system should be assessed.

I don't do anything except on four phono cable plug leads and on the BNC 
leads of my K3. Phonos and BNC's are a little prone to having some 
resistance in the shield path as they age, and a sleeve over the shield 
reduces common mode that might couple in at the connector.

When I've had switching supply noise, the BNC's and phonos have generally 
been the way the noise has gotten in. Wiggling the changes the level when 
they act up, just like it does on a bad F connector shield connection.

For the most part, my cables from entrance to desk are routed in group to 
keep the "RF loop" through the equipment closed.

http://www.w8ji.com/images/Shack/house-desk.jpg

A sleeve over coax or winding around a core is far less problematic than 
breaking the shield. It isn't so much that breaking the shield is bad, it is 
just how it is physically accomplished that can be the problem.

Also, all cables should go through a bulkhead. At the house, I have two 
bulkheads. One outside the wall for lighting and so I can move cables 
around, and a bulkhead in a wire hider where cables enter the room. The wire 
hider contains all the shack AC power line sources, all control cables, all 
RF cables, and all RF switching.

The last thing I want is a conductor entering the room that isn't common to 
the room entrance ground.

73 Tom