[BC] Wireless Internet Installation on AM Tower

[Cowboy]

On Wednesday 08 July 2009 01:20 am, Milton R. Holladay Jr. wrote:
>  Dana and Mark's seems like the best idea to me.
>  If it can't be done this way, the next best thing would be a shorted 1/4
>  wave isolation section (called a bazooka by some). As a conduit for shielded
>  cat 5, there should be 1/2'' or larger copper tubing on insulators going up
>  the inside of the tower a bit past the calculated 1/4 wave point and,
>  ideally, the exact point for the short found by probing while measuring the
>  tower Z so as to set it where the resistance is the same as before. The
>  reactance will change some, so the taps of the output coil will need
>  adjusting a bit to get the network input back to 50R j0. If not 1/4 wave
>  tall, oh well..................
>  M

 All things considered, this bazooka design, and Richard's suggestions,
 make the most sense to me. Biggest bang for the buck, BUT the
 critical question remains. Is this a DA, or Non-D ?

 I would not use shielded CAT wire in any case, as shields are usually
 a bad idea. They tend to prevent you from addressing the real problems,
 unless ( as in this bazooka ) the shield ( conduit ) is actually part of
 the design solution. The shield suggested wouldn't be, and would be
 isolated from being addressed by the jacket.
 I'm pretty sure I wouldn't go the expense of copper conduit, but would
 look at both rigid, and EMT depending on the expected life of this
 tower modification above the base insulator.

 As Milton suggests, if this stick is not 90 degrees or more, this also
 complicates a bazooka, as the bazooka will need to be run all the way
 to the top, and then the CAT run back down the stick to the mount
 point for the equipment, and further throw off the Z of the stick.

 I don't like the fiber, or the choke suggestions, for the cost and
 future maintainability.

 Of course, we don't yet know if this is a grounded skirt fed tower, in
 which case all of this complexity goes away, though he's still left
 with the re-tune.

-- 
Cowboy