Topband: Topband Tower Antenna With Two meter Vertical

[Herb Schoenbohm]

Remember if you run a three or four wire cage to the top of the tower it 
is the cage, not the tower, that does most of the radiation.  This I 
would think makes running cable inside the tower not important.  
Additionally, with crank ups running cables inside a tower can be a real 
mess.  On crank up cables need some sort of offset.  OK, just make a 
cage that is space much farther away from the tower than the drop wires 
and coax.  This should be better than having  your coax and rotor cables 
chewed up when you do the crank down procedures at night with an 
approaching storm.


Herb, KV4FZ





On 4/15/2012 2:01 PM, W0MU Mike Fatchett wrote:
> I heard that there is a reason to run the coax on the outside of the
> table as running it inside can create some issues.  I just don't recall
> what it might have been or if the warning was based on fact or just
> anecdotal comments.
>
> Mike W0MU
>
> W0MU-1 CC Cluster w0mu.net
>
>
> On 4/15/2012 10:28 AM, Jim Brown wrote:
>> On 4/15/2012 8:49 AM, Wayne Rogers wrote:
>>> Also - on the antenna installation.  Typically the two meter vertical's outer conductor will be grounded to the tower at the base of the two meter antenna.  I could also keep the two meter antenna insulted from the tower for its entire length up to the lightning protector just before it enters the house.  What's the recommended practice?  Ideas?
>> First, always run rotor cables and coax for antennas mounted to the
>> tower INSIDE the tower. This allows skin effect to minimize 160M current
>> on those cables.  Second, proper bonding of the coax shield to the tower
>> top and bottom is good practice for lightning.  Third, coming away from
>> the base of the tower, wind as many turns as you can of each cable
>> through at least one #31 toroid.  This prevents these cables from
>> becoming part of the radial system.
>>
>> Ferrite beads clamped onto a cable are next to useless on the HF bands
>> because they are inductive, not resistive, so all they do is TUNE the
>> cable to which they are attached.
>>
>> If the tower is very close to the house, it should be bonded to the
>> combination of all grounds in the house, which, MUST be bonded
>> together.  That includes power entry, telephone entrance, cable TV,
>> satellite dish, ham shack, etc. If the tower is distant from the house,
>> only the cables coming from the tower should be bonded, not the tower
>> itself.
>>
>> 73, Jim Brown K9YC
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