Topband: Dual band shunt-feeding tower on 160/80

[Herb Schoenbohm]

Jeff,  You will have problems with attempting to shunt feed a 100 foot 
grounded tower on 80 since it approaches a grounded half wave radiator 
and just to long on 80. The solution for this is to make a decoupling 
sleeve on the tower by elevating the 80 meter feed up the tower  and 
bring down several skirt wires at the 40 foot level that are a least a 
1/4 wave long on 80.  You can bring them to the ground and run the extra 
lengths out parallel and insulated from the ground.  This will allow you 
to shunt feet above the skirt attachment point. The only problem with 
this is that it will impact the 160 mete feed and you may have to have a 
HV switch to disconnect the unused band.  So report that just connecting 
the 80 meter coax braid up the tower and fanning out some radials at 
that point can work. But again why screw up a perfectly good 160 meter 
vertical when you can hang 80 meter slopers from it with less impact and 
not so much hassle?


Herb Schoenbohm, KV4FZ





On 8/25/2013 11:43 PM, Jeff Blaine wrote:
> A buddy of mine has a 100’ 25G tower and wants to run it on both 160/80.  I’m thinking a par of shunts will work for that?
>
> If you have done this, I would be interested in your comments on the general implementation.
>
> Thanks!
>
> 73/jeff/ac0c
> www.ac0c.com
> alpha-charlie-zero-charlie
>
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