Topband: Rotator Potentiometer shunt fed twr
Jim Brown
jim at audiosystemsgroup.com
Sun Aug 23 17:04:05 EDT 2020
On 8/23/2020 12:39 PM, dj7ww at t-online.de wrote:
> Bypass the rotor with thick ground lead from the rotating pipe mast to the
> tower
Yes. This solves other issues.
use ceramic bypass capacitors on the pot contacts and MOVs or low
> voltage spark gaps to ground on all lines to the rotor and controller.
MOVs are a very bad idea, and I see no benefit from the caps.
> Use screened rotor cable, with the screen grounded to the tower at top and
> bottom.
I don't see the need for this.
If the rotator cable is laced to the tower (most prefer the inside of a
tower leg) it will be at the same potential as the tower all the way
along the height, thanks to capacitance between the cable(s) and the
tower. Remember, this is RF, not DC, and the current we're talking about
is antenna current, which is near a maximum at the base an minimum at
the ends of the elements of the Yagi(s) that serve as top loading.
73, Jim K9YC
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