Topband: capacity needed for Deturning tower

[John Kaufmann]

On 160 I've used a vertical wire of 20 feet with a 1000 pF variable
capacitor to detune a tower at its base.  You can scale that to 80.

73, John W1FV

-----Original Message-----
From: Topband [mailto:topband-bounces at contesting.com] On Behalf Of terry
burge
Sent: Friday, December 21, 2018 9:22 PM
To: topband at contesting.com; terry burge
Subject: Topband: capacity needed for Deturning tower

Hi again,


This may not be possible to answer with anything like 10% accuracy but can
someone give me an idea just how much capacitance I need for putting up a
50-55' vertical wire up the lower half of my tower to detune it on 75 meters
around the DX windown (3790-3800 Khz). The tower is Rohn 55 with 117' above
ground. A 3 element 20-6 mtr Steppir at 118', a GP6 at the very top with
peak at 134' and a 40 meter dipole (63' or so) at 104'. I have my K8UR style
4-Square around the tower with the lower half of the slopers pulled in
towards the tower. 


Since I've not been able to get a beverage or bog to work due to a lot of
noise I'm going to run a detuning line up to below my Comtek unit at 64' and
try detuning the tower. But I just don't know what to expect to need for
capacitance to detune the tower. 


Terry

KI7M

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