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Re: LF: Vertical antenna and connection line

To: <[email protected]>
Subject: Re: LF: Vertical antenna and connection line
From: "Fausto Coletti" <[email protected]>
Date: Thu, 6 Jan 2011 14:19:32 +0100
In-reply-to: <[email protected]>
References: <[email protected]> <[email protected]>
Reply-to: [email protected]
Sender: [email protected]
Thanks you Rik and Stefan for answer,
 
of course I connect one wire of the ladder line at the ground just under the antenna and the same wire to the "cold" end of the variometer,
the other wire frome the antenna and the "hot" end of the variometer.
I have think to cross the wall of the house through two copper tubes connectef to ground then pass the two wire
at the center of the tubes.
Another idea would to be use two coax cable with center conductor as parallel line and the shields grounded.
Yesterday i have finished the tx converter, i have used a very stable OCXO (0.05 PPM) at 6.4 MHz (i had this),
anHPF505 mixer and two transistor amplifier stage for driving a TDA2030. I have obtained about 5 Watt of RF
at the output of the low pass filter and a decent harmonic suppression. With this i want to drive a linear amplifier
with four IRFP540 (G0MRF schematic). I hope to obtain 250-300 Watts but for CW operation i think to build a Kilowatt class D amplifier.
For ground quality question i have no measurement data at the moment.
I live in the country and around i have only cultivated land for several hundreds of meters, i think that can have a good conductivity
The garden where i  have installed the tower is about 55 x 30 meters and I'm installing 120 or more buried radials, 15 to 35 meter long 
as 160 m ground plane (the 25 meter tower), you can see the photo at QRZ.com. the shack is in the corner of the house close to my car.
 
73 Fausto IK4NMF
----- Original Message -----
Sent: Thursday, January 06, 2011 12:51 PM
Subject: Re: LF: Vertical antenna and connection line

Fausto,

You can do that but you should place the ladder line between ground and the "cold" end of the main coil. Otherwise you'll have several kV in the shack and lower the radiation resistance strongly! Instead of ladder line you could use coax cable as well, although it has much more C per meter.
You even can add a galvanic decoupled primary winding on the coil and feed the RF through a coax cable such as RG213. Then you can fine tune the system (e.g. for QSY within the band) in the shack, at a lower impedance!

Do you already have some data like the ground resistance and/or your planned TX power? :-)

73, Stefan

Am 06.01.2011 12:28, schrieb Fausto Coletti:
Hello,
A question for RF expert:
you think that i can connect a Marconi antenna and relative gound system to the variometer with a high impedance ladder line?
This because i need to have all the tuning equipment indoor and the tower that support the vertical part
of the antenna is about at 20 meters to the home.
 
Thanks in advance for answer
 
Fausto IK4NMF

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