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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