Ladder line will offer little benefit is this kind of setup. Once you ground
one side of it, it isnt even ladder line anymore, but is a single wire
hookup to the long wire. Running the odd side of the ladder line to ground
thru a gas arc makes little sense, since if you are gong to ground the wire
in that side of the line, you may as well ground it directly and just get it
over with. It is the LIVE side that would need to go thru the gas arc, if
you were going to actually implement this setup.

The actual impedance of the long wire will vary with both the length of the
wire, and the frequency it is being operated on. Effforts at "matching" this
setup thru a "transformer" would assume its impedance will remain more or
less constant , which , as I just got done saying, is not the case. You will
get no "transformer" activity here with one side of the ladder line grounded
anyway.

The reasoning behind your statements concerning "common-mode noise" and
coaxial cable escape me. There really is no such thing as "common-mode
noise" on a coax cable. either the shield is grounded , or it is not, in
which case , the shield does not shield the inner conductor, which is where
the radio takes the signal off the coax. It is the center conducter that
picks up noise and feeds it to the radio. This is usually due to either the
shield of the coax not being grounded or the chassis of the rig not being
grounded (which usually accomplishes the shield ground anyway on most rigs).
This lets the noise into the coax so that it can get onto the center
conducter in the first place. You most certainly would not use things like
gas arc supressors in these grounds, since you want a constant connection to
ground on these, rather than one that only operates when a high voltage
spike appears. Gas arc and gap type supressors are used on parts of the
system that are NOT normally directly grounded, like the center conductor of
the coax. If a lightning spike appears on the center conductor, then the gas
arc or gap will "activate" and feed it to ground, which is the plan here.
The rest of the time, the gas arc or gap type supressor is electrically
open.


"mike" wrote in message
...
Given I am currently using 75 ohm coax to feed my random wire, I
believe I could use a 300 ohm to 75 ohm (4:1) TV twin lead to coax
converter and get away with it.

Please correct me if I am wrong, but I think I would attach the random
wire to one terminal of the 300 ohm input. The other would go directly
to earth ground, or via a gas arc tube to ground.

On the other side, I would attach my coax cable.

To give the coax feeder a ground at the antenna end, I would to open
up the converter and solder in a ground wire on the coax sheild
terminal. This would kill off common mode currents.

This would give my antenna feeder system a matching transformer plus
give the antenna a direct path to ground.

Theoretically, I am I missing anything?

mike