> One day an "old-timer" touched a small neon? bulb to one balanced line
> output post of my MFJ948 tuner and then touched to the other output post.
> There was a difference in brightness. Is this a useful method to test for
> balance.
It is not a valid test.
Radiation comes from charge acceleration, which is related to
current and distance (ampere-feet). There also are induction effects
caused by voltage (charge distribution) and current (charge
movement).
Balance actually requires equal and exactly opposite-phase
currents, as well as equal and exactly opposite voltages on the
feeder, but current balance is by far the most important concern.
Even a simple current meter won't tell anything, unless you can
clamp it over both conductors. In the case where you clamp a
current meter over both conductors at the same time, you look for
zero current because it is reading common mode current. That at
least means radiation is minimal at that area of the feedline.
Is there another test (short of RF ammeters)? My antenna
> connected was a long-wire 500' vee sloping from 90' at apex to about 30'
> at the end of one wire and 20' for the other wire.. Midway each wire
> passed over trees which were of different heights. What method can one
> use to bring the antenna and feed line into balance--with a standard(?)
> tuner?
You can't without changes at the antenna.
In order to balance the feedline, you'd have to balance the feedline
at the antenna end...as well as at the house end. While it can be
done, it may not be worth the work. I ran into an even worse
problem playing with ZL3REX's 160 antenna. We could not get the
balanced line balanced, because it ran under his inverted L...and
the Inverted L was an unbalanced antenna. Even a balun at the L
didn't help much.
What we did was just balance the line in the house, by clamping a
clamp-on current meter over both leads at the same time. We
wound up with a 2:1 voltage unbalance at the tuner, but minimum
noise pickup from the house wiring.
If you can't make it perfect, then just go for zero common mode
current. Forget the light bulbs, or current readings in each wire.
73, Tom W8JI
W8JI@contesting.com
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