Big Endian wrote:

How does one check the balance between two parallel feed wires into a
doublet antenna. Neon bulbs or some sort of meter gizmo?

tnx

d

YEP!!

An RF Ammeter will do just fine

Amos Keag wrote:

YEP!!

An RF Ammeter will do just fine

Balance requires that the currents in the two wires be equal in
magnitude and opposite in phase (or direction). How do you connect an RF
ammeter to determine this?

Roy Lewallen, W7EL

Wouldn't the clamp-on type ammeter as discussed previously provide that
information (provided a section of twin lead small enough to fit the
clamp were used?

Chuck

Roy Lewallen wrote:
Amos Keag wrote:


YEP!!

An RF Ammeter will do just fine


Balance requires that the currents in the two wires be equal in
magnitude and opposite in phase (or direction). How do you connect an RF
ammeter to determine this?

Roy Lewallen, W7EL

Sorry, when I read "RF ammeter", I thought only of the old type which
resembles a panel meter and has two terminals to connect in line with a
single conductor. A clamp-on type would indeed do the job, as we
discussed here not long ago.

Roy Lewallen, W7EL

chuck wrote:
Wouldn't the clamp-on type ammeter as discussed previously provide that
information (provided a section of twin lead small enough to fit the
clamp were used?

Chuck

Roy Lewallen wrote:
Amos Keag wrote:


YEP!!

An RF Ammeter will do just fine


Balance requires that the currents in the two wires be equal in
magnitude and opposite in phase (or direction). How do you connect an
RF ammeter to determine this?

Roy Lewallen, W7EL

"Roy Lewallen" wrote
Balance requires that the currents in the two wires be equal in
magnitude and opposite in phase (or direction). How do you connect
an RF
ammeter to determine this?
=====================================

It's unbelievably easy Roy, you just pass both wires together through
a clamp-on ammeter.
----
Reg.

Hi Roy,

I have a couple of RF current meters with freq. response from 10KHz to
100MHZ that are the types used for FCC part 15, DO-160E testing etc. and
have a transfer impedance of 0dB-ohm. They have an opening of about
1.6" dia. and I sqeeze the feedline together (spacing about 1.5")
temporarily and clamp over both conductors for measurement #1 and clamp
over just 1 of the conductors for measurement #2. I read the output of
the current probe with an RF power meter. In my case the current in a
single conductor was approximately 15dB above the differential current
which seemed to be pretty well balanced. Is there anything wrong with
this approach?

Larry Benko, W0QE


Roy Lewallen wrote:
Amos Keag wrote:


YEP!!

An RF Ammeter will do just fine


Balance requires that the currents in the two wires be equal in
magnitude and opposite in phase (or direction). How do you connect an RF
ammeter to determine this?

Roy Lewallen, W7EL

Amos Keag wrote:
An RF Ammeter will do just fine

What if the first current is one amp at zero degrees and the
other current is one amp at 45 degrees. Is that balanced?
--
73, Cecil http://www.qsl.net/w5dxp

Big Endian wrote:
How does one check the balance between two parallel feed wires into a
doublet antenna. Neon bulbs or some sort of meter gizmo?

The easiest way is to use a large sampling toroid such
that the balanced line can be fed through the toroid.
A ten-turn sampling coil will indicate any unbalance.
Note that the balanced line needs to be centered with
respect to the toroid and needs to be moved along the
feedline to obtain maximum accuracy. Ideally, the toroid
needs to be located at a standing wave current maximum
point. Since my choke-balun is always located at a current
maximum point, I can easily monitor my feedline balance.

You can also use smaller toroids on each line and then
superpose the two readings. But the two toroids need to
be identical which is no small requirement.
--
73, Cecil http://www.qsl.net/w5dxp

In article ,
Cecil Moore wrote:

Big Endian wrote:
How does one check the balance between two parallel feed wires into a
doublet antenna. Neon bulbs or some sort of meter gizmo?

The easiest way is to use a large sampling toroid such
that the balanced line can be fed through the toroid.
A ten-turn sampling coil will indicate any unbalance.
Note that the balanced line needs to be centered with
respect to the toroid and needs to be moved along the
feedline to obtain maximum accuracy. Ideally, the toroid
needs to be located at a standing wave current maximum
point. Since my choke-balun is always located at a current
maximum point, I can easily monitor my feedline balance.

You can also use smaller toroids on each line and then
superpose the two readings. But the two toroids need to
be identical which is no small requirement.

An unbalanced condition would have a meter indication, like current
flow? Balanced the meter needle would not move? I want to monitor this
condition on the feedline in the shack from the Johnson KW matchbox.

Big Endian wrote:
An unbalanced condition would have a meter indication, like current
flow? Balanced the meter needle would not move?

Yes, for a balanced condition, the meter needle should
not move.
--
73, Cecil http://www.qsl.net/w5dxp