Thank you.

I think it may be a common mode problem. There is no choke on the
dipole. I will bring it closer to resonance.

- Dan kb0qil

Richard Clark wrote:
On Sun, 25 Feb 2007 07:14:54 -0800, dansawyeror
wrote:
resonates at about 7.7 MHz.
On low power the tuner creates a very low SWR.
according to the SWR Watt meter the system
appears to transmit well over 200 watts.
When it is transmitting the SWR reads about 1.1 to 1.

Hi Dan,

The Meter is either not as good as you claim it to be (it doesn't
accurately perform at low power); OR
you have common mode problems (classic).

Do you choke the dipole?

73's
Richard Clark, KB7QHC

dansawyeror wrote:
I think it may be a common mode problem. There is no choke on the
dipole. I will bring it closer to resonance.

Dan, are you measuring that power on the input or
output of the tuner? If at the output of a transceiver
with autotuner, for instance, the forward power is
the sum of the transmitter power and reflected power.
--
73, Cecil http://www.w5dxp.com

Owen Duffy wrote:
The so called "forward power" and "reflected power" are notional values,
but not actual power "components". The only power is the average rate at
which energy passes a point, and it is in one direction or the other.

That statement depends upon the definition of "power"
being used. The IEEE Dictionary has a different
definition of power than does a physics textbook.
The net power is the average rate at which net energy
passes a point. The net power is the difference between
the forward joules/sec and the reflected joules/sec.

Instead of using the word "power", let's switch over to
the dimensions of power, i.e. "joules/second". Those
joules are indeed *actual energy components*.

The so called "forward power" is a forward traveling
EM wave containing energy moving at the speed of light.
There are indeed actual forward joules/sec moving past
a point on the transmission line.

The so called "reflected power" is a rearward traveling
EM wave containing energy moving at the speed of light.
There are indeed actual reflected joules/sec moving past
a point on the transmission line.

Note that an EM wave cannot stand still. According
to the theory of relativity, EM waves always move at
the speed of light (taking VF into account).

Standing waves consist of a forward traveling wave
containing joules/second and a reflected traveling
wave containing joules/second. The joules/second in
those two waves are supplied during the transient
power-on state. During steady-state, that energy has
not yet reached the load. But the total energy contained
in the transmission line during steady-state is exactly
the amount of energy needed to support the forward
traveling wave and the reflected traveling wave. Standing
waves would not be possible without those two real EM
wave energy components traveling in opposite directions.

At power-down, assuming the source is disconnected
from the transmission line, all of the forward wave
energy and reflected wave energy stored in the lossless
transmission line is eventually dissipated in the load.
That happens during a time when the source is supplying
zero energy.
--
73, Cecil http://www.w5dxp.com

On Mon, 26 Feb 2007 08:10:49 -0800, dansawyeror
wrote:

I think it may be a common mode problem. There is no choke on the
dipole. I will bring it closer to resonance.

Hi Dan,

One very simple test is to fire up your rig and note the SWR. Patch
in a short, loose length of transmission line to the existing run
(about an eighth wave) and fire up the rig again.

Did the SWR change?

If so, you are being SWR whipped by Common Mode currents.

You can keep introducing different lengths of line until you find 1:1
(unlikely, but perhaps close) and let it go at that. This will be a
single frequency solution, but take care that it does NOT cure Common
Modality. Instead, it adds a vertical component to your transmission
(maybe).

This is not always good as that same transmission line (plus
extension) may run past RF sensitive devices (like intercoms, VCRs,
light dimmers, etc.) that go whacko. It may also fill in the nulls of
your dipole (sometimes good, sometimes bad).

73's
Richard Clark, KB7QHC

On Mon, 26 Feb 2007 10:25:10 -0000, "Jeff" wrote:

I am sorry, but I disagree

Hi Jeff,

Your appologies aside, it is the convention you are disagreeing with.
The injection of such terminology as
'transmitted' power
is not part of conventional usage in this discussion. The trap here
of inventing terms is that your term would not account for Ohmic loss
as either forward or reverse power in the balance sheet (and this loss
could well be the source of mismatch); and yet this loss would have a
definite impact on what is "transmitted."

A simple instance proves this. Add a 14 Ohm resistor in series at the
feed to a perfect quarterwave radiator. The reverse reading would be
nada, the forward reading would NOT be "transmitted" power. Further,
the conventional usage of terms seen in this thread would still be
accurate.

73's
Richard Clark, KB7QHC

" Your appologies aside, it is the convention you are disagreeing with.

I think that most engineers would disagree, what you are describing is the
power delivered into the load, both forward and reverse power exist both by
convention and as a real entity.

The injection of such terminology as
'transmitted' power
is not part of conventional usage in this discussion.

Perhaps that is sloopy wording on my part, I sould have said 'power
transmitted to the load'; I was not implying radiated power.

73
Jeff

On Mon, 26 Feb 2007 18:10:42 -0000, "Jeff" wrote:

what you are describing is the
power delivered into the load,

Hi Jeff,

Perhaps you should re-read your original complaint.

Perhaps that is sloopy wording on my part

So it would seem. ;-)

73's
Richard Clark, KB7QHC

Jeff wrote:
Perhaps that is sloopy wording on my part, I sould have said 'power
transmitted to the load'; I was not implying radiated power.

Indeed, "transmitted power" could simply mean power
from the transmitter, i.e. "source power".
--
73, Cecil http://www.w5dxp.com

"Jeff" wrote in
.com:

The so called "forward power" and "reflected power" are notional
values, but not actual power "components". The only power is the
average rate at which energy passes a point, and it is in one
direction or the other.

I am sorry, but I disagree, forward power is real and can be measured,
or if you wish separated out with a circulator or isolator. What you
are describing could be called 'transmitted' power or power delivered
into a mismatched load, but that it different from forward power, or
the power delivered by the source.

Jeff,

You dropped a number of terms he
- 'transmitted' power;
- power delivered into a mismatched load;
- forward power;
- power delivered by the source;

The power delivered to a load (of any kind) from a lossless transmission
line section, is the same as the power delivered by the source. In the
case of the lossy line, then the line characteristics and load impedance
also need to be taken into account to calculate the power lost in the
line section, and it is not as simple as using up a dB/100' rating in a
table (unless the line is matched).

You assertion that you have travelling forward and reflected power waves
on the transmission line runs into a problem when you try to analyse the
combination of both at a point (eg the input to the line) as power
doesn't combine vectorially.

When you devise configurations with circulators, isolaters, directional
couplers, hybrids etc to "trap and reroute" reflected power, you have
probably changed the nature of the load on a line section and that
accounts for why the reflected power seems to have been isolated from
forward power.

Owen

"
The power delivered to a load (of any kind) from a lossless transmission
line section, is the same as the power delivered by the source.

So it is your contention that power is not reflected at a mismatch. The wave
certainly is so the power contained in the reflected portion must be as
well.

You assertion that you have travelling forward and reflected power waves
on the transmission line runs into a problem when you try to analyse the
combination of both at a point (eg the input to the line) as power
doesn't combine vectorially.

I was not trying to analyse the combination of any wave on the line ("power"
waves, whatever they may be, or anything else), I was merely noting that you
can quantify and measure the power contained the both the forward and
reflected waves and they are real quantities.

Jeff