Roy, W7EL wrote:
"So using the same analysis, you`d have to conclude that vertically
polarized waves can`t propagate by ground waves either."

Earth isn`t perfectly conductive but even so permits propagation of
vertically polarized waves.

Another expert, Kraus says on page 412 of his 1950 edition of
"Antennas":
"The electric field of a wave traveling along a perfectly conducting
surface is perpendicular to the surface....However, if the surface is an
imperfect conductor, such as the earth`s surface or ground, the
electric-field lines have a forward tilt near the surface.... Hence, the
field at the surface has a vertical component Ey and a horizontal
component Ex. The component Ex is associated with that part of the wave
that enters the surface and is dissipated in heat. The Ey component
continues to travel along the surface.

Best regards, Richard Harrison, KB5WZI

That's a much better explanation of the phenomenon of ground wave
analysis than the first one you put forth.

Roy Lewallen

Richard Harrison wrote:
Roy, W7EL wrote:
"So using the same analysis, you`d have to conclude that vertically
polarized waves can`t propagate by ground waves either."

Earth isn`t perfectly conductive but even so permits propagation of
vertically polarized waves.

Another expert, Kraus says on page 412 of his 1950 edition of
"Antennas":
"The electric field of a wave traveling along a perfectly conducting
surface is perpendicular to the surface....However, if the surface is an
imperfect conductor, such as the earth`s surface or ground, the
electric-field lines have a forward tilt near the surface.... Hence, the
field at the surface has a vertical component Ey and a horizontal
component Ex. The component Ex is associated with that part of the wave
that enters the surface and is dissipated in heat. The Ey component
continues to travel along the surface.

Best regards, Richard Harrison, KB5WZI

Roy, W7EL wrote:
"That`s a much better explanation of the phenomenon of ground wave
analysis than the first one you put forth."

True! Kraus was a much better explainer than I will ever be, I fear.

Best regards, Richard Harrison, KB5WZI

On Mon, 30 Aug 2004 01:04:57 -0400, "Tim Perry"
wrote:


"Walter Maxwell" wrote in message
.. .

snip

I was just about to tell you what I use, but Richard, above, beat me to
it. For
HF measurements this bridge, the General Radio 1606-A, is the Cadillac of
all
bridges. It 's been the bridge of choice for nearly every AM broadcast
engineer
in determining t he impedance of AM broadcast antennas since it came on
the
market in 1955.

i have yet to see one at a US broadcast station. the meter that is usually
found, and used is the delta OIB-1 or OIB-3
http://www.deltaelectronics.com/data/oib1&3.htm

Hi Tim,

I can't disagree with you here, because my knowledge is from several years back.
I'm not familiar the Delta except by reputation--all I've heard is that it's a
good instrument. The demise of General Radio is probably one reason the GR
instrument is no longer the instrument of choice, so the dividing line between
use of the GR and the Delta probably defines the end of one era and the
beginning of another.

Walt, W2DU

"Ian White, G3SEK" wrote in message
...
J. McLaughlin wrote:
Most interesting. Thanks.

You're welcome. Just one small point, though:

I have not used the AEA-CIA for R-X measurements. I always assumed
that firmware was used to guess at the sign of X, and it is not too
surprising (though disappointing) that the chap who wrote the software
might blank out small values of X altogether.

In case anyone's not following this closely, I had been writing about
the AEA-CIA blanking out values of X less than about 30 ohms. That is
not "small" by any standard, and it only happened on one side of zero.
It could not possibly have been a deliberate feature of the programming.

In contrast, the MFJ-269 (and probably the 259B) does deliberately blank
out small values - truly small values, that is - as X passes through
zero. This occurs exactly as explained in the manual, and is exactly as
it should be.
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

Ian, and others,

I have the 269 HF VHF UHF analyzer and noticed something strange. In
the "non-50 ohm" Advanced menu 3 mode, with the Zo set to 75 ohms, an
otherwise good 75 ohm load (please assume I know how to tell and I used a
low frequency to reduce errors) shows something like a 1.3 : 1 SWR. When I
called to ask about it, the first tech at MFJ seemed confused and clearly
did not understand. Another call, on another day resulted in a better tech,
but the response was to send it in for re-calibration. This also seems to
be a calculation rather than an adjustment, no?

Once you know Z it is a simple calculation to get to SWR for another Zo. Or
have I been smoking a bad brand...?

Woha! I see they have on line calibration manual for the 259B & 269 on
line!
http://www.mfjenterprises.com/MFJ-259Bcalibration.php
http://www.mfjenterprises.com/man/pd...alibration.pdf

I don't see anything other than "watch the blinking SWR" .(sounds like a
British insult) for the Advance 3 "calibration".

--
Steve N, K,9;d, c. i My email has no u's.

My MFJ 269 shows the SWR of a Tektronix 75 ohm termination as 1.0:1 up
to 77 MHz when Z0 is set to 75 ohms.

Roy Lewallen, W7EL

Steve Nosko wrote:

Ian, and others,

I have the 269 HF VHF UHF analyzer and noticed something strange. In
the "non-50 ohm" Advanced menu 3 mode, with the Zo set to 75 ohms, an
otherwise good 75 ohm load (please assume I know how to tell and I used a
low frequency to reduce errors) shows something like a 1.3 : 1 SWR. When I
called to ask about it, the first tech at MFJ seemed confused and clearly
did not understand. Another call, on another day resulted in a better tech,
but the response was to send it in for re-calibration. This also seems to
be a calculation rather than an adjustment, no?

Once you know Z it is a simple calculation to get to SWR for another Zo. Or
have I been smoking a bad brand...?

Woha! I see they have on line calibration manual for the 259B & 269 on
line!
http://www.mfjenterprises.com/MFJ-259Bcalibration.php
http://www.mfjenterprises.com/man/pd...alibration.pdf

I don't see anything other than "watch the blinking SWR" .(sounds like a
British insult) for the Advance 3 "calibration".

"Walter Maxwell" wrote in message
...
On Mon, 30 Aug 2004 01:04:57 -0400, "Tim Perry"

wrote:


"Walter Maxwell" wrote in message
.. .

snip

I was just about to tell you what I use, but Richard, above, beat me to
it. For
HF measurements this bridge, the General Radio 1606-A, is the Cadillac
of
all
bridges. It 's been the bridge of choice for nearly every AM broadcast
engineer
in determining t he impedance of AM broadcast antennas since it came on
the
market in 1955.

i have yet to see one at a US broadcast station. the meter that is
usually
found, and used is the delta OIB-1 or OIB-3
http://www.deltaelectronics.com/data/oib1&3.htm

Hi Tim,

I can't disagree with you here, because my knowledge is from several years
back.
I'm not familiar the Delta except by reputation--all I've heard is that
it's a
good instrument. The demise of General Radio is probably one reason the GR
instrument is no longer the instrument of choice, so the dividing line
between
use of the GR and the Delta probably defines the end of one era and the
beginning of another.

Walt, W2DU

in part, the OIB (Operating Impedance Bridge) is popular because the normal
transmitter is the (usual) frequency source and interruptions to
transmissions can be brief or non-existent.
in typical use the bridge is inserted using a hot jack or J plug.
the engineer must be careful at all time to avoid touching exposed RF as the
resulting burns are painful and long lasting.
the meter itself has some effect on the circuit tuning: sometimes a
permanent version is installed at the common point of a phased array.
sometimes special jacks are employed that add a bit of inductance when the
meter is removed.

Steve Nosko wrote:

I have the 269 HF VHF UHF analyzer and noticed something strange.
In the "non-50 ohm" Advanced menu 3 mode, with the Zo set to 75 ohms,
an otherwise good 75 ohm load (please assume I know how to tell and I
used a low frequency to reduce errors) shows something like a 1.3 : 1
SWR.

And it had correctly showed SWR=1.5 when Zo was set to 50 ohms?

When I called to ask about it, the first tech at MFJ seemed confused
and clearly did not understand. Another call, on another day resulted
in a better tech, but the response was to send it in for
re-calibration. This also seems to be a calculation rather than an
adjustment, no?

Once you know Z it is a simple calculation to get to SWR for another
Zo. Or have I been smoking a bad brand...?

I didn't check this feature as part of the review, but it should be
simply the inverse ratio of whatever resistances you choose to define as
your Zo values.

Woha! I see they have on line calibration manual for the 259B & 269
on line!
http://www.mfjenterprises.com/MFJ-259Bcalibration.php
http://www.mfjenterprises.com/man/pd...alibration.pdf

I don't see anything other than "watch the blinking SWR" .(sounds like
a British insult) for the Advance 3 "calibration".

The MFJ-269 had to go back after the review (which itself was a few
years ago) so unfortunately I'm no longer able to check your findings,
Steve.

But don't recalibrate it yet, because that would be stirring-in
additional variables which will muddy the waters right now. After the
present question has been resolved, you may be able to give the
calibration procedure a little more TLC than there was time for on the
production-line - but you'll need some precision standards to do it.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

On Tue, 31 Aug 2004 02:37:31 -0400, "Tim Perry"
wrote:

snip

Hi Tim,

I can't disagree with you here, because my knowledge is from several years
back.
I'm not familiar the Delta except by reputation--all I've heard is that
it's a
good instrument. The demise of General Radio is probably one reason the GR
instrument is no longer the instrument of choice, so the dividing line
between
use of the GR and the Delta probably defines the end of one era and the
beginning of another.

Walt, W2DU

in part, the OIB (Operating Impedance Bridge) is popular because the normal
transmitter is the (usual) frequency source and interruptions to
transmissions can be brief or non-existent.
in typical use the bridge is inserted using a hot jack or J plug.
the engineer must be careful at all time to avoid touching exposed RF as the
resulting burns are painful and long lasting.
the meter itself has some effect on the circuit tuning: sometimes a
permanent version is installed at the common point of a phased array.
sometimes special jacks are employed that add a bit of inductance when the
meter is removed.

Thanks, Tim, for the update on the OIB. It did refresh my memory concerning the
meter being used while the transmitter is on the air. That I now recall.

Walt, W2DU

"Ian White, G3SEK" wrote in message
...
Steve Nosko wrote:

I have the 269 HF VHF UHF analyzer and noticed something strange.
In the "non-50 ohm" Advanced menu 3 mode, with the Zo set to 75 ohms,
an otherwise good 75 ohm load (please assume I know how to tell and I
used a low frequency to reduce errors) shows something like a 1.3 : 1
SWR.

And it had correctly showed SWR=1.5 when Zo was set to 50 ohms?

Yep! An extensive sheck of known good loads showed that the MFJ was
working as expected with reasonable accuracy. I don't have numbers, but 50
ohm loads looked ok and SWR, Z etc all appeared to be reasonable. Just this
one problem. (I have access to Agilent "N" cal kits)



When I called to ask about it, the first tech at MFJ seemed confused
and clearly did not understand. Another call, on another day resulted
in a better tech, but the response was to send it in for
re-calibration. This also seems to be a calculation rather than an
adjustment, no?

Once you know Z it is a simple calculation to get to SWR for another
Zo. Or have I been smoking a bad brand...?

I didn't check this feature as part of the review, but it should be
simply the inverse ratio of whatever resistances you choose to define as
your Zo values.

Woha! I see they have on line calibration manual for the 259B & 269
on line!
http://www.mfjenterprises.com/MFJ-259Bcalibration.php
http://www.mfjenterprises.com/man/pd...alibration.pdf

I don't see anything other than "watch the blinking SWR" .(sounds like
a British insult) for the Advance 3 "calibration".

The MFJ-269 had to go back after the review (which itself was a few
years ago) so unfortunately I'm no longer able to check your findings,
Steve.

But don't recalibrate it yet, because that would be stirring-in
additional variables which will muddy the waters right now. After the
present question has been resolved, you may be able to give the
calibration procedure a little more TLC than there was time for on the
production-line - but you'll need some precision standards to do it.
--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

The problem is the I found nothing wrong when measuring in all the other
modes. Only this one problem and I believe this is a calculation in the
microprocessor, not anything that can be "calibrated" to correct. I was
asking if this is correct. I also see nothing in the MFJ cal procedure for
the 269 for this mode other than "watch the blinkin' SWR symbol" (I
indicates you have set a Zo other than 50.
--
Steve N, K,9;d, c. i My email has no u's.