"Peter" wrote in message
...

"Owen Duffy" wrote in message
...
"Peter" wrote in
. au:

...
I must admit I had assumed that the 269 analyzer display the sign of
the reactance, I will have to reread the ad.

Ah, you were looking for honesty in advertising!

The online guff on the MFJ259B says:
"Read Complex Impedance as series resistance and reactance (R+jX) or as
magnitude (Z) and phase (degrees)."

The MFJ259B definitely does *not* show phase angle or reactance as
negative for cases where X is actually negative.

The same words appear in the MFJ269 online page, so it may also be a
misrepresentation.

I see in the MFJ269 manual, the same pretence over the sign of phase and
reactance. It contains the words "Besides Z, an angle between zero and 90
degrees is shown. This angle represents the phase difference between
current and voltage at the terminals of the analyzer."

Of course, a phase angle between "zero and 90 degrees" does not represent
"phase difference between current and voltage at the terminals of the
analyzer" in the case of a capacitive impedance.

Honesty in advertising... think again.

Owen

What was I thinking! I was impressed with what was being claimed.

I will continue with my product research and you can expect me to float
some other manufactures device on this group soon for comments.

Peter VK6YSF

Again- look at the RigExpert A-200A. Batteries seem to last forever, it's
USB upgradable and it DOES resolve the sign of R +/-JX.

Dale W4OP

"Dale Parfitt" wrote in message
...

"Peter" wrote in message
...

"Owen Duffy" wrote in message
...
"Peter" wrote in
. au:

...
I must admit I had assumed that the 269 analyzer display the sign of
the reactance, I will have to reread the ad.

Ah, you were looking for honesty in advertising!

The online guff on the MFJ259B says:
"Read Complex Impedance as series resistance and reactance (R+jX) or as
magnitude (Z) and phase (degrees)."

The MFJ259B definitely does *not* show phase angle or reactance as
negative for cases where X is actually negative.

The same words appear in the MFJ269 online page, so it may also be a
misrepresentation.

I see in the MFJ269 manual, the same pretence over the sign of phase and
reactance. It contains the words "Besides Z, an angle between zero and
90
degrees is shown. This angle represents the phase difference between
current and voltage at the terminals of the analyzer."

Of course, a phase angle between "zero and 90 degrees" does not
represent
"phase difference between current and voltage at the terminals of the
analyzer" in the case of a capacitive impedance.

Honesty in advertising... think again.

Owen

What was I thinking! I was impressed with what was being claimed.

I will continue with my product research and you can expect me to float
some other manufactures device on this group soon for comments.

Peter VK6YSF

Again- look at the RigExpert A-200A. Batteries seem to last forever, it's
USB upgradable and it DOES resolve the sign of R +/-JX.

Dale W4OP
Thanks Dale

I have just had a look at the RigExpert site. Look impressive, but the
MFJ269 at about $400US was about my limit.
I think I will take a step back and conduct a more scientific review of all
of the antenna analyzers on offer, there for you should get sick of my
postings over the next couple of weeks/months.
I must say that the ability to save and analyze data on the lap top is an
appealing feature.

Regards

Peter VK6YSF

http://members.optushome.com.au/vk6ysf/vk6ysf/main.htm

Peter wrote:

I have just had a look at the RigExpert site. Look impressive, but the
MFJ269 at about $400US was about my limit.
I think I will take a step back and conduct a more scientific review of all
of the antenna analyzers on offer, there for you should get sick of my
postings over the next couple of weeks/months.
I must say that the ability to save and analyze data on the lap top is an
appealing feature.

Regards

Peter VK6YSF

http://members.optushome.com.au/vk6ysf/vk6ysf/main.htm

Have a look at the AIM 4170 at http://www.arraysolutions.com/

I have that and a MFJ analyzer.

For a quick antenna adjustment, the MFJ is easier to use.

For in depth analysis, the AIM can't be beat.

If I had only one, I would prefer to have the AIM.


--
Jim Pennino

Remove .spam.sux to reply.

From:
Date: Wed, 19 Aug 2009 Time: 15:45:00

Have a look at the AIM 4170 at http://www.arraysolutions.com/

I have that and a MFJ analyzer.

For a quick antenna adjustment, the MFJ is easier to use.

For in depth analysis, the AIM can't be beat.

If I had only one, I would prefer to have the AIM.


I'll second that. The AIM4170 *is* expensive, especially when you add on
15% UK sales tax (and it took me 18 months to take the plunge), but it
does so much more than the MFJ units.

Instant computer readout, in nice graphical form, of all the antenna
system parameters over any selected frequency range up to 170MHz. They
claim to have interference reduction capability to minimize the effects
of close AM MW signals, but I don't live close enough to an AM
transmitter to test this.

The other nice thing about the 4170 is the ability to control it
remotely. With the 4170 connected to the antenna system in the shack and
controlled by a local PC, it's then possible to remotely access the PC
from a cheapy notebook in the backyard. You can make antenna adjustments
out in the yard and see the effects of the changes immediately, without
having to repeatedly walk back indoors to look at the 4170 PC. This
feature alone has saved me a *lot* of time:

http://homepage.ntlworld.com/wadei/A...Control%20HOWT
O%20-%20090106.pdf

Well worth a look.

--
73
Ian, G3NRW

Ian Wade G3NRW wrote:

The other nice thing about the 4170 is the ability to control it
remotely. With the 4170 connected to the antenna system in the shack and
controlled by a local PC, it's then possible to remotely access the PC
from a cheapy notebook in the backyard. You can make antenna adjustments
out in the yard and see the effects of the changes immediately, without
having to repeatedly walk back indoors to look at the 4170 PC. This
feature alone has saved me a *lot* of time:


I tend to make my SWR readings right at the antenna, whenever possible.
That length of coax to the xceiver will only make it look better in most
cases.

- 73 de Mike N3LI -

Michael Coslo wrote:
Ian Wade G3NRW wrote:

The other nice thing about the 4170 is the ability to control it
remotely. With the 4170 connected to the antenna system in the shack and
controlled by a local PC, it's then possible to remotely access the PC
from a cheapy notebook in the backyard. You can make antenna adjustments
out in the yard and see the effects of the changes immediately, without
having to repeatedly walk back indoors to look at the 4170 PC. This
feature alone has saved me a *lot* of time:


I tend to make my SWR readings right at the antenna, whenever possible.
That length of coax to the xceiver will only make it look better in most
cases.

- 73 de Mike N3LI -

One of the advantages of the 4170 is the ability to calibrate out the
effects of the feedline.


--
Jim Pennino

Remove .spam.sux to reply.

From: Michael Coslo
Date: Fri, 21 Aug 2009 Time: 09:51:05

I tend to make my SWR readings right at the antenna, whenever possible.
That length of coax to the xceiver will only make it look better in
most cases.

- 73 de Mike N3LI -

Mike,

With the 4170 I can calibrate the instrument to compensate for the
feeder impedance. After calibration, the indicated impedance at the TX
end of the feeder is actually the antenna feedpoint impedance. This
makes life a *lot* easier.

--
73
Ian, G3NRW

Ian Wade G3NRW wrote:
From: Michael Coslo
Date: Fri, 21 Aug 2009 Time: 09:51:05

I tend to make my SWR readings right at the antenna, whenever
possible. That length of coax to the xceiver will only make it look
better in most cases.

- 73 de Mike N3LI -

Mike,

With the 4170 I can calibrate the instrument to compensate for the
feeder impedance. After calibration, the indicated impedance at the TX
end of the feeder is actually the antenna feedpoint impedance. This
makes life a *lot* easier.

Oaky, well good enough. My vertical uses a stub on the feedline, so I
have to be out there anyhow.with a connector in the line. Seems like 6
of one, half dozen of the other situation.

- 73 De Mike N3LI -

Ian Wade G3NRW wrote:

Mike,

With the 4170 I can calibrate the instrument to compensate for the
feeder impedance. After calibration, the indicated impedance at the TX
end of the feeder is actually the antenna feedpoint impedance. This
makes life a *lot* easier.

Easy, yes. But If you're not careful, this can be a great example of
garbage in, garbage out.

I frequently calculate out the feedline transformation when making
antenna measurements. But it's essential that you realize a small error
in estimating the feedline loss(*) or length can sometimes result in a
very large error in calculated impedance. This is particularly true if
there's a large impedance mismatch between the line and antenna.
Transmission line impedance, which can vary a lot from the specified
nominal value (I've seen +/-20% with coax, more with ladder line), also
has an effect on the result. So whenever I need accurate results or
whenever the line Z0 is quite different from the antenna impedance, I
start by carefully measuring the properties of the actual transmission
line I'll be using.

If you're not convinced, spend a few minutes playing with something like
N6BV's TLW calculator that comes with the ARRL Antenna Book.

(*) Some simplified techniques ignore transmission line loss altogether.
This can lead to very inaccurate results in some situations. And loss is
often quite different than the specified value, so it really has to be
measured if it makes a significant difference.

Roy Lewallen, W7EL

"Peter" wrote in
. au:


"Dale Parfitt" wrote in message
...

"Peter" wrote in message
...

"Owen Duffy" wrote in message
...
"Peter" wrote in
. au:

...
I must admit I had assumed that the 269 analyzer display the sign
of the reactance, I will have to reread the ad.

Ah, you were looking for honesty in advertising!

The online guff on the MFJ259B says:
"Read Complex Impedance as series resistance and reactance (R+jX)
or as magnitude (Z) and phase (degrees)."

The MFJ259B definitely does *not* show phase angle or reactance as
negative for cases where X is actually negative.

The same words appear in the MFJ269 online page, so it may also be
a misrepresentation.

I see in the MFJ269 manual, the same pretence over the sign of
phase and reactance. It contains the words "Besides Z, an angle
between zero and 90
degrees is shown. This angle represents the phase difference
between current and voltage at the terminals of the analyzer."

Of course, a phase angle between "zero and 90 degrees" does not
represent
"phase difference between current and voltage at the terminals of
the analyzer" in the case of a capacitive impedance.

Honesty in advertising... think again.

Owen

What was I thinking! I was impressed with what was being claimed.

I will continue with my product research and you can expect me to
float some other manufactures device on this group soon for
comments.

Peter VK6YSF

Again- look at the RigExpert A-200A. Batteries seem to last forever,
it's USB upgradable and it DOES resolve the sign of R +/-JX.

Dale W4OP
Thanks Dale

I have just had a look at the RigExpert site. Look impressive, but the
MFJ269 at about $400US was about my limit.
I think I will take a step back and conduct a more scientific review
of all of the antenna analyzers on offer, there for you should get
sick of my postings over the next couple of weeks/months.
I must say that the ability to save and analyze data on the lap top is
an appealing feature.

Peter,

It helps to identify what you really need from the instrument. The
difficulty in doing that is foreseeing where an unstructured learning
journey might take you.

You will tend to arrive a points where you want to measure something just
beyond your existing capability. If the quest is for pure learning, then
just concentrate on the things that are within scope, and enjoy the
learning.

I admit that it is a bit of an old world view of ham radio, that it is
quintessentially a technical learning activity... but call me a dinasour.

The resolution of sign with the '259B is not a show stopper, but it is a
convenience issue and in the hands of a person with inadequate knowledge,
it is potentially misleading.

TLLC (http://www.vk1od.net/calc/tl/tllc.php) can refer impedance made at
one point on a known transmission line (eg the tx end) to another point
(eg the load end). Of course, uncertainty of the TL parameters
contributes to measurement uncertainty. This technique is ok for one off
measurements, but would be very labour intensive for a sweep with
hundreds of observations.

The ability to calibrate the feedline 'fixture' as part of a VNA
measurement system provides the convenience of measurement referred to
your preferred reference plan. The AIM4170 is (as I understand it) half
of a VNA, but that should be enough to do the same thing.

So, for the advantages of the ham grade VNA over the MFJ259B, you pay
more money, get better measurement resolution (the AD converters have
better resolution than the MFJ259B), have capability for automation of
measurement referred to a convenient reference plane, but... you lose
portability... though there is no reason why a ham grade VNA with a basic
display system couldn't be portable.

Owen