MFJ-269 Antenna Analyzer experience
 

Hi all

I'm looking at purchasing an MFJ269 antenna analyser and keen to hear
experience of others in this group regarding this or similar analysers.
Appears to be ideal if it is as good as MFJ claim.


--
Peter VK6YSF

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

MFJ-269 Antenna Analyzer experience
 

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Peter wrote:
Hi all

I'm looking at purchasing an MFJ269 antenna analyser and keen to hear
experience of others in this group regarding this or similar analysers.
Appears to be ideal if it is as good as MFJ claim.


A good place to check for reviews is at eham.net.

http://www.eham.net/reviews/
http://www.eham.net/reviews/detail/803


- --
Best Regards, Keith
http://home.comcast.net/~kilowattradio/
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MFJ-269 Antenna Analyzer experience
 

Peter wrote:
Hi all

I'm looking at purchasing an MFJ269 antenna analyser and keen to hear
experience of others in this group regarding this or similar analysers.
Appears to be ideal if it is as good as MFJ claim.

I have one and find it extremely handy for a variety of tasks such as
measuring the length or velocity factor of coax lines or the impedance
of ferrite cores. But ironically, the one thing it's almost completely
useless for, at my QTH, is analyzing antennas. Induced fields from TV,
FM, and AM broadcast stations are so high that the MFJ isn't able to
detect its own signal. This isn't unique to the MFJ -- I've had the same
problem with a very expensive HP digital impedance meter, and revert to
my old GR bridge with a tuned receiver for a detector when I want to
actually measure an antenna's impedance. For me the MFJ is worthwhile
just for the other functions it provides, but it might or might not be
for you. Just keep in mind that, depending on your QTH, it might not be
able to actually measure antenna impedances.


Roy Lewallen, W7EL

MFJ-269 Antenna Analyzer experience
 

"Roy Lewallen" wrote in message
...
Peter wrote:
Hi all

I'm looking at purchasing an MFJ269 antenna analyser and keen to hear
experience of others in this group regarding this or similar analysers.
Appears to be ideal if it is as good as MFJ claim.

I have one and find it extremely handy for a variety of tasks such as
measuring the length or velocity factor of coax lines or the impedance of
ferrite cores. But ironically, the one thing it's almost completely
useless for, at my QTH, is analyzing antennas. Induced fields from TV, FM,
and AM broadcast stations are so high that the MFJ isn't able to detect
its own signal. This isn't unique to the MFJ -- I've had the same problem
with a very expensive HP digital impedance meter, and revert to my old GR
bridge with a tuned receiver for a detector when I want to actually
measure an antenna's impedance. For me the MFJ is worthwhile just for the
other functions it provides, but it might or might not be for you. Just
keep in mind that, depending on your QTH, it might not be able to actually
measure antenna impedances.


Roy Lewallen, W7EL

Roy

All comments noted. I do in fact live within 2km of an AM transmitter
although I believe it's not that high powered and I also have an FM
transmitter within 5km, therefore I'm interested in the details of your
location in relation to the various transmitters.

Regards
--
Peter VK6YSF

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

MFJ-269 Antenna Analyzer experience
 

"Keith" wrote in message
...
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Hash: SHA1

Peter wrote:
Hi all

I'm looking at purchasing an MFJ269 antenna analyser and keen to hear
experience of others in this group regarding this or similar analysers.
Appears to be ideal if it is as good as MFJ claim.


A good place to check for reviews is at eham.net.

http://www.eham.net/reviews/
http://www.eham.net/reviews/detail/803


- --
Best Regards, Keith
http://home.comcast.net/~kilowattradio/
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Thanks for the links Keith

Regards

--
Peter VK6YSF

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

MFJ-269 Antenna Analyzer experience
 

On Sat, 15 Aug 2009 22:47:05 -0700, Roy Lewallen
wrote:

Peter wrote:
Hi all

I'm looking at purchasing an MFJ269 antenna analyser and keen to hear
experience of others in this group regarding this or similar analysers.
Appears to be ideal if it is as good as MFJ claim.

I have one and find it extremely handy for a variety of tasks such as
measuring the length or velocity factor of coax lines or the impedance
of ferrite cores. But ironically, the one thing it's almost completely
useless for, at my QTH, is analyzing antennas. Induced fields from TV,
FM, and AM broadcast stations are so high that the MFJ isn't able to
detect its own signal. This isn't unique to the MFJ -- I've had the same
problem with a very expensive HP digital impedance meter, and revert to
my old GR bridge with a tuned receiver for a detector when I want to
actually measure an antenna's impedance. For me the MFJ is worthwhile
just for the other functions it provides, but it might or might not be
for you. Just keep in mind that, depending on your QTH, it might not be
able to actually measure antenna impedances.


Roy Lewallen, W7EL
I live in a very rural area and mine works as advertised.

I don't use it very much because it gives quick and complete answers.

MFJ-269 Antenna Analyzer experience
 

"Peter" wrote in
. au:

Hi all

I'm looking at purchasing an MFJ269 antenna analyser and keen to hear
experience of others in this group regarding this or similar analysers.
Appears to be ideal if it is as good as MFJ claim.



Peter,

Effective exploitation of the capability of this type of analyser depends
on a sound understanding of transmission lines, and of the instrument's
own limitation. The availability of these analysers at low cost, and the
perception that they are a magic bullet has lead to a lot of pseudo
technical nonsense being proposed. The magic is more in the user's
capability than the box, and buying the box doesn't buy knowledge and
understanding... but the device can help develop knowledge and
understanding.

I have not used a '269 (though I have extensively used a '259B), but I
suspect that it does not display the sign of X. Estimation of the sign of
X in the '259 and similar instruments is an issue, and confuses many
users. There are propositions that sign of X is easily determined from
the slope of X with frequency at a point... but whilst that is true for
an ideal passive component, it is not true in general.

These instruments are often used in pursuit of the questionable goal of
resonance, and the instrument used to show resonance by observing X=0, or
X approximately zero, or a local minimum for X at some frequency on the
assumption that X changes sign at that point and that resonance of
something is indicated.

I wrote some notes entitled "In pursuit of dipole resonance with an
MFJ259B" at http://vk1od.net/blog/?p=680 that canvasses the behaviour of
the instrument in such an application, and flags the issues in
measurement. You may find them interesting.

Others have raised the issue that these instruments use a broadband
detector, which works fine so long as the internal oscillator has low
harmonic content and dominates the detector. If you let one of these
things time out, the oscillator is shut down, and if you see indication
on the meters, then energy from another source is of sufficient magnitude
to be concerned about the accuracy of measurements.

Owen

MFJ-269 Antenna Analyzer experience
 

Peter wrote:

Roy

All comments noted. I do in fact live within 2km of an AM transmitter
although I believe it's not that high powered and I also have an FM
transmitter within 5km, therefore I'm interested in the details of your
location in relation to the various transmitters.

Regards

Roughly 10 - 15 miles from here is a ridge about 800 feet higher than my
location. On top are virtually all the TV and FM, and a number of the
AM, transmitters for the Portland Oregon metropolitan area. A single
strong transmitter is likely to be enough to confuse an antenna
analyzer, though. Filtering is possible, of course, but you have to take
care to design filters to have minimal effect on measured impedances
while still filtering effectively. This can sometimes be challenging
depending on the strength of the interfering signal and how far it is
from the measurement frequency.

I also have to be careful when working on audio circuitry -- on several
occasions I've tracked down "hum" as demodulated TV video, and I end up
having to include VHF decoupling and shielding to audio circuits. Don't
know much about the nature of HDTV signals, but it might not be so bad
if it doesn't have as much energy in the AF range when demodulated. It's
bound to drive untuned antenna analyzers bonkers, though.

Roy Lewallen, W7EL

MFJ-269 Antenna Analyzer experience
 

"Peter" wrote in message
. au...
Hi all

I'm looking at purchasing an MFJ269 antenna analyser and keen to hear
experience of others in this group regarding this or similar analysers.
Appears to be ideal if it is as good as MFJ claim.


Hi Peter,

I can highly recommend the Rigexpert AA-200A:
http://www.rigexpert.com/index?s=aa200

Unlike the MFJ unit, this is a full vector analyzer. You can also save plots
and then transfer them to your computer for archiving. The lates firmware
allows measurements at both 50 Ohms and 75 Ohms and I believe one can now
also move the reference plane to the end of the coax. Batteries last
forever, it's about 1/4th the weight, can display data in both graphical and
tabular format.
I've owned the MFJ, Autek, AEA and Timewave- the AA-200A blows them all
away. Oh yeah, the signal source is synthesized and can make a very nice
signal generator that is rock stable.

Dale W4OP

MFJ-269 Antenna Analyzer experience
 

Dale Parfitt wrote:
"Peter" wrote in message
. au...
Hi all

I'm looking at purchasing an MFJ269 antenna analyser and keen to hear
experience of others in this group regarding this or similar analysers.
Appears to be ideal if it is as good as MFJ claim.


Hi Peter,

I can highly recommend the Rigexpert AA-200A:
http://www.rigexpert.com/index?s=aa200

Unlike the MFJ unit, this is a full vector analyzer. You can also save plots
and then transfer them to your computer for archiving. The lates firmware
allows measurements at both 50 Ohms and 75 Ohms and I believe one can now
also move the reference plane to the end of the coax. Batteries last
forever, it's about 1/4th the weight, can display data in both graphical and
tabular format.
I've owned the MFJ, Autek, AEA and Timewave- the AA-200A blows them all
away. Oh yeah, the signal source is synthesized and can make a very nice
signal generator that is rock stable.

Dale W4OP




Except that it looks like the RigExpert has an untuned detector, just
like the others. The schematic SUBVHF6.pdf shows a couple of RF
switches and a AD8307 log detector. The PLL synthesizers are up at 1+
GHz, so maybe there's a filter and mixer somewhere else. I couldn't
find a block diagram.