I've been thinking about springing for an MFJ (or other) antenna
analyzer
to check on the myriad antenna's I've got around the place.
I noticed that most of the analyzers on the market (like the MFJ-269,
for ~$350.00)
only go down to 1.8 MHz. I do a lot of work with xtal radio's
(DX'ing), and have a lot of different AM (MW) antenna's strewn about
the property. I was wondering why they cut that portion out of their
instrument? No demand? Too exotic?
Does anyone know if the analyzer could be modified (add some
inductance, etc. somewhere) to bring it down to about 500kc? Thanks!
Chris, AI4MI

instrument? No demand? Too exotic?
Does anyone know if the analyzer could be modified (add some
inductance, etc. somewhere) to bring it down to about 500kc? Thanks!

Another thing to think about: most of the analyzers around are pretty
much useless on low freqs anyway due to interference from AM broadcast
signals.

I recently finished shunt feeding my tower for 160m, and found that
my AEA CIA analyzer was completely useless trying to measure the feed
impedance. In the end I just used a regular swr meter to adjust the
shunt feed. I don't remember exactly how low the AEA goes, but it is
below 1.8 MHz.

Tor
N4OGW/5

On 7 Feb 2006 11:40:57 -0800, "chris" wrote:

I've been thinking about springing for an MFJ (or other) antenna
analyzer
to check on the myriad antenna's I've got around the place.
I noticed that most of the analyzers on the market (like the MFJ-269,
for ~$350.00)
only go down to 1.8 MHz. I do a lot of work with xtal radio's
(DX'ing), and have a lot of different AM (MW) antenna's strewn about
the property. I was wondering why they cut that portion out of their
instrument? No demand? Too exotic?
Does anyone know if the analyzer could be modified (add some
inductance, etc. somewhere) to bring it down to about 500kc? Thanks!
Chris, AI4MI

If you are not adverse to building (I don't know why a ham would be)
look at the N2PK network analyzer. www.n2pk.com

wrote:
Another thing to think about: most of the analyzers around are pretty
much useless on low freqs anyway due to interference from AM broadcast
signals.

I recently finished shunt feeding my tower for 160m, and found that
my AEA CIA analyzer was completely useless trying to measure the feed
impedance. In the end I just used a regular swr meter to adjust the
shunt feed. I don't remember exactly how low the AEA goes, but it is
below 1.8 MHz.

Tor
N4OGW/5

Yes, it's ironic that the one thing "antenna analyzers" are pretty
useless for, in an urban environment at least, is analyzing antennas.

Some time back I mentioned how a "half wave filter" could be used to
reduce out-of-band signals without disturbing the measurement too much.
The postings should be possible to locate at groups.google.com. Please
read all postings, because I recall incorrectly saying that the filter
could be used at frequencies lower (for a lowpass) or higher (for a
highpass) frequency than the design frequency. I later corrected that. A
given filter is good over only about one HF band without significant
disturbance of the measurement.

Roy Lewallen, W7EL

chris wrote:

I've been thinking about springing for an MFJ (or other) antenna
analyzer
to check on the myriad antenna's I've got around the place.
I noticed that most of the analyzers on the market (like the MFJ-269,
for ~$350.00)
only go down to 1.8 MHz. I do a lot of work with xtal radio's
(DX'ing), and have a lot of different AM (MW) antenna's strewn about
the property. I was wondering why they cut that portion out of their
instrument? No demand? Too exotic?
Does anyone know if the analyzer could be modified (add some
inductance, etc. somewhere) to bring it down to about 500kc? Thanks!
Chris, AI4MI



Don't panic!

There is an Italian analyzer, 0-60MHz for about 150€ ( 180 US $ ) which is
based on the AD9851 from analog devices.

You need a computer so it's not a handheld.

It's a "half VNA", giving +/- 90 degrees phase info but that is normally not
a problem as it's easy to find out the sign anyway.

A new version is coming soon and covers 0.1 Hz to 160 MHz. I think I saw a
price of 240€ on that one.

The TenTec TAPR VNA, 0-100 MHz is a "real" VNA with full quadrature 360
degree phase info.

However, you do still need a computer.



Cheers

Dan / M0DFI

In article . com, "chris" wrote:
I've been thinking about springing for an MFJ (or other) antenna
analyzer
to check on the myriad antenna's I've got around the place.
I noticed that most of the analyzers on the market (like the MFJ-269,
for ~$350.00)
only go down to 1.8 MHz. I do a lot of work with xtal radio's
(DX'ing), and have a lot of different AM (MW) antenna's strewn about
the property. I was wondering why they cut that portion out of their
instrument? No demand? Too exotic?
Does anyone know if the analyzer could be modified (add some
inductance, etc. somewhere) to bring it down to about 500kc? Thanks!
Chris, AI4MI


take a look at:
http://www.timewave.com/TZ-900.html

Randy, K0CBH
Timewave

Chris,

The problem with low cost analyzers is that they use broadband detector
diodes. Strong local AM radio stations will cause an output from these
diodes and generate erroneus results. In fact, MFJ suggests a highpass
filter before the instrument in order to alleviate this problem (in
areas with strong local AM stations). MFJ discusses this issue in the
MFJ-259B manual which is a free download @
http://www.mfjenterprises.com/manuals.php.

However, a German ham has modified his unit for operation from 40 kHz
to 1.8 mHz. This is not a trivial mod and it is described on page 88
of his manual @
http://www.darc.de/distrikte/f/27/MF...andbuch1v4.pdf

Unfortunately it is all in German so you will have to use Google to
translate the appropriate sections. BTW - this is the most
comprehensive user manual for this analyzer available anywhere.
Includes testing, calibration, schematic diagram, numerous mods,
operating tips and techniques, and how to build accessories.

Hope this helps - Roger