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Author Topic: New Toy - Antenna Analyzer  (Read 5120 times)
N5INP
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« on: November 15, 2013, 04:54:42 PM »

Got a new toy today - A Comet CAA-500 Ant. Analyzer.

I cut wires for a test dipole for 52 MHz in the middle of the 6 meter band (9 feet - 4.5 feet/side) and connected it to a center insulator I made. The insulator is made of PVC pipe and has an SO-239 with some wires running internally to the ant. connection terminals. Ideally the dipole should have resonated at 52 MHz. The analyzer showed it resonated at 50.4 MHz.

468 / 50.4 = 9.29 feet.

.29' * 12 = 3.4"

The antenna looked 3.4 " longer than it should have been. The reason was the wires inside the insulator made the difference,  which makes sense. So I'll have to account for those lengths when making the final antenna.

I'm very impressed with this instrument now.  :-+

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W9FIB
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« Reply #1 on: November 15, 2013, 05:55:48 PM »

Best investment I ever made as well!
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N5INP
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« Reply #2 on: November 15, 2013, 06:49:09 PM »

Best investment I ever made as well!

Makes a decent signal generator too.  Smiley
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KQ6EA
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« Reply #3 on: November 16, 2013, 06:13:10 PM »

I also have one, and it was money well spent!

Jim
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N5INP
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« Reply #4 on: November 17, 2013, 04:27:13 PM »

I also have one, and it was money well spent!

Jim

It sure made my 6m dipole project easy. Got that sucker tuned right in the center of the band. Now if I can only find another soul to talk to on the band I'll be in hog heaven.  Wink
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WA8ZYT
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« Reply #5 on: November 18, 2013, 11:01:18 AM »

A 5 element beam will bring 6 meters alive for you.
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K9ZF
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« Reply #6 on: November 18, 2013, 12:31:11 PM »

How does it compare with the MFJ analyzers?  Cost?  Performance?

I've always wanted one, but hate to spring ~$300+ for an MFJ product....

73
Dan

--
K9ZF
Amateur Radio Emergency Service, Clark County Indiana. EM78el
former K9ZF /R no budget Rover ***QRP-l #1269
Check out the Rover Resource Page at:
<http://www.qsl.net/n9rla>
List Administrator for: InHam+grid-loc+ham-books
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--
K9ZF
Amateur Radio Emergency Service, Clark County Indiana. EM78el
The once and future K9ZF /R no budget Rover
 ***QRP-l #1269
Check out the Rover Resource Page at:
<http://www.qsl.net/n9rla>
List Administrator for: InHam+grid-loc+ham-books
Ask me how to join the Indiana Ham Maili
KQ6EA
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« Reply #7 on: November 18, 2013, 12:53:27 PM »

It would depend on which MFJ analyzer you compare it to. I had an MFJ 269, and while I was lucky that mine worked OK (we all know about MFJ "Quality Control"), I know other people who weren't so lucky with their MFJ analyzers.

It's a bit simpler, not reading out the reactance figures, but few people I know who have an MFJ analyzer actually use that information.

It's built MUCH better, has a very solid feeling, and the tuning is smoother, especially in the UHF range. The manual isn't as comprehensive as the MFJ manual, but then the instrument doesn't display as many parameters, or make as many different measurements, so a simpler manual is sufficient.

There were some complaints with the early models about the UHF connector not being the correct size, but I never had any problem with mine, which I bought about 18 months ago.

If I *need* the reactance figures for something, or a graph, I'll use my RigExpert AA-520, but for fast tuning of a portable antenna, these can't be beat.

Yes, it's expensive, but then gas is almost $4 a gallon these days, too.

Jim
« Last Edit: November 18, 2013, 12:58:21 PM by KQ6EA » Logged
N5INP
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« Reply #8 on: November 18, 2013, 03:39:46 PM »

It's built MUCH better, has a very solid feeling, and the tuning is smoother, especially in the UHF range.

I agree it's very solid and has that quality feel to it you can't fake. The only problem is the case is all painted metal and scratches very easily. I laid it on my ladder and got some small scratches on the back. I have since ordered the soft case for it for field work.

Quote
There were some complaints with the early models about the UHF connector not being the correct size, but I never had any problem with mine, which I bought about 18 months ago.

I read that in the reviews. The issue was with early models that used some metric version of the UHF female (who knew there was such a thing?), but they have long since corrected that problem.

Quote
If I *need* the reactance figures for something, or a graph, I'll use my RigExpert AA-520, but for fast tuning of a portable antenna, these can't be beat.

I was very pleased with how it worked as I tested my 6 meter dipole. I'm bringing it to a ham friend's house tomorrow because he wants to test his antennas. I told him he might find out something he doesn't want to know.  Cheesy
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KQ6EA
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« Reply #9 on: November 18, 2013, 07:23:04 PM »

I bought mine to use with my Buddipole/Buddistick, but it's also saved my bacon at work a few times.

With have a couple of 72MHz wireless headset-type intercoms we use for certain operations, and they just weren't working right, and had very poor range.
I used the Comet to determine that the antennas were resonant at 54 MHz (someone had purchased replacement whips and didn't know they had to be trimmed!), and the Comet helped me get them cut to the correct frequency in a matter of minutes.
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KA3YAN
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« Reply #10 on: November 20, 2013, 11:55:30 AM »

I was really stuck on what analyzer I wanted...or was willing to pay for.  I few years ago I purchased an MFJ-259B and it worked relatively well.  What I really didn't like was how quickly it would eat through a whole box of AA batteries (especially if something happened to bump the ON/OFF switch).  It was also a PITA to change batteries.  So I decided to sell some unused items and the 259B and upgrade to a nicer unit.  The question was whether I wanted the Comet CAA-500 or the RigExpert AA-600 (the AA-520 is out of production).  Obviously I needed to consider cost as an important variable, but I also considered user reviews, features, and applications.  In the end the features won me over with the RigExpert AA-600.

That's not to say there isn't a place for the CAA-500.  If I had a million dollars laying around, it would be on my list of things to buy.  I like the cross needles that instantly show a real-time value of SWR and Z.  What I really liked best about the AA-600 was the ability to graphically show the sweep over a range of frequencies and to be able to operate the analyzer using a computer.  While there are still limitations with the AA-600, it really is a fantastic piece of equipment for the price.

I don't condemn the MFJ analyzers, they're not bad...they're just built to MFJ's "high standards" which may or may not suite your needs in the long run. I guarantee that YMMV with anything from MFJ.

73,
Brad KA3YAN
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W5ZZT
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« Reply #11 on: November 20, 2013, 11:33:30 PM »

I may be old fashion but what do you really need an analyzer for? I just use my rig at low power to see where I am resonant.

I am just wondering what the benefit is.

Thanks
Harold
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N5INP
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Posts: 835




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« Reply #12 on: November 21, 2013, 05:17:13 AM »

I may be old fashion but what do you really need an analyzer for? I just use my rig at low power to see where I am resonant.

I am just wondering what the benefit is.

Convenience Harold. Unless you want to take your transmitter to the bench where you are working on an antenna, or to the field point where you want to adjust an antenna, yea you can get by with doing what you say. But with a handheld analyzer like the CAA-500, you can simply and quickly sweep the band and get a very good idea of how the antenna is working. And with the more expensive units like the rigrunners, you can get a graph of the resonant properties.

An analogy would be a builder that uses a pneumatic nail gun to build a house. Why use that, when a simple hammer will still do the job? Because it saves time and it's easier. But yea you can still build a house with a framing hammer (or test an antenna with a transmitter).  Smiley

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