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Author Topic: Antenna Analyzer help - RigExpert AA-230 Pro or AA-520 ?  (Read 7467 times)
KJ6PVR
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Posts: 25




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« on: September 05, 2011, 10:26:02 PM »

I'm looking into buying Antenna analyzer and after extensive research I decided to go with RigExpert toys. It's a lot of money, but it's a solid quality product as far as I can tell from the reviews. Besides, I only want to make this purchase once.
So, the only thing I can't decide on is WHICH ONE.  I narrowed my search down to AA-230 PRO and AA-520. They are about the same price , AA-520 includes UHF as well. AA-230PRO goes "only" up to 230 MHz, but it has a TDR (Time Domain Reflectometer)mode, ideal for locating cable faults.
I'm a new ham and I'd like to get an opinion from people that use analyzers. How much desirable is it to have 70cm band coverage on an analyzer? I do use 70 cm frequencies once in a while but I'm getting out there with my ground plane antenna I made for 2m just fine.
I'm starting to experiment with HF and building some antennas, but that will be covered just fine with both analyzers.
Any ideas and inputs to help me decide?
Thank you,
Tom, KJ6PVR
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KD8DEY
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Posts: 352




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« Reply #1 on: September 05, 2011, 11:04:17 PM »

2 questions

1- How many Hams do you know that look for "cable faults", chop out a bad section of coax, put on a new pair of PL-259's and a barrel connector VS Just buying a fresh run of coax?

2 - Do you plan on using UHF anytime in the future and want to be able to adjust it for the best match possible?
 Grin
73
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KJ6PVR
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« Reply #2 on: September 05, 2011, 11:16:21 PM »

1. That's exactly why I posted my question, I'm a new ham and don't know many yet, so I can't answer this question. But judging from your reply, I guess not too many.
2. Yes I do want to use UHF in the future.

Now, since you answered, thank you btw., I'll throw in another point. Looking at a comparison table of both analyzers, AA-520 will work only with 50 ohms reference impedance for SWR measurement, where AA-230 PRO will work with 25, 50, 75, 100 Ohm. Is it something I should be concerned about?
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KD8DEY
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« Reply #3 on: September 05, 2011, 11:27:41 PM »

Since modern rigs want to see a 50 ohm impedance ......

Unless you are building some sort of antenna and want to measure directly at the feed point with an impedance other than 50 ohms and doesn't include some sort of matching network (kinda doubtful since you would be so close to the antenna that maybe your body would interact with the antenna)........  Grin

Also,

Not many people would be willing to stand at the top of a ladder to connect their analyzer directly into a full wave loop ............
« Last Edit: September 05, 2011, 11:42:53 PM by KD8DEY » Logged
KJ6PVR
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Posts: 25




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« Reply #4 on: September 05, 2011, 11:37:14 PM »

Since modern rigs want to see a 50 ohm impedance ..............  Grin

I know I know... :-)
What's the advantage of the other settings for different impedance in AA-230 PRO ?
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KD8DEY
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Posts: 352




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« Reply #5 on: September 05, 2011, 11:49:09 PM »

Bells and whistles

Which would you rather have
a Volks wagon or Ferrari ?

at one time Didn't they both use a version of the same 4cyl engine?

PS

I just looked online and saw that they were both way north of 600 bux ouch.

For HAM use a lot of us find that the ole MFJ 259/269 will pretty much do what we need for 1/2 the cost (Even cheaper if you buy one used from somebody that only needed to use it a couple times then decided to sell)

I have the 259 myself with the optional accessories.
(Which reminds me I need to remove the batteries for storage till I get around to needing it again).
if you are willing to do a little math there are a few tricks you can do with it like calculating the actual velocity factor of your coax (Helpful when making coax baluns etc)

http://www.mfjenterprises.com/pdffiles/MFJ-259B.pdf

http://www.mfjenterprises.com/pdffiles/MFJ-269.pdf
« Last Edit: September 06, 2011, 12:07:44 AM by KD8DEY » Logged
KJ6PVR
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Posts: 25




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« Reply #6 on: September 05, 2011, 11:56:42 PM »

Bells and whistles

Which would you rather have
a Volks wagon or Ferrari ?

at one time Didn't they both use a version of the same 4cyl engine?

Sorry, I drive Subaru :-)
Well, looks like AA-520 might be the winner here for me. Thanks for the input.
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KD8DEY
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« Reply #7 on: September 06, 2011, 12:12:03 AM »

PS
Enjoy and welcome to the hobby
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AD5X
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« Reply #8 on: September 06, 2011, 04:56:39 AM »

I have the AA-230 (not the PRO).  Excellant instrument.  Unless you really need the TDR functionality, the '230PRO isn't worth the extra $100.  Unlike the AA-530, the AA-230 and AA-230PRO also show the sign of any reactance measured (so you can easily determine whether it is inductive or capacitive).  Of course, you can figure this out but I prefer the instant read-out.  And the '230 and '230PRO also have UHF connectors (with the AA-530 you'll need UHF/N adapters for most of your measurements).  Frankly, most of your work will be below 440MHz.  I mean - how often will you be tweeking on a 440MHz antenna?

Just my humble opinion.

Phil - AD5X
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KJ6PVR
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« Reply #9 on: September 06, 2011, 08:10:26 AM »

Frankly, most of your work will be below 440MHz.  I mean - how often will you be tweeking on a 440MHz antenna?

Just my humble opinion.

Phil - AD5X

This was exactly the whole point of this thread, to hear from people about the usage of the analyzers. I had a feeling 440MHz may not need that much attention as other bands, especially HF. But what do I know, no experience to back it up. $100 is not that big of a difference, but there are other features on AA-230 PRO that people find useful and AA-520 doesn't have.
As far as MFJ, after reading many many reviews and opinions, I'd rather stay away and spend more money on real quality gadget that will last a looong time.
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K8AXW
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« Reply #10 on: September 06, 2011, 08:30:41 AM »

Man, if you have the green to blow, go for it!  I bought the first model MFJ came out with... no counter and had to by an external counter to go with it.  That was a bummer but... with anything new, that's the way it sometimes goes.

My point is, with this 'stone axe' analyzer I can tune my antennas fast, find problems fast and I was able to spend money I didn't have on something else. 

Just MHO.  Welcome to the hobby.  You sound like someone who intends to have fun!
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KJ6PVR
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Posts: 25




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« Reply #11 on: September 06, 2011, 08:49:39 AM »

Man, if you have the green to blow, go for it!  I bought the first model MFJ came out with... no counter and had to by an external counter to go with it.  That was a bummer but... with anything new, that's the way it sometimes goes.

My point is, with this 'stone axe' analyzer I can tune my antennas fast, find problems fast and I was able to spend money I didn't have on something else. 

Just MHO.  Welcome to the hobby.  You sound like someone who intends to have fun!

I'm not even going into debate that MFJ seems to be a cheap (but expensive) chinese "thing" that could have cost a lot less if it wasn't for MFJ having manufacturer deal only with them. Seems like it's 50-50 chance you get a good product that you don't have to re-solder yourself. Again , this is not based on my own experience, just reading a lot from actual users. This is not MFJ bashing post , but I'd rather support Ukrainians that make superb product in this case.
 
We're talking about $300 price difference here. It's really nothing for the essential tool anyone who is dealing with antennas and building their own AND if one intends to stay in the hobby. People spend $300 on any junk over few months not even noticing it.

You're right, I intend to have fun, that's why I'm careful where I spend my money, thanks for your input as well, much appreciated.
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KF5IIL
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Posts: 22




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« Reply #12 on: September 06, 2011, 12:49:06 PM »

In our club, amongst our membership, we have several different brands of analyzers represented.  I personally have and use an MFJ-259b, and it works great, but the RigExpert is a very nice tool also and has some neat features not really found on other devices in its price range.  I think that by and large, either of those brands work pretty well (I see a lot of them being used out there with great success... and they are still selling, so something must be working).

The more important thing is that regardless of what analyzer you get, you will be doing yourself the best favor by just getting a decent one.  And the RigExperts are generally quite decent.  The antenna is the real difference maker and that tool will give you more insight as to how well it is working than anything else, as far as a practical field solution goes.

Personally, I wouldn't worry so much about UHF features unless you have some specific and recurring needs in that frequency range.  The HF region is where the most practical effect of using the analyzer occurs for most amateur operators. 

As a bit of background, I do a lot of portable operations on weekends and that means I am setting up antennas over different grounds all of the time.  So the analyzer is perfect for getting my field antennas optimized for whatever my operating session's requirements will be.  But it has simplified all of my efforts at home when I have added to or changed my antenna configurations here. 

73,
David
KF5IIL
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N3OX
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« Reply #13 on: September 06, 2011, 06:14:56 PM »

Of course, you can figure this out but I prefer the instant read-out. 

Hmm, knowing the sign of the reactance could be useful.  Sometimes you have to figure it out in comparison with a model or something.  For most situations it's straightforward to figure it out... for many antennas if it's capacitive, reactance will decrease with frequency.  If it's inductive, reactance will increase with frequency.  This works most of the time because most antennas are decently described by a resistance in series with a reactance.

But here's a good counterexample, measured this weekend, of a situation where this method of inferring the sign of reactance is simply wrong:

http://n3ox.net/files/impedance.jpg

This is the impedance of a short antenna matched to 50 ohms with a shunt coil in parallel at the base of the antenna.  Below the 50 ohm resonant frequency of the matched system, it shows an inductive reactance that decreases rapidly with frequency, then a capacitive reactance that does the expected thing, but then flips and starts decreasing with frequency.  When I took the data with my MFJ-259B (without looking at the model data first, so I didn't expect this), I basically had the reactance data flipped upside down and it was particularly weird above 7070kHz or so where the reactance started going back down with no zero crossing.

In this particular case where there is an EXPLICIT parallel circuit and/or the antenna is easy to model, the confusion can be easily rectified by comparison with the model (what I did...), or you can remove the shunt coil and measure the impedance directly (which I did, and that did the expected thing, capacitive and decreasing as frequency moves up toward resonance and inductive and increasing as frequency moves past and above resonance).

If you're trying to do pure experiments with no model guidance on a complicated antenna actually knowing the sign of reactance could be really useful, and "figuring it out" would be possible but much more involved.  Some antennas may have  fundamentally more complicated impedance behavior than a series LCR circuit around the operating frequency, and then just being able to read out the sign of reactance might prevent some confusion (provided it actually resolves the phase at a given frequency and doesn't infer it from the way it changes with frequency or something!

Quote
Frankly, most of your work will be below 440MHz.  I mean - how often will you be tweeking on a 440MHz antenna?

I agree that tweaking on 70cm is not very important.  It's nice to be able to check the SWR, but the last beam I built for 70cm I didn't tweak at all... just built it based on a model (which was slightly tweaked from published dimensions at W4RNL's site) and put it up.  I measured the SWR with an old Radio Shack VHF/UHF SWR meter and it was lowest right where the model said. This was a 50 ohm direct feed design.

I use my analyzer to measure inductors and capacitors and stubs as much or more than I use it to measure finished antennas, but a lot of that utility would not work well at UHF.
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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
KF7DS
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Posts: 181




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« Reply #14 on: September 11, 2011, 07:41:57 AM »

Bells and whistles

Which would you rather have
a Volks wagon or Ferrari ?

at one time Didn't they both use a version of the same 4cyl engine?

Sorry, I drive Subaru :-)
Well, looks like AA-520 might be the winner here for me. Thanks for the input.

Get the RgExpert analyzer that fits your needs. I have the mfj 259b and the 230 and the 259b is more difficult to use and mediocre build quality.

The 230 is very simple to use and built very well. It is worth every extra $ more than the mfj 259b and then some.

Don
KF7QZB
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