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| Reviews Summary for AMQRP AA-908/Micro-908 Antenna Analyst |
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Reviews: 5
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Average rating: 4.0/5
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MSRP: $230
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Description: A microcomputer-controlled DDS-based antenna analyzer with a range of <1 MHz to 60 MHz. It is also a platform for the AMQRP Micro-908 daughterboard and will support the (optional) KK7P DSP board, providing DSP-based audio filtering as well as numerous other functions. Fully software configurable with available source code to allow the user to download and/or write new features and/or fix problems.
It has been offered primarily as a kit (check website for availability) but it should be possible to find someone that will assemble it if you do not wish to tackle the installation of SMD components.
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More info: http://www.amqrp.org/kits/micro908/index.html
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write your own review of the AMQRP AA-908/Micro-908 Antenna Analyst.
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KC7FYS
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Rating: 2/5
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Oct 14, 2009 19:51
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Wont be surprised to see one at a garage sale soon.
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Time owned: more than 12 months
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I hesitate to tender a negative review for several reasons. Chief among them is my respect for the man behind this project and his stature in the homebrew community. I am also not a super technical ham, but have successfully built several kits--the AA908, however, was purchased built from a rather smart ham who unloaded it on me when the project had shown some signs of being dead. That was about 2007. Now on the reflector, you will periodically hear the intrepid voice of yet another bitter AA908 owner ask, Is this project dead? Folks are respectful, but generally consider it a project that started out with a big puff of steam, but now smells like a dead fish. The USB port will likely never happen, nor will the PSK31 functionality. Its kind of quaint to watch the video documentation that came with this rather large unit--which seems to get larger every time I sit it next to my Autek analyzer on the same shelf. It works, but it is not a work in progress at all. I regret having bought it sometimes, and other times consider it the way the hobby is. Buy it, but dont expect it ever to change at this point. Visit the AMQRP website to see the rather cute ^Roadmap^ of what was to be. One might just as easily photoshop on a Vegematic: it slices, dices, and makes julienne fries in seconds.
Actually, the vegematic is cheaper and maybe more fun.
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WB2SRF
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Rating: 4/5
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Jun 15, 2006 13:16
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Great learning experience
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Time owned: more than 12 months
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I agree with the other reviewer's comments. To keep things in perspective, this is a great project if you wish to have hands on experience and learn about how things work. The source code is available and is good to study the framework to see how the microcontroller is being used to perform the computations and measurements. This project is evolving and seems to have many future applications.
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KC7ULI
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Rating: 5/5
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Jan 3, 2006 11:17
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more than the sum of the parts
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Time owned: 3 to 6 months
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Well, this is a kitted project and it is a well done kit. Rough edges, yes, but consider that this is produced by the AMQRP group who are doing this through their love of the hobby. As stated, the kit is well done with pretty good documentation. It's a complex electronic device that is well designed for its price class, with good quality parts and a lot of existing features and lots and lots of potential. And the rough edges are getting smoother all the time.
A work in progress to be sure, but that is part of the allure of this. If you want an MFJ269, get one, but if you don't like MFJ or if you want to have some pretty good fun, then this tool is what you might want to consider. The Palstar ZM30 antenna analyzer is a commercialized version of this design, and the software is essentially the same. The layout in that design is different for their mechanical implementation, but that device gets great reviews (12 of 12 are 5's so far). The Palstar doesn't have provisions for the DSP, as far as I recall, and it probably isn't ever going to be anything more than an antenna analyzer like the AA908 (well, it probably can work as a stable programmable VFO just like the AA908, since the DDS system used is one of the neat features of this design).
The Palstar isn't a kit, so when you buy it (for not a lot more than the kit version of the AA908 plus DSP, etc.) it works out of the box. But the AA908 is a growing, evolving project that should continue to add features and capabilities. It will provide a lot of satisfaction in the building process, it will hone your construction skills, it will work as an excellent and flexible test and measurement tool for your shack (much more than just an antenna analyzer).
Finally, the user community is growing, the support network is superb (and very helpful) and about the only issue I see is with the continued availability of the kits. I suspect that George and crew at AMQRP don't want to make a career out of kitting this project, so I wouldn't be surprised if they aren't working to move this over to another small company that will continue to produce the product into perpetuity. Watch the kit user reflector for unbuilt kits if AMQRP is out. They do come up once in a while and they are well worth building up.
Larry
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AA2YS
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Rating: 4/5
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Jan 3, 2006 07:09
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Nice and flexible, but some rough edges
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Time owned: more than 12 months
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The first review covers all of the technical aspects very well, so I won't repeat them.
I don't think it quite emphasized enough, though, that the AA-908 really is a "work in progress". It's not unusual to have several firmware releases over the course of a few days to fix problems that come up.
The intention for the AA-908 was always advertised to be a "general computing platform" that could be used for an antenna analyzer, audio filter, portab le PSK interface, rig control, etc. The antenna analyzer and audio filter apps are there, but the others have been coming "real soon now" for well over a year, and don't even get mentioned any longer, so I presume that they've stagnated.
Don't get me wrong - this is a fine device, and fun to build, but don't go into it with the expectation that you're going to be getting something that "just works" out of the box.
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KA7OEI
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Rating: 5/5
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Dec 29, 2005 17:34
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If it won't do what you want it to do, change it!
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Time owned: 3 to 6 months
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This unit is primarily offered as a kit. Be forewarned that it has a lot of surface-mount parts, so if you aren't prepared to do some fine detail work, you might want to consider other options - like finding someone (a friend or a "kitbuilders" group) that can help! I personally enjoy kits and "getting my hands dirty" in building/improving them - but this may not be everyone's "cup of tea."
Originally designed for use up to 30 MHz, a newly-available DDS synthesizer board (and a firmware upgrade) expands its range up to 60 MHz. This unit will display the frequency, the resistance, and the reactance - and it can determine the sign of the reactance. It tunes in 10 Hz steps and its frequency accuracy/stability is that of the crystal reference oscillator onboard.
It also has a serial port to allow updating of the firmware when new features/bugfixes come out as well as providing remote control by a computer allowing one to graphically plot the SWR/Z/X of an antenna: It is really quite neat to be able to sweep your antenna system across all of HF to see if it *really* resonates where it is supposed to!
Also available is the KK7P DSPx board (see the TAPR site for more info) that allows one to provide a suite of audio DSP filtering capabilities such as noise reduction, bandpass filtering, automatic notching, etc. The software for this filter, too, is upgradable via the serial port.
Future capabilities include the possibility of a standalone PSK31 terminal without a PC (using a computer keyboard that can plug into a jack) and using the '908's LCD readout on TX/RX. Of course, you could theoretically program whatever DSP/DDS project you think of.
In addition to measuring antenna properties, it will also measure the value of a capacitor or inductor and can function as a signal generator/VFO with an output in the 0 to 5 dBm area (more or less...)
Caveats: As mentioned, it comes as a kit, so you'll want to keep that in mind if you want to get one. Also, it is a "work in progress" so the firmware is constantly evolving (but getting better!) If you are able to do 'HC908 assembly language (the source code for this is available freely) you'll be able to contribute to the effort! While there are a few bugs and quirks in the system, it does, for the most part, work very well! Note that it isn't an ultra-precision instrument and its best accuracy occurs when reading nearest to 50 ohms, but it is certainly good enough to tell you what's going on with your antenna system.
As a side comment: The main thing that limits the low end frequency response of this unit are the coupling capacitors in the reflectometer bridge and DDS board. As they are, they are usable down to about 500 KHz (maybe a bit lower) but theoretically, it should be able to go down to a few 10's of KHz with some capacitor changes - something that could be of interest to a LowFER. (The DDS synthesizer itself is capabile of generating frequencies down to 10 Hz with this software.)
Note that this kit is not always available: The "kitting" will only occur if/when there is deemed sufficient demand (and available time by those doing it!) so you'd have to check the web site - but it may be possible to find one (assembled or not) that someone else is selling. When I got my AA-908/Micro908 kit (with DSP board, which added around $70 or so) it was approx. $300 - but the price is certainly likely to vary over time and with availability.
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