MFJ-993B Intellituner Automatic Antenna Matching Device
MFJ-993B Intellituner. The review below was originally posted in a slightly different form on eHam.net. Since writing it, I have added the MFJ-998 high-power auto-tuner. Most of the comments below also apply to the 998, but I will attempt to post a review of that tuner at a later time.
I bought this "tuner" (a matching device is not really a "tuner," even though that is the common name for such a device) for the express purpose of tuning a skywire loop on 160 and 75. The antenna is fed with 450-ohm window line so I needed a balanced antenna capability, but I also wanted the versatility of having a memory tuner for other bands and antennas. I was wary of relying on a balun inside the tuner on the feedline input side, but I also wanted a matching unit that I could use for quick, automatic tuning on other bands with the loop and other antennas I anticipate experimenting with...balanced feedline and coax. There's nothing else on the market anywhere in the price range that does it all as the 993B does. Other automatic tuners suggest outboard baluns and a length of coax to the tuner. It is also true that one does not read the reviews on eHam without seeing the comments about an alleged lack of quality control at MFJ.
I'm pleased to report the 993B handles the loop beautifully. It's a bit touchy on the low end of 160 and on 10 meters but I suspect I could play with the feedline and fix that. I'm hesitant to do that because it works so well everywhere else...across all 9 HF ham bands! Besides, the way I had to run the feedline into the shack alongside coax cables may have more to do with that than the tuner does. (Click here to see more on the construction of my skywire loop antenna and the feedline method I use.)
I see no evidence of the internal balun getting hot from excessive loss and I get amazing signal reports with my 100 watts. I have no RF-in-the-shack problems. My TS-2000 seems happy. And everything on the tuner seems to be well made and solid. Yes, I peeked inside and it looks professionally constructed. I know signal reports are anecdotal and not really scientific proof of anything...other than the guy on the other end of the QSO heard me well enough to give me a signal report. But I have been very pleased with how this piece of gear has worked. I can only compare the antenna system that includes the "tuner" to my other antennas on which I don't use any kind of external matching device, and the loop with the 993B almost always win the competition.
I bought the rather pricey interface cable for my Kenwood TS-2000 and it works perfectly. (Note that you do not need a 12V power source if you use this cable. The tuner gets its power from the rig.) Once I've tuned up on a frequency, I only hit the "AT" button on the rig the next time I'm there and, with one click, I'm at 1.5:1 or better. It's fun to touch that button and hear a dead-sounding band suddenly come to life! No L and C controls to crank on or a spreadsheet taped to the wall so I can crank the controls enough to get the match somewhere in the ballpark. The memory seems relatively broad so I don't have to re-tune unless I go a considerable distance in either direction. There are thousands of auto-tune memory positions available so I doubt I'll run out. I'm anal retentive so I keep the AM power level set at 10 watts so I can quickly click over, hit the PTT on the mic, and confirm that the SWR is where it is supposed to be, not only on the tuner cross-needle meter and digital readout but on the rig's SWR meter as well. By the way, I have no standard of comparison but the watt meter built into the 993B seems to be reasonably accurate.
I have not tried the manual tuning capability, nor do I use the audio beep feature. The frequency counter readout seems close to correct. The only points I would knock off so far are for the rather confusing manual and the really complicated menu system. Otherwise, this tuner is well worth the price and is a good, versatile antenna tuning "system" that has a place in most any ham shack with more than an antenna or two.
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