mfj-998 autotuner opinions

Discussion in 'Amateur Radio Equipment Reviews' started by N0NDV, Aug 1, 2008.

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  1. AB8YL

    AB8YL Ham Member QRZ Page

    Updated review of MFJ-998

    As promised, here is an update to my previous review comments about the MFJ-998 Legal Limit Intellituner:

    After having to return the original unit and two "replacement" units to MFJ due to an assortment of equipment defects, I received a fourth tuner. Actually, Bob (998 specialist at MFJ) expedited shipment of the replacement unit even before I returned the third defective unit. As with the other replacements, he included a prepaid UPS shipping label for me to use when shipping the defective tuner. Bob's responsive support is the highlight of an otherwise rather unpleasant ordeal.

    I've been using the latest replacement tuner for more than five weeks, now, and have to say that I'm very pleased with its performance. When I received it I performed the obligatory visual check with the cabinet's cover removed. I noted that the 31 relays were from a different manufacturer than those equipped in the previous three tuners. Also, the analog meter was of a different style. I don't know whether these components represent "improvements", signify an earlier vintage of the product or are simply there because MFJ obtains parts from multiple suppliers. Whatever the case may be, the unit is tuning my 80m droopy dipole to no worse than 1.2:1 across the entire band. I've been getting good signal reports from Florida to California with about 1 KW PEP; so it appears my signal is being transferred to the antenna fairly efficiently.

    Complaints: Well... No major problems have emerged, so I have to nit-pick a bit this time. The analog Forward Power meter needs to be calibrated. In the quiescent no-signal-present state it indicates about 7 Watts. Secondly, the analog meter (different type from that equipped in the previous three tuners) is illuminated by a rather harsh white light, in contrast to the softer amber glow used to illuminate the other meter type. Since I often operate with the room illuminated only by my computer display and the meters on the rig, tuner and amplifier, the bright light is a bit annoying. However, it's something I can deal with myself, either by adding some resistance to the meter's lamp circuit or, perhaps, by affixing an amber film to the bezel.

    Overall, I'm happy that my persistence seems to have finally paid off. I'm still a bit concerned that the tuner may be failure prone; but that's something that only time will reveal. Making the unit more user-serviceable by including a schematic diagram would certainly be a plus. For now my plan is to reverse-engineer the main board in order to create my own schematic; but that may prove to be a rather time-consuming task, especially since many of the components are densely positioned surface mount devices and my eyesight is significantly poorer than 20/20. Once some owner has created an accurate drawing, the intellectual property that MFJ is protecting will be "out of the bag". MFJ could save us the trouble and score some "customer-friendly" points by simply offering the schematic to 998 owners.

    73 de AB8YL - Bob
    Pataskala, OH
     
    Last edited: Oct 11, 2008
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