Difference between Palstar AT2K and AT2KD?

Discussion in 'General Technical Questions and Answers' started by W7MP, Nov 14, 2019.

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  1. W7MP

    W7MP Ham Member QRZ Page

    I'm narrowing down options for a tuner for an AL-80B linear and have decided on the Palstar AT2K, however HRO and other outlets have two models of it and the descriptors don't tell me a lot about the differences. I drove down to HRO and even the folks in store didn't seem to know a ton about the differences or why there were two models from Palstar.

    As both are the identical price, I would tend to defer to the AT2K but would love to know under what use cases I might consider the AT2KD. Anyone have an idea?



    Thank you very much in advance,

    Adam W7MP
  2. K7TRF

    K7TRF Premium Subscriber QRZ Page

    The differential capacitor design (AT2KD) uses a butterfly style capacitor so that you're basically adjusting both the Input and Output capacitors at the same time. The upside is fewer controls to tune when finding a match so potentially quicker tuning. The downside is a slightly reduced impedance matching range.

    Here's a link to ARRL's review of the AT2K and AT2KD: http://www.arrl.org/files/file/ProductReviewsForDeb/2013/pr072013.pdf

    They're both very good tuners and for most applications either will work but if the antenna system you're trying to match presents difficult impedances on some bands (e.g. low resistance, high capacitive reactance load) the AT2KD might have a bit more trouble finding a good match.

    If you're not 100% set on the Palstar tuners I'd highly recommend an Ameritron ATR-30. Nothing against the Palstar line, but the ATR-30 is a really good tuner that will match just about anything and according to ARRL testing has very low loss and a wider tuning range than price comparable tuners. I've got one paired up with my AL-80B and it's a very nice combo.

    Here's a link to the ARRL tuner comparisons that shows the extra matching range and relatively low loss of the ATR-30: http://www.aricampobasso.it/downdocs.php?c=2011-12-06_20-09-41_DRPAAPP9 (hint, take a look at the matching tables for each tuner tested and notice both the losses at the extreme matching impedances and the places where tuners list a 'No Match' condition)
    Last edited: Nov 14, 2019
  3. K7MH

    K7MH Ham Member QRZ Page

    Yup. The Ameritron ATR30 is what I decided on.
  4. KD2ACO

    KD2ACO Platinum Subscriber Platinum Subscriber Life Member QRZ Page

    I've had the AT2KD for several years and thoroughly enjoy it. It's a nicely built unit.

    If I had to drive wild antennas (lots of experimenting), I might pick a unit with separate caps.

    As it is, I can use my fan dipole on bands it's not cut for with no problems with the "D" version.

    I had an MFJ with 3 tuning controls and the "D" is quicker to tune after a change of frequency on the fly.
    Last edited: Nov 15, 2019
    W7MP likes this.
  5. W6MK

    W6MK Ham Member QRZ Page

    I have used both an ATR30 and an AT2KD with doublets 100 to 200 ft. long fed with parallel
    conductor feedline on bands from 160M or 80M through 20M.

    An ATR30 or the AT2K will match a wider range of impedances/reactances/bands than than an AT2KD.
    For some of my antenna setups I could only match my antennas on my bands of choice with the ATR30.

    The AT2KD (and I assume the AT2K) is quick and easy to tune. Very smooth, resettable controls and setting
    markings/indexes. The ATR30, despite some corrective mechanical work on my part, is not nearly as
    smooth and easy to use as the Palstar tuners.

    Much will depend on the design and intended use of your antenna(s). If you are not going to work to
    control the parameters of your antenna to at least some degree, you will be better off with a wider range

    I purchased my ATR30 used. It was in excellent shape but needed some mechanical adjustment to tune
    as smoothly and easily as it could. The ATR30 has a built-in high power 1:1 current balun for using
    parallel feedline which makes it even more useful, potentially, than the Palstar tuners without external
    baluns. On the other hand a tuner that is very easy to use can be a real blessing.

    Long term, if you like antennas that require tuners, I think it makes good sense to buy the
    best, widest range, easiest-to-use tuner you can afford. That would include the higher-end
    Palstar tuners as well as the AT2K and AT2KD.
    W7MP likes this.
  6. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    The Palstar and the Ameritron ATR-30 are both very good.

    I bought my ATR-30 "new," and it tunes smoothly as silk, never a problem with that. I only use it on 80m/160m and not other bands, but on those bands it does a rather spectacular job.

    All the "loss" in tuners is in the inductor, so the bigger and fatter and heavier gauge the inductor is, the less loss it will have.

    My motto has always been, "the less transmitter power you run, the bigger your tuner needs to be" -- which is a truism, when it comes to loss and actually producing a signal.
    WA9UAA and W7MP like this.
  7. W6MK

    W6MK Ham Member QRZ Page

    Ditto that motto.

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