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Automatic Tuning Unit

Does the Flex 6000 series Automatic Tuning Unit work in the Receive mode ? 73's , Bruce - KL7JDR


  • George KF2T
    George KF2T Member ✭✭✭
    edited February 2019
    Yes, it does. Currently only ANT 1 is supported for TX, therefore ATU, also.
  • W5XZ - dan
    W5XZ - dan Member ✭✭
    edited June 2019
    also, the ATU does not seem to tune on CW; if you switch to SSB, it WILL tune, and seems to stay tuned when you switch back to CW...known bug in xx.17 i think..
  • Tim - W4TME
    Tim - W4TME Administrator, FlexRadio Employee admin
    edited December 2016
    This is a great conversation that's separate from the main topic, so I created a new "Report a Problem" topic to continue the discussion. Please reference the new topic here: ATU does not tune in CW mode
  • Carl/K5HK
    Carl/K5HK Member ✭✭
    edited August 2014
    ATU tunes fine in CW if the Tune button is selected prior to hitting atu but tune must be manually turned off after tuning. Carl/K5HK
  • Steve-N5AC
    Steve-N5AC Community Manager admin
    edited February 2017
    The ATU is located on the PA board in the radio and, when enabled, is inline with either ANT1 or ANT2 (depending on which antenna was used for tuning). The transmitter is required to initiate the tuning algorithm in the ATU. Once the ATU has been tuned and it has been selected (ensure that the tune was successful and the ATU is not in bypass), it will also be in line with the receiver for any slices or panadapters connected to the antenna that the tune was initiated on. So the ATU does work for receive also, but only for the antenna selected when the tune was initiated. Steve
  • W5XZ - dan
    W5XZ - dan Member ✭✭
    edited June 2019
    so, under ...17 software, 'tune' should be backed off to ?? 10 ?? i HATE hot switching good relays, dude...
  • Steve-N5AC
    Steve-N5AC Community Manager admin
    edited December 2016
    For the ATU, we reduce the power out of the PA down to around 10W (sometimes lower). This is a low power level and we've had no issues related to switching antennas at this power level. Steve
  • W5XZ - dan
    W5XZ - dan Member ✭✭
    edited December 2016
    under xx.17 software, i BETTER turn TX drive down from 100%, huh ?? NOT default....
  • KB5XE
    KB5XE Member
    edited April 2020
    Steve, my 6700 with v.0.15.13 does not tune on 20M. Always reverts back to by-pass. Problem reported or just me. Owen KB5XE
  • Steve-N5AC
    Steve-N5AC Community Manager admin
    edited December 2016
    The tuner measures the SWR before and after a tune and makes decisions about the right final setting. If you have a 1.1 SWR before the tune and a 1.2 after because switching in any additional components yields a worse match, it will revert back to bypass after the tune to give you the best SWR. Do you think this is what is happening or do you have a poor match on 20m? Steve
  • Reggie-k6xr
    Reggie-k6xr Member ✭✭
    edited July 2016
    I have two radios and auto tuners that tune my antenna 3.5 to 52mhz 1.1. My flex 6500 will not tune anywhere 3 of the bands. so I am using a ldg for tuner.
  • W4EG
    W4EG Member ✭✭
    edited June 2018
    Check your antenna... You have a high SWR... and the ATU will not tune that frequency. I seen this on160 meter... however, when I go to higher frequency. It works like peanut butter and jelly. SWEET!
  • Grump
    Grump Member
    The Flex Auto antenna tuner. Is it a roller inductor and plate capacitor construction driven by stepper motor or is it lumped constants?
  • VE7ATJ_Don
    VE7ATJ_Don Member ✭✭✭

    Given the relay sounds heard when it is engaged to find a 'solution', I would suspect the latter. I suspect it is very similar in design to the ATU's found in most transceivers these days.

  • Gord-VA7GP
    Gord-VA7GP Member ✭✭

    It is lumped-components.

    Same as my 1992 TS-850 from 30+ years ago... these built-in tuners have limited volume to work with, and toroids keep the fields tight (without coupling to everything). You get a functional tuner, but with limited range, limited power.

  • John KB4DU
    John KB4DU Member ✭✭✭✭

    The internal tuners in almost all rigs are lumped components due to size limitations. This also limits the range to about 3:1.

  • Mike-VA3MW
    Mike-VA3MW Administrator, FlexRadio Employee, Community Manager, Super Elmer, Moderator admin

    All HF radio internal tuners are designed to extend the range of an already resonant antenna, or about 3:1. There are exceptions, but it really depends on the antennas reactance.

    It is correct called an Antenna Matching Unit.

    External ATU's can cover a broader range.

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