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Why do I have to re-tune the ATU when I change the receive antenna?

Robert -- N5IKDRobert -- N5IKD Member ✭✭
edited March 2017 in FLEX-6000 Signature Series
Why do I have to re-tune the ATU when I change the receive antenna?

If I tune an either ANT1 or ANT2, then switch the "receive" antenna to the other antenna ANT2 or ANT1, then my SWR reading increases until I re-tune. Is this the correct behavior?

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  • K6OZYK6OZY Member ✭✭
    edited February 2017
    Persistant ATU memories are a coming feature.    The default behavior is to disable the ATU on antenna switches between ANT1/ANT2.   Mentioned here:  https://community.flexradio.com/flexradio/topics/vswr
  • Robert -- N5IKDRobert -- N5IKD Member ✭✭
    edited March 2015
    I am only switching the receive antenna. Isn't the transmit antenna the one that is tuned?
  • K6OZYK6OZY Member ✭✭
    edited June 2014
    I would think so, but it does it when the RX antenna is changed too.   I just reconfirmed this on my 6700.
  • pa0biepa0bie Member
    edited June 2014
    After the ATU is used , the receiver is also working through  the tuner as I have understand.
  • Tim - W4TMETim - W4TME Administrator, FlexRadio Employee admin
    edited March 2017
    Robert, the ATU is working as designed.  The ATU, when enabled is in the RX and TX signals paths.  So changing any antenna in any slice will put the ATU into bypass mode and require a re-tune. Granted on RX this really doesn't make a lot of difference, especially in the same band, but for TX, it makes can make a significant difference.

    Once we add the automatic / memory feature for the ATU, this behavior will be mitigated as if you have previously tuned it, the LC combination for that antenna port/frequency combination will be in a memory and will automatically be selected. 
  • K6OZYK6OZY Member ✭✭
    edited June 2014
    Tim, is the only choice to be inline for RX & TX?   I would prefer it to be inline for TX only.
  • Tim - W4TMETim - W4TME Administrator, FlexRadio Employee admin
    edited December 2016
    This capability is not under software control. 
  • Andrew VK5CVAndrew VK5CV Member ✭✭
    edited February 2017


    With 1.4 I am now using a Pixel loop on RX A.

    When I change the RX antenna to Ant A (or back again) the TX ATU drops out and I need to retune.

    I know that memory tuning is coming but it seems to me that the ATU should follow the TX antenna.

    Andrew VK5CV

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