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swr on 6300 with amp

LarryLarry Member
swr reading on 6300 2:1 feeding the input to the amplifier buy 1:1 on external swr meeter between flex and amp.  I am wondering why that would be.  I can understand how the input of the map can be tunned off but on my FT 990 it is fine.  In addition the external watt meeter I have placed between the 6300 and the amp shows 1:1 so it looks like the swr in the 6300 is off.  The bypass is on on the ATU in the 6300 so the internal tuner is not on.  Any thoughts?


  • MackMack Member ✭✭
    edited March 2019

    Here is a sure fire test. Connect a dummy load with a short piece of coax directly to the radio. What does the SWR on the radio read now?

    Alpha Team
  • George Molnar, KF2TGeorge Molnar, KF2T Member ✭✭✭
    edited February 2019
    The length of coax between the rig and amplifier should be kept very short, or it will become something of an impedance transformer, particularly as your operating frequency increases. This could cause apparent VSWR readings to differ when measured at different points.

  • James SkalaJames Skala Member
    edited March 2018
    I also see that on the 6400 . My setup is the 6400 driving the spe 1.3 to the Palstar Hf Auto. All 3 read different SWR.
  • LarryLarry Member
    edited March 2018
    With the dummy load it is about 1.2 to 1  with the amp it is 1.5 to 1.  Maybe that is fine.  The cable length is very shot about the same length as on the 990 which is totally 1 :1 on the input to the amp.
  • MackMack Member ✭✭
    edited January 13
    Larry, Mystery solved. The Flex is really a high quality spectrum analyzer and reports with much more precision than other ham radios. When using it with your amp you can always turn on the ATU to touch up the SWR. Thanks for doing the extra check. Mack W4AX Alpha Team
  • KI4PKI4P Member ✭✭
    edited May 22
    well thought about that but the owners manual on the alpha says not to use radio tuner, says it uses wiring and relays in amp to match and possible relay or other amp failure. having same issue, with out amp on its good but with amp online its a little over two

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