LDG AT-200 Pro-II Tuner

[last updated: 2025-04-01]
ham radio home page
-----

• Basics:
  This unit adds series inductance and parallel capacitance to the antenna signal path.

• Operation tips:
  • Function Mode:
    • The Function mode allows setting several options to your/user preference.
    • The procedure is to enter Function mode, then press desired setting key.
      This must be done while NOT transmitting.
    • Enter Function Mode by pressing momentarily and releasing the Func button.
      The LED bar graphs will flash in an "up-arrow" configuration to indicate you have entered Function Mode.
    • Function Mode will automatically time-out and exit after about 5 seconds,
      after which the LED bar graphs will flash in a "down-arrow" configuration.
    • Alternatively, you can manually exit Function Mode by again pressing the Func button while the mode is active,
      and the LED bar graphs will flash the "down-arrow" configuration to indicate that you have exited Function Mode.
      ------------------------------------------

    • While in Function Mode:
      • The PWR LED bargraph can be set to display either average or peak power.
      • The PWR LED bargraph full-scale value can be set to either 25 or 250 watts.
      • Set full-auto tuning SWR threshold: (see below)
        The SWR threshold can be set to 1.7, 2.0, 2.5, or 3.0
        Press L-down while in Function Mode. This will increment the threshold one step.
        The new value will blink on the SWR bargraph.
        You must again press Func -> L-down to increment another step.
        At threshold of 3.0, pressing Func -> L-down will return to 1.7.
      • Auto-tuning mode can be set to either semi- or full-auto tuning:
        • Press C-down when in Function Mode to toggle between them.
          If you have selected semi-auto tuning, the LED bargraphs will blink LED's at the far right and far left.
          If you have selected full-auto tuning, the LED bargraphs will blink LED's in the center.
        • Semi-auto Tuning:
          In this mode, a tuning cycle will only happen if the Tune button is pressed.
        • Full-auto Tuning:
          In this mode, a tuning cycle will happen any time the SWR exceeds a threshold (see above).

    ------------------------------------------

  • Bypass:
    In bypass (bypass LED will be lit), the tuner is 'out of the circuit',
    and RF signal from your transmitter is passed through to the LDG output without adding any L or C.
    To toggle between bypass or not,
    Press momentary and release Tune button
    The bypass LED may also be lit if all tuning elements (L & C) are at zero

    ------------------------------------------

  • Current Tune values (L & C):
    While NOT in bypass,
    Press and hold Func button, press and release Tune button
    Current state of tune will be indicated on LED bar graphs as long as you continue to hold the Func key.
    Each row of LED bar graphs (PWR & SWR) has 8 LED's.
    Only 7 of them are used for tune value indication (far right LED has other functions).
    The pattern of lit LED's indicates the numerical value of the currently programmed L and C state, in binary.
    That is, the left-most LED is "1", the next "2", and the 7th is "64"

    Top row ("PWR") LED bar graph is  L,
    Bottom row ("SWR") is   C.

    Note this is contrary to what the manual says, which is that the PWR/top row of LED's indicates C (capacitance)
    However when you manually tune by pressing C or L up/down buttons, in fact the top/PWR bar graph is changed when using the L-up/down buttons.
    OTOH it may be that the up-down buttons are the ones that are mis-labeled, so who knows...

    ------------------------------------------

  • Tuning:
    • Manual Tuning:
      • Pressing L-up/down or C-up/down will manually adjust the L & C values in your current state of tune.
    • Tuning Cycle:
      • A tuning cycle can be initiated in any one of three ways:
        • Pressing the Tune button
        • An over-threshold SWR value while transmitting in full-auto-tuning mode.
        • Pressing the Tune button on your ICOM transmitter when connected with an interface cable.
      • Pressing Tune button on tuner:
        • If you do NOT have an interface cable to your transmitter:
          • You MUST manually reduce your transmit power to 5 - 10 watts.
          • It is also polite to dial to an un-occupied portion of the band.
          • Set your transmitter to FM or CW mode.
          • Key and hold transmitter on.
          • Press and hold LDG Tune button for one second, then release.
            Continue to hold transmit PTT until tuning is done.
          • Relay clicking should happen.
          • When tuning cycle is complete, LED bargraph will blink pattern ...

    ------------------------------------------

.

eof