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What is the maximum suggested power for RTTY mode with the Tuner Genius XL?

I've read the documentation on the tuner and understand that the power rating is 2,000 watts ICAS. The question is: in a constant carrier mode such as RTTY, is there a suggested maximum power not to be exceeded? A discussion of ICAS vs. CCS is not necessary. I ask this because the Palstar auto tuner, rated at 1,800 watts ICAS, cannot safely be used at above 375 watts in a continuous carrier mode. I know that the characteristics of the antenna used will affect the maximum power. What I want to know is what is the limit that it would be unwise to exceed with a constant carrier mode? Thanks.


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

    ICAS, or Intermittent Commercial and Amateur Service, refers to a rating used primarily for amateur radio transmitters.

    In simpler terms, ICAS transmit power is the level of power a radio transmitter or amplifier can safely handle for short bursts or intermittent use, rather than continuously. This rating is particularly relevant in amateur radio because transmissions are typically not constant; operators often transmit in shorter bursts, either for voice communication or data transmission.

    For instance, a radio amplifier might have an ICAS transmit power rating of 1500 watts. This means it can handle transmitting at 1500 watts in intermittent bursts, but it may not be capable of sustaining this power level continuously without overheating or experiencing other issues.

    100% ICAS" refers to a transmitter or amplifier's ability to operate at its maximum rated power under Intermittent Commercial and Amateur Service (ICAS) conditions continuously without overheating or degrading its performance. Essentially, it means that the equipment can safely handle its top power output (as specified in its ICAS rating) in a continuous, non-stop manner, which is somewhat contrary to the typical intermittent nature of ICAS-rated operations.

    It implies that the equipment is robust enough to handle prolonged periods of operation at its maximum power without any reduction in performance or risk of damage. This is particularly useful for scenarios where extended transmission at high power is necessary.

    However, it's important to note that even though a device might be rated for 100% ICAS, this doesn't mean it can be operated at full power indefinitely without proper cooling or ventilation. Continuous high-power operation still generates significant heat, and adequate cooling systems are essential to maintain the equipment's integrity and performance over time.

  • Floyd Sense
    Floyd Sense Member ✭✭
    Yes, I understand all that. The question is simply: what is the maximum amount of power your tuner can handle on a constant carrier mode such as RTTY for a reasonable period of time? Maybe that is 10 minutes? I understand why Flex might not want to commit to an answer to that, that's why I asked the question here where I thought some actual users might be able to tell me what they've experienced. I've owned other auto tuners that whose power ratings were described just as your is, and watched them go up in smoke in RTTY contests running 800 watts or so.
  • Floyd Sense
    Floyd Sense Member ✭✭

    Since there has been no further information on the question, my plan to buy the tuner is cancelled.

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

    The answer you are looking for is not so simple. It does depend on the antenna and the tuning solutions that are required to provide a 50 ohm load to the radio.

    If you were using an End Fed Half Wave, I would not run 1500 watts for 10 minutes.

    There is a derating table in the user manual.

    However, the TGXL is pretty smart. When you first tune, there is a Red Bar that shows up showing the max ICAS power limit. It determines this value based on what it does to analyze your antenna.

    If you go over the power limit as determined by the TGXL, the TGXL will then go into the bypass and drop out of line.

    This will present a high SWR to the exciter, which will then be handled by the exciter and they do a power foldback.

    This is why you connect the PTT OUT from the TGXL to the PTT in on the exciter.

    tldr; the TGXL has the smarts to protect itself.

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