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ALC high on the FT-450D

Discussion in 'Radio Circuits, Repair & Performance' started by N1QWI, Nov 19, 2018.

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  1. WA7PRC

    WA7PRC Ham Member QRZ Page

    . . . by controlling/limiting the drive LEVEL to the transmitter PA. That's the term MOST manufacturers of SSB xmtrs/xcvrs use.
  2. G3YRO

    G3YRO Ham Member QRZ Page

    Yes but the term Automatic Level Control says nothing about going into non-Linearity on the PA . . .

    The same with a Linear Amplifier . . . most develop an ALC voltage at the point where they start to become non-linear, and that control voltage can be fed back to the transmitter to reduce the drive.

    As far as I'm concerned, from the earliest days of SSB (and therefore Linear PA stages) ALC stood for Automatic Linearity Control . . . it's only later that the acronym has been mis-quoted to stand for Automatic Level Control (which I believe stems from the millions of cassette tape recorders produced in the 1960s. most of which had ALC, which in that case WAS Automatic level Control.

    Roger G3YRO
  3. WA7PRC

    WA7PRC Ham Member QRZ Page

    And yet (again), it directly controls the LEVEL (gain, actually), and that's what MOST people and SSB xmtr/xcvr manufacturers call it.
  4. SM0AOM

    SM0AOM Ham Member QRZ Page

    The term "Automatic Linearity Control" for ALC seems to be specific British usage, often found in the K W Electronics literature.

    ALC was introduced by Collins and had the meaning of "Automatic Load Control" in their earlier publications, but shifted to "Automatic Level Control" in later.

    Current usage at Collins is "Automatic Level Control", but as late as 1997 older instructors at the factory training about their solid-state amplifiers I attended spoke of "Automatic Load Control". Old habits die hard...

    WA7PRC likes this.

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