Valiant and other clipper circuits: The magic, the mystery, and the scorn

Discussion in 'Amplitude Modulation' started by N1BCG, Jan 17, 2021.

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  1. N1BCG

    N1BCG Ham Member QRZ Page

    Funny you should mention this. My Valiant is driven with a Hnat-Hindes CSP-2013 wideband compressor/clipper (with B'cast mods per the manufacturer). The audio is inserted at the grids of the 6146s using a 600:8,000Z CT transformer.

    I was actually thinking of running the Class E transmitter with just a clipper + LPF circuit, possibly tonight. Just need to set up a bal/unbal interface and be very mindful of mic gain.
     
  2. W2VW

    W2VW Ham Member QRZ Page

    Well Clark you are safe for now. I couldn't get on the air as the tower was nested due to high winds.

    I was going to listen to a Hendrix CD during my 45 minute cardio workout but chose to listen to you guys instead. I figured you would have better harmonic content.

    Alas the Valiant clipper was not in use.
     
  3. K5UJ

    K5UJ Ham Member QRZ Page

    Is that the Mic Maze?
    That mental state seems to especially affect certain Collins owners. Art was a genius, Collins stock, is perfection, any non-factory mods an abomination.....
     
  4. N1BCG

    N1BCG Ham Member QRZ Page

    Yes, with the Steve Hnat mods for AM which drive the compressor and clipper harder in addition to modified pre-emphasis and LPF values.
     
  5. W2VW

    W2VW Ham Member QRZ Page

  6. K4KYV

    K4KYV Premium Subscriber Volunteer Moderator QRZ Page

    One problem with the crude Valiant type clipper/filters is phase shift in the stages that follow, mostly occurring at the "value engineered" driver and modulation transformer, and at the low-pass splatter filter following the clipper stage. This causes the flat-topped clipped waveform to "cant" or tilt, so that the crest of the peak resembles a sawtooth waveform instead of a square wave. This tilt increases net modulation percentage and thus the peak-to-average ratio, partially negating much of what the clipper was supposed to accomplish.
     

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