Can AM Carrier Be Safely Turned Up On Newer Icom's ?

Discussion in 'Radio Circuits, Repair & Performance' started by W2BBQ, Nov 16, 2020.

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  1. G0GSR

    G0GSR Ham Member QRZ Page

    I have choice of two audio processors both with distortion cancelled limiters with almost zero overshoot.

    Even with a "perfect" limiter, once the signal passes through the radios filtering, the perfectly limited signal now has overshoots due to the severe group delay at each end of the filters passband.
    I have measured the filter group delay on the 7300 and its quite extreme. (As it is with any amateur transceiver). One of my processors does have some TX correction but not nearly enough to correct for the filters.

    I cannot be certain but it seems like on AM, the ALC voltage is fixed and there is another limiter (in DSP) to prevent overmod.
    At least, that is the effect I am seeing on AM.
    On SSB, the ALC is in control.

    Frank
     
  2. G3YRO

    G3YRO Ham Member QRZ Page

    Apologies for the thread hijack, talking about the TS930S . . .
    Well on my TS-930S there is NO difference between USB & USB on AM . . . it also doesn't seem to have anything limiting the audio frequency response (other than slight filtering in the Mic Amp)

    And there are SEVERAL errors in the '930 Handbook ! I haven't bothered trying to figure out exactly how the I.F. Filters are switched on AM Tx, as it's pretty complicated (and as I've said before, I would never use my '930 on AM anyway) . . . but I'm guessing only the board with the IF Can on it is in circuit on Tx (as used on AM Receive Wide if you haven't fitted an AM Crystal Filter).

    Roger G3YRO
     

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