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ACC Input Level

Mark Erbaugh
Mark Erbaugh Member ✭✭
I think I asked this once before years ago, but I can't find the thread.

I am trying to drive the line input on the 15-pin ACC port of the 6700, with a USB soundcard (actually, a Timewave Navigator interface). According to the specs, the output level is 410 mV into a 4.7 kOhm load. The most input level I can show on the 6700 is under -10dB, which isn't enough to drive the transmitter. I think the difference may be due to the fact that the line in is set for Pro audio at +4dBV instead of consumer audio at -10dBV. Is there anything I can do to increase the line in gain?  FWIW, the line output signal work fine into the Navigator's soundcard.


  • Mark Erbaugh
    Mark Erbaugh Member ✭✭
    edited February 2020
    Okay, I reread the documentation and it appears that the line in is actually consumer level at -10 dbV. I used my scope to measure the signal coming from the Navigator and it is +/- 600 mV which seems to be within the consumer output level. Why am I not able to drive my Flex transmitter?
  • K0FLY
    K0FLY Member ✭✭✭
    edited July 2019

    Hi Mark:

    One thing that I found is that the FLEX “EQ” settings APPEAR to set the drive to the transmitter in the SSB mode (note appear).

    When I got my first FLEX 6K radio, I set the EQ up so that no slider was above the  0 dB line.  I received poor signal strength reports even though the peak reading watt meter was indicating 100 watts .  In fact my Winged Emblem S-Line would out talk the FLEX.  I had to run the audio level indication on VU meter into the red to get the talk power up to the level the S-Line. 

    I finally solved this by increased the EQ sliders by 4 or 5 points, up came the  average power, with the FLEX VU meter indicating around -10 dB.   I run the “PROC” in normal and set the levels so that I the compression meter indicates a small amount ( no more than 5 dB on peaks).   I do not like a lot of compression.

    If you’re running an external EQ, try enabling the Flex EQ with sliders set at ‘FLAT” but increase the all of the sliders above the zero line.

    Give it a try, hope this helps. 

    AL K0VM runs a similar set up as you are trying, maybe he will chime in here with some words of wisdom.

    Gayle K0FLY

  • Mark Erbaugh
    Mark Erbaugh Member ✭✭
    edited February 2020

    Thanks for the reply. The EQ does seem to help in SSB (LSB) mode, but not in DIGL. I suspect that the equalizer is bypassed in digital mode.

  • Mark Erbaugh
    Mark Erbaugh Member ✭✭
    edited February 2020
    No update from Flex.

    Is anyone successfully using the ACC input with consumer level audio? Is anyone successfully using it with Pro level audio?
  • Bill Wuttke KE3BK
    Bill Wuttke KE3BK Member ✭✭
    edited June 2020
    I'm running 2.6.2 with a 6400M and the problem still exists. Even though the ACC ports were supposedly designed for external TU's and modems, the only way the ACC Line In port will meet spec of -10 dBV is with the TX EQ cranked up 10 dB USB/LSB only. Virtually all TU's specify a max output level of 0dBm, (approx. 0.77VRMS). Without any EQ, it takes approx. 1.7 VRMS to drive the radio to full power. Is there still an open ticket on this?

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