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Can 6600M's NR compete with Yaesu FTdx101 com?D

I received a 6600M yesterday and was flabbergasted with its poor DNR compared with my Yaesu FTdx 101d. Baseline noise remains at S5 no matter what I change. Any ideas on how to improve this issue? Other than this issue, I really like the radio compared with Yaesu!


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

    Any DSP functions are applied in the FlexRadio receive chain after the S meter calculations are made. This mains any changes you make are not reflected in the S Meter. By definition, S Meter values are used to measure RF Energy at the antenna port.

    In the over 100 year old designed SuperHet radio design (not kidding :) ), the S Meter is part of the final ALC circuit, so any DSP functions are generally made before the S Meter calculations. The S meter is part of an AC to DC rectification to produce a DC voltage that causes the S meter to move.

    In order to really make the measurement you are trying to achieve, is there an improvement in SNR (Signal to Noise Radio).


  • tomblasco
    tomblasco Member ✭✭
    Thank you! Forgetting about the 'S' meter, the SNR is still well below the Yaesu. I have tried maximum NR, all parameters of the AGC, NB, WNB, etc. Only a limited reduction in the background noise occurs.
    Any suggestions? I still very much like the radio's simplicity and versatility. Thanks again for your help. tom KD9QHX
  • Mike Steventon
    Mike Steventon Member ✭✭✭

    I have noted that I get the best NR by doing something to the incoming signal before it hits the Spectral Capture Unit. I have recently been experimenting with a DX Engineering NCC-2 signal Phasing unit and an active magnetic loop “noise” antenna at port two, together with my good old trusty half-wave inverted L end-fed (very noisy!) for 40M at port one. I have been amazed at the very considerable improvement in signal-to-noise ratio audio coming out of the speaker. Sure, it does take a bit of twisting and fiddling with knobs and such-like, which is all part of the fun, and also mucking about with rf-gain, but the result is little short of fabulous. My S meter readings before fiddling are anything upwards of S7 on 80M and 40M with just the main antenna. Now, I am seeing S2-S3!! BUT, I cannot give the other end a 5-9-9 report, as the level gets carried down the “S” meter somewhat, with the adjustment. What I can say, though, is that the intelligibility and clarity is vastly improved, which frankly is all that matters, and I do not seem to lose anything in the way of other station transmissions across the band in use.

    I also have noticed that setting the AGC-T carefully pays off dividends. And also investment in a couple or so of decent common-mode-chokes at the entry point to the 6600M has also paid off well in knocking out undesired noise pick-up from feeder/co-ax.

    I do not know if it is possible to arrange for the Flex SSDR to show real-time actual SNR as does happen on SDR-uno? Perhaps that could be a useful addition on future update? That way, one could then see the difference you can make with antenna choices etc. etc.

    Trial and error will win out the day!!

    73. Mike.

  • tomblasco
    tomblasco Member ✭✭
    I just received a Ciro baby loop magnetic antenna. I will be installing it in a month or so. With its very high Q and directionality, this should reduce a lot of the noise. If that doesn't improve the SNR sufficiently, I will likely consider the NCC-2 with a good receiving antenna(s). Thanks for the timely response. Tom KD9QHX
  • BG5ILX
    BG5ILX Member ✭✭

    Adjusting the MED with heart has a very good effect, I hope it can help you

  • Hal Massey
    Hal Massey Member ✭✭

    One thing to keep in mind with a Flex is that there is a sequence to applying noise mitigation features. Flex has a great video on this you may want to checkout. It's not like the J-radios many of us are used to (myself included).

    I also own a 6600M here at home and 2 6400's that are in remote service.

    73 / WB6NNR

  • tomblasco
    tomblasco Member ✭✭
    Thank you! I am impressed with the communities support. Tom KD9QHX
  • K9YK
    K9YK Member ✭✭
    I have a 6400M and a FTDX-5000MP. No amount of AGC-T and NR on the Flex can reach the quietness of the FTDX-5K receive (and I only ever use the 5K NR on level 1). Also the Flex NR introduces more artifacts to the receive audio. It’s disappointing on the part of the Flex.

    The only area I’ve found so far with the Flex that I prefer over the FT5K is the wide band noise blanker. For power line noise, it is simply magic. So far I’m sticking to the FT5K for HF and using the Flex for VHF/UHF only.

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