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I have been tempted by one of these second hand good price, but am not sure I would be wasting my cash? My 6600M has eq, gain,compression, essb, downward expansion already built in. The only extra I can see is adjustable delay on the W2IHY, and possibly a limiter… Still on the fence with this one. I use Heil PR 40, and seem to get good reports. The gain is quite good using the built in pre-amp +20dB so no problems with driving the main output.

If it goes before I decide, then too bad!!!

73 de Mike


  • David Decoons, wo2x
    David Decoons, wo2x Member, Super Elmer Moderator

    I use the 8 band EQ and EQ Plus for years with various radios. My mic of choice is the Electrovoice RE-27ND but have used the PR40 as well.

    I get great audio reports when rag chewing on 80 meters (4 KHz bandwidth in extra portion of band where we’re are not interfering with people below us). For DX I just change TX bandwidth to 150 - 3000.

    If you buy one new from Julius he has a great return policy. If you buy a used one at a great price you can always sell it and at least get your money back. They are in demand.

    I find the preamp in the 8 band EQ or EQ Plus is better than the 20 dB preamp in the radio.

    Dave wo2x

  • Mike Steventon
    Mike Steventon Member ✭✭✭

    Thank you very much Dave for your input. I know they are very popular, so yes, I suppose that if I do not get on with it, then I can move it on and let someone else have a go. There are many conflicting reviews and reports on the equipment, with mostly favourable remarks. It just seems daft at first thoughts when I have spent so much on a superlative radio, and it seems almost rude to start sticking things in front of it to improve on the "best"!

    I shall quite probably take the plunge, because if I don't try it I will not know, and it will bug me for the rest of my life. It's only money, and you can't take it with you.....

    73 de Mike G4GWH

  • David Decoons, wo2x
    David Decoons, wo2x Member, Super Elmer Moderator

    My take is the PR40 and RE27 need a preamp. The one in the W2IHY equipment I feel is better than the +20 dB preamp in the radio. (Cleaner audio, better s/n. ). The downward expander in SmartSDR is good up to about a level of 45. After that, you can hear artifacts on the transmit audio. The newer designed EQ Plus with the EQ Plus downward expander enabled has some DE action, even with the knob fully CCW.

    I run the radio processor on and normal. Radio DE at 40. Then EQ Plus compression at 8:30 position and DE knob fully CCW. This mitigates background noise from the amp to where it is not objectionable but still audible. If you adjust it to eliminate background it clamps up the audio where you can hear “edges” on the tx audio syllables at low speaking volume.

    I have, and use an Inrad DMS629 full range mic for Field Day and other times I bring the radio portable. It works well matched up to the radio with no outboard gear. Is it as good as the RE27 with W2IHY gear? I don’t think so based on recordings I’ve heard but it is a lot less expensive.

    Others may chime in with their thoughts. As I stated, I have been using Julius’ gear with a LOT of radios, going back to the Flex 5000 and Yaesu FT2000.



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

    I have a number of friends using the UR6QW series.


  • Mike Steventon
    Mike Steventon Member ✭✭✭

    Some very interesting remarks. Thanks. I have checked out the UR6QW videos. It appears to not be available retail in the UK, but that was on a quick search on google.

    i could well be wrong, but it would appear on inspection that the UR6QW does not offer balanced mic in or out. I like to choose balanced input to the 6600M, as I have been conditioned(!!) to expect best results from balanced audio chain. The W2IHY kit I believe, has balanced in/out, if you use the two units together, and use a non-yaesu/kenwood/icom mike. There is a three-pin input on the EQ Equaliser (balanced) and the manual for the EQ Plus shows balanced output on pins 1 and 2 of the 5-pin output, which I would then feed into the 1/4” TRS at the rear of the 6600M.

    Yes, Dave, I have had a few reports of artifacts breaking through my transmission due to the SDR Downward Expansion being set too high, but I would put myself to blame for bad operating!!

    What has kicked all this off is that now I can see the waterfall display, I have become jealous of some transmissions that appear to have a full content, or very nearly, across the 3khz bandwidth, and the sound is fantastic. Their QRZ.com pages usually indicate major works going on in the audio chain before it even hits the rig itself.

    Just more food for thought, and hope it helps other readers.

    73 de Mike G4GWH

  • John KB4DU
    John KB4DU Member ✭✭✭✭

    I wish someone could explain the advantage of balanced mics in ham radio to me.

    In my previous life in tv, fm, and audio production, balanced mics were used to reduce hum/noise pickup in long mic lines, but loss and frequency response weren’t any different than unbalanced, which we used during remote broadcasts

  • Mike Steventon
    Mike Steventon Member ✭✭✭

    An excellent point of view. I read the manual and observed this:


    7.3.4 Balanced Audio Input (FLEX-6600, FLEX-6600M Only)

    This is a balanced audio input for the radio and will produce the highest quality audio transmission. It can be used as a microphone level input only. It is not suitable as a line level input. It accepts a 1⁄4” (6.3mm) TRS Phone Plug. Refer to section 21.4, How to Configure the Audio Controls for Phone Modes, for information about selecting the microphone for use.

        TRS Connector





     Positive phase for balanced mono signals or mic (+)


    Negative phase for balanced mono signals or mic (-)


        Ground or shield connection

      To prevent ground loops and RF ingress into the microphone circuit, the MIC (-) wire should be connected to the Ring and NOT to the Sleeve, the chassis ground. The circuit is wired as a true differential input and can thus be used with balanced microphone or line input.


    I put my faith and trust in Flex, so have I been “white-washed”?

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