Tuesday, March 19, 2024

QMX on CW: demo of thumping at the end of CW characters

A thread currently running on the QRP Labs group discusses the "thumping" issue on CW.

I received my pre-built QMX yesterday and was able to hear for myself how this it sounds on the 5 bands, 20 to 80 meters. As noted on the group, the issue is more pronounced on 80 meters and is present to a smaller degree on higher bands, although 40m seems the least affected.

The sound is the same whether using a powered speaker or headphones, and regardless of RF power out. Others on the forum note that it exists even when the output power is entirely disabled.\

There are numerous configuration settings possible in the QMX and some owners have adjusted AGC and other values to mitigate this sound. My values are all default except that I have made the sidetone volume track the AF gain by setting that value to 'Relative' from the default of 'Absolute'.

Hans G0UPL is prioritizing a fix for this issue.


.

.

6 comments:

  1. i hardly see anyone spotted on 80 Meters on the POTA spotting app. If the QMX is purchased with the idea of using it primarily as a portable ops radio, then 80 Meters is probably the least used of all the bands because of antenna requirements, anyway. Still toying around with purchasing one. 73 de W2LJ

    ReplyDelete
  2. Since you mentioned sidetone... (and you showed a picture of the (tr)uSDX, which leads me to believe you own one) how does the QMX sidetone compare to that of the (tr)SDX? TNX!

    ReplyDelete
  3. Thanks for the "thumping" demo. Definitely NOT a deal breaker, when the rest of the rig's capabilities are considered.

    ReplyDelete
    Replies
    1. I'm hopeful that the sidetone issue will be resolved but it's fine with me as is since I don't get on 80m anymore. The other bands are ok for quick POTA-type ops. For those who are more into ragchewing on CW, I can see how they'd be anxious for this to be corrected. I'm surprised the issue exists this far into the QMX development.

      73,
      John

      Delete
  4. I can shure hear the difference between 80/60m. 80m would me almost unworkable that way. I'm shure there will be a fix in no time. Very nice small radio btw. And from what I hear I make progress. As far as I can hear you're sending VVV TEST :-). I'm certain I would not decode that last year without the use of a computer. What brand of keyer do you use? I'm shure you've noticed it somewere on your blog. 73, Bas

    ReplyDelete
    Replies
    1. Hi Bas,

      Congrats on your CW progress! Yes, VVV TEST and some gibberish! The paddles are from 9A5N:
      https://www.9a5n.eu/models.html

      They are solid state - no movement of the paddles at all. Keying with them took a bit of "getting used to" but I like them very much. BTW, these are only paddles - I still need a keyer, in this case, it's the built-in keyer in the QMX.

      73,
      John

      Delete