Problem Using DAX Channel 1 with Flex-6500

  • 1
  • Problem
  • Updated 4 years ago
  • Acknowledged
Today, I tried to use my Flex-6500 with both K9DUR's Voice Keyer and with N1MM+ Voice Keyer. In both instances, I initially used DAX Audio TX 1 to send messages to the radio (K9DUR) and for Playback in N1MM+ (Logger + Audio Setup). DAX 1 was properly selected in SmartSDR 1.3.8 and the DAX button was blue in the P/CW section. 

Using both K9DUR's Voice Keyer and N1MM+, I could activate PTT and I could see something being transmitted on the panadapter. However, while listening on another receiver, what I heard was a strong pulsing signal with no modulation. In the DAX Control Panel, even when I was NOT transmitting anything, the TX Gain for DAX 1 was almost at maximum scale. Since I was not transmitting, there should have been no signal present in DAX 1 TX Gain. 

I closed and re-opened DAX, exited SmartSDR, and shut down the Flex-6500 and computer for several minutes at a time. I did this whole routine several times. Still, in the DAX Control Panel, even when I was NOT transmitting anything, the TX Gain for DAX 1 was again almost at maximum scale.

My solution - I changed everything so that I was using DAX Audio TX 3 in SmartSDR, K9DUR's Voice Keyer and in N1MM+. Everything worked properly using DAX 3. I can send using both K9DUR and N1MM+ Voice Keyers and I can hear over my second receiver that I am transmitting a clean and intelligible signal. I suspect things would work just fine using DAX 2, DAX 3, or DAX 4. The culprit is DAX 1.

My problem - DAX Audio TX 1 seems to be generating a strong pulsating signal of some kind even when I am not transmitting. The same behavior is NOT present on the other DAX channels (2-4) with my Flex-6500. 

Any suggestions as to why my DAX Audio TX 1 is generating this continuous TX signal? Have I done something stupid that created this problem?
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Gary Robertson - KY5R

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Posted 4 years ago

  • 1
Photo of Tim - W4TME

Tim - W4TME, Customer Experience Manager

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We are aware of this issue and several other DAX issues that we are working on for SmartSDR v1.4.  I Cannot guarantee the changes will fix all of the DAX issue, but we have put a lot of effort into making it more stable and reliable.
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Gary Robertson - KY5R

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Thanks Tim. Another demonstration of excellent customer service. I look forward to v1.4. Hopefully this DAX problem can be resolved.
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Doug K0DV

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One serious limitation is that DAX can only use one channel at a time.  Operating remotely, I cannot operate split since each slice must be assigned a different DAX channel. if I assign the the TX of the split to slice B and select a different DAX channel than slice A, the channel does not work. Perhaps this will be fixed with the local LAN remoting capability.  I have missed many DX opportunities because the Flex 6700 cannot use two DAX channels simultaneously for split operations.
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Ken - NM9P, Elmer

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I have used RTTY split quite effectively up to 5 KHz simply by using the XIT.  Splits larger than that are more troublesome and require using two slices, which can be made to work if you use one DAX channel on 'A' and another DAX channel on 'B' and set your DIGI program up so that the RX and TX in/out use those two different DAX channels.  But it makes it harder to go back to simplex....... Perhaps this trick only works locally?  I have not tried it with remote operation.
(Edited)
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Cedric HB9HFN

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Doug is right. I hope FRS will come with a good solution for this limitation...
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Mike - N1MD

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Frankly, I am tiring of the XIT work-around for the DAX split limitation. I have tried the dual channel approach using my digital programs but it is very clunky and not conducive to enjoyable digital DXing. For me, this is the ONLY disappointment I have experienced with SSDR and my 6700. I look forward to some imaginative engineering to get this aspect of DAX fixed at the proper time in SSDR development.
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Ken - NM9P, Elmer

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Perhaps they could devise a way to select a slice's RX and TX DAX line separately, just as we are able to select RX & TX antennas separately?
(Edited)
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Doug K0DV

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One other problem I have with DAX is that once I connect with Skype, the RX audio sent by the Flex is very low. To fix this, I have to cycle the DAX channel being used in the DAX interface.  Then the audio picks up to normal level.  However, it often starts to annoyingly flutter (perhaps the pulsing) to which Gary refers.)  To fix this, I have to cycle the DAX channel again. The problem however, comes back in a few minutes requiring another cycling of the channel. When I was using VAC with the Flex 5000, I had none of these problems.