Most Common Fix for DAX Driver errors in Windows Spring Update (1803) (You can do this!)

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As we continue to see high ticket rates related to the Windows Spring Update (often referred to as 1803), we can better recommend actions for our customers to take for fixing the problems.

The Most Common Problem

The most common problem is that the DAX Sound Device names are being mangled during the Spring Upgrade. The diagram below shows what a correct configuration of DAX should look like in the Device Manager:

After the Spring Update, here is what happened to one of my computers:

To list the problems with my installation, highlighted by the boxed entries, we find:
  1. We are missing 2 DAX IQ devices, that are present in the correct list. These are DAX IQ RX 2 and DAX IQ RX 4. Some of the mangled named devices are actually these two devices.
  2. We are missing 2 RESERVED IQ RX devices, DAX RESERVED IQ RX 2 and DAX RESERVED IQ 4. Again, some of the mangled named devices are actually these two devices.
  3. This system is one that I use PowerSDR on to test my Flex-3000 and use Virtual Audio Cables. You can see two of the VAC cables have been mis-named to DAX Audio TX and DAX MIC Audio.
Let's Fix This System!

If you see many multiple devices with the same name, feel uncomfortable in doing this procedure or just cannot figure out what to do, STOP! Create a trouble ticket and let Flex Technical Support work on your system.

Before we begin fixing these issues:

  1. Terminate SmartSDR and DAX. I know it sounds simple but I usually forget to do this! Double-check before you begin.
  2. Defeat your antivirus and malware software (as much as you can) during this process. Sometimes they will 'sandbox' these actions so they appear to be fixed but once you reboot, no changes are made.

To fix these, I will first right-click on the DAX Audio TX device that is a Virtual Audio Cable and select Uninstall Device. I will get the warning below, but will accept the risk and click Uninstall.

I will repeat this action for DAX Mic Audio device.

To fix the remaining items, I will open the Sound control panel app. When the Sound window opens, right click on it and you will see two items that are usually checked, 'Show Disabled Devices' and 'Show Disconnected Devices'. Uncheck them so we do not see these devices in our list (it will only confuse things!).

Now, click on the Playback tab in case it doesn't automatically open and scan for the name of the first erroneously titled device, which is DAX RESERVED AUDIO RX 2 which has the descriptor 'FlexRadio Systems DAX IQ'. Here you can see two of the mangled named devices in this window:

I will double-click on DAX RESERVED AUDIO 2 and see the property page below:

You notice that the device name is highlighted. I can now rename it to the proper name. Since I am missing a device that should be titled DAX RESERVED IQ RX 2 and this partially matches this device, I will assume its the one I am missing and rename it.

Press Apply, then press OK. You probably only need to press OK but I am a guy who wears belts and suspenders!

Look thru your list and see if any other devices are present that are mis-labeled. If so, repeat this procedure. You will see that the named device is partially correct, you only need to fix the part that isn't. I had a device called DAX RESERVED AUDIO RX 2 and renamed it DAX RESERVED IQ RX 2, for instance.

While you are in this window, make sure no DAX device is designated as the defaul playback device (green cirle with a white check-mark). If so, find the device for your speakers or headset and right-click on it, then select Default Device.

Now, click on the Recording Tab and perform the same action. By the picture below, I found DAX Audio RX 2 that is labeled as an IQ device:

Based on our approach from before, double-click it and rename it to DAX IQ RX 2.

Press Apply and OK and you have fixed another one!

Repeat for all the other misnamed devices you discovered in your examination of the Audio Inputs of the Device Manager.

Now, you have to reboot your system. If you do not, it will not work!

Once you reboot, go to the Device Manager control app and look under audio inputs and outputs, comparing it to the first picture above. It should be identical. If not, try the process again (we have had one customer report it took two tries to work on his system). After that, if it doesn't work, contact Flex Technical Support!

See you on the bands!
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Neal - K3NC

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Posted 1 year ago

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Greg - N8GD

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Hiring you was one of the smartest moves FlexRadio has made (not that Tim and others aren't competent).  Your extended knowledge of Windows and how it interfaces with Flex programs has proved to be an invaluable resource for all of us.  Thanks for providing this info to those of us who feel comfortable working "under the hood" of Windows.  I know it will greatly reduce the support load on the Flex organization.
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Tim - W4TME, Customer Experience Manager

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Who do you think is teaching him? ;-)
Photo of Greg - N8GD

Greg - N8GD

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Yeah, Tim.  That's why I put the disclaimer in parentheses regarding competency.  I know you're happy to have Neal's help, especially when things like the Win 10 1803 debacle come along.  Don't worry, you'll always be the "Mayor" here on the Community!
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Tim - W4TME, Customer Experience Manager

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I am the Exalted Grand PoohBah!  No lowly "mayor" for me :-D 
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Gary L. Robinson

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Neil N4FN

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Good job... Exalted Grand PoohBah!  The only thing better is "Sublime Wizard" and that is reserved for Mack W4AX and Chuck AE4CW
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K1UO - Larry

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I would be happy to second that thought Greg.
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Matt NQ6N

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Does anyone know how these devices are being renamed or why Windows would decide to rename them to a different name than the one that was configured when they were installed?  Is there an identifier (other than the name) that remains correct/constant even when the update screws up the names? 
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Tim - W4TME, Customer Experience Manager

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What and why did Microsoft do what they did?  This is a question that is akin to knowing what is happening inside a black hole.  Seriously, they have code that is designed to "migrate" kernel mode drivers during an update.  These Win10 updates are in reality more like an operating system upgrade and if anyone has done Windows OS upgrades before, you know how brilliantly successful that went.

This is the new "normal" of having an operating system as a service; these updates will continue to mangle stuff and I'll be optimistic, eventually, fingers crossed, they will get better at it.  What we can do is what we have done and that is to mobilize our support resources, find workarounds and fix broken updates as fast as we can.  I know it isn't perfect, and it is frustrating for you as the user and several orders of magnitude more frustrating for FlexRadio Support and Engineering.
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Michael Walker, Official Rep

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Be aware that the Grand BooBah and his cronies haven't had much sleep in the last week.  And, no, I am not making this up. 

Imagine if this was mission critical applications, as that is the type of service they are providing.  As someone who has been in the Data Protection and Data Recovery business for decades, my hat is off to all of them.

Thanks guys!
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Bill W2PKY

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Does anyone know why an Uninstall and Reinstall does not correct the the names?
Sorry if I missed it.
I had several other issues with 1803; Printer driver and Meinberg needed to be reinstalled.
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Tim - W4TME, Customer Experience Manager

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Yes.  As part of the 1803 Update, Windows tries to "migrate" the DAX kernel-mode drivers and in doing so add a bunch of registry entries that were not added by the installer, so when the uninstaller runs, it does not remove entries that it does not know about.  It is the vestige of registry entries that have to be removed before the installer can re-install the DAX drivers correctly.
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Best explanation thanks Tim. It all makes sense now.

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Jerry - W2TXB

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Does the latest (i.e., yesterday's) update affect this problem in any way? I installed this update, and will, when time becomes available) check to see if anything (else) has changed with respect to SmartSDR, DAX, and VSP.

"May 8, 2018—KB4103721 (OS Build 17134.48) Applies to: Windows 10 version 1803

Improvements and fixes

This update includes quality improvements. No new operating system features are being introduced in this update. Key changes include:

  • Addresses an issue with the April 2018 Windows Servicing update that causes App-V Scripts (User Scripts) to stop working. 
  • Addresses an issue that may cause some devices to stop responding or working when using applications, such as Cortana or Chrome, after installing the Windows 10 April 2018 Update.

  • Addresses an issue that prevents certain VPN apps from working on builds of Windows 10, version 1803. These apps were developed using an SDK version that precedes Windows 10, version 1803, and use the public RasSetEntryProperties API.
  • Addresses additional issues with updated time zone information. 
  • Addresses an issue that may cause an error when connecting to a Remote Desktop server. For more information, see CredSSP updates for CVE-2018-0886.
  • Security updates to Windows Server, Microsoft Edge, Internet Explorer, Microsoft scripting engine, Windows app platform and frameworks, Windows kernel, Microsoft Graphics Component, Windows storage and filesystems, HTML help, and Windows Hyper-V.

If you installed earlier updates, only the new fixes in this package will be downloaded and installed on your device.

For more information about the resolved security vulnerabilities, see the Security Update Guide.

Known issues in this update

Microsoft is not currently aware of any issues with this update."
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Tim - W4TME, Customer Experience Manager

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I installed the patches yesterday and DAX and CAT are still working just fine on my test machine.  In general, these minor patches do not do the mayhem that an Update does.
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Rick Hadley - W0FG

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I installed this morning's update on both computers with no apparent corruption of the drivers, but I did have to do an additional reboot on both the computer and the radio to get DAX-IQ to recognize the panadaptors for CW Skimmer and DAX-AUDIO to WSJT-X.  Following the reboots all appears normal on both radios and computers.
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Joe - KC2TN

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Thanks to everyone for posting their experiences here. After experiencing my own set of problems, these posts helped me recover from a frustrating “NO TX AUDIO” problem when using WSJT-X. Everything else seemed to be OK exception that one driver. I wound up completely removing ALL versions of SSDR and WSJT-X and then “Unhiding” ALL hidden device drivers and then deleting ALL FLEX/DAX related drivers. After reinstalling SSDR and WSJT-X everything worked fine. Took about 30 minutes to fix. However, that was after days of on and off again troubleshooting trying to figure out why my TX audio wasn’t working even though ALL my settings looked OK. Great group here!
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OK, I have had some trouble with DAX channels not working right.  I followed the above suggestions and discovered under sound...recording....numerous copies of DAX channels.  How do I know which ones to delete they all look correct, its just their are multiple copies of of the DAX channels, especially 2,3,4 the ones I had problems with??????

Should I just open a support ticket??

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Jay / NO5J

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First take a look in Device Manager, and  not under Sound ... recording, etc, which serves a different function entirely, it's used to modify the properties of installed devices, not add or remove them.

For me the correct number of DAX devices is a total of 28. That's 8 DAX Audio RX devices, 8 DAX Reserved Audio RX devices, 4 DAX IQ RX devices, 4 DAX Reserved IQ RX devices, 1 DAX Audio TX device, 1 DAX Reserved Audio TX, 1 DAX Mic Audio device and 1 DAX Reserved Mic Audio device.

All of them are required, but depending on your radio model some may never be used. but SmartSDR expects all of them to be there.

If you're missing any of those, or have any that are duplicated, you will eventually have problems with DAX.

Also, occasionally Windows Updates, fail to update, occasionally SmartSDR DAX when installed has failed to cleanly remove all of them and after reinstalling SmartSDR, you may find broken, misnamed, or duplicated "Ghosted" DAX devices. 

So yes, you can end up with the wrong number of devices. 

If you see that trouble performing a Full Clean, Removal and Reinstall of SmartSDR, should result in the correct 28 devices. 

Doing so can return your PC back to the state it was in before the first installation of SmartSDR, allowing you to reinstall it correctly.

Just about anything else you try to do, is unlikely to improve the problem.

Windows call these DAX devices Audio Endpoints, think of them as the RCA connectors on the ends of an audio patch cable, a total of 14 virtual audio patch cables, the Reserved devices are the ends that are virtually connected at the radio end of the cable, the other end is the end that virtually connects to digital software, you will run on the PC. 

Removing any of the required Endpoint devices is like Virtually snipping off the RCA connectors from the virtual audio patch cables. They can't be repaired, only replacement will work. Think of any Ghosted endpoints as virtual RCA connectors with the virtual cable wire Damaged, Destroyed, or removed too. Just like any other damaged/destroyed connector you find in your Junk Box, they are Virtually useless. 

#FlexRadio IRC chat

   73, Jay - NO5J

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Michael Pfaeffle (K3FEF)

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WOW!  I was struggling with the old scripts for the driver errors - rebooting at each step - nothing.  Then I found this and.... BINGO!  It worked.  Thank you!
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David Martin

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Thanks Jay for your very informative text, especially the link that I haven’t seen before.

I have been unable to get all the Dax drivers successfully installed on Windows 10 - and neither can I get them uninstalled. The uninstallation stalls at:

Processing HWID FlexRadioSystems_DAX_IQ

That is as far as uninstallation progresses. I’m confident that if I can ever uninstall, I’ll be able to,install correctly! Any comments or suggestions would be appreciated.

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Jay / NO5J

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If you drop in to the IRC channel, maybe I can get you sorted out. the link to the webchat client is in my signature below.  Fill in your callsign as your nickname and hit enter.

    #FlexRadio IRC chat

For real-time discussions


User created documentation.

         73, Jay - NO5J

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Danny K5CG

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This site can’t be reached took too long to respond.

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Jay / NO5J

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OOPs, I had a power glitch yesterday.
SDRgadgets should be back online now.

    #FlexRadio IRC chat

For real-time discussions


User created documentation.

         73, Jay - NO5J

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Dave Gipson

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Jay is stellar and spent hours working with me on the issue a short time ago. I don't think I properly thanked him then so I will here.. Thank you Jay for sticking with me!!!
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Neal Pollack, N6YFM

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Tim mentioned that the reason an uninstall/reinstall cycle does not fix it is because MickySoft with their windows update migrated the entries to a new name and created registry entries that the Flex installer did not create.   Hence the Flex installer package did have that list of registry entries to uninstall.

As someone both cost conscience and also all about customer satisfaction, I still maintain the point
I made earlier;   If Flex wants to save money and reduce both user frustration and time spent on
support calls, they need to add an optional click-box on the installer package prompt screen that
lets the user select "Deep Clean, Re-Install", which will warn the user to backup profiles, then
proceed to scan the registry, purge ANY entry with Flex's keywords (This is what Norton
Uninstaller/cleaner does), and then after that proceed to reinstall.     With coding, it is very easy to
match/find the registry entries that MickySoft migrated with their update.   The risk is low in doing that.   The rewards are huge, both financially and customer frustration wise.

Work Smart, Not Hard.

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ON7NQ - Danny

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Still having an issue I can't seem to resolve..
On 1 PC all audio devices are ok but on the 2nd PC I still get an error.
At first look I don't have an "ghost" devices but when you look into detail it says :

Device SWD\MMDEVAPI\{}.{ad21fc8f-b2b5-45ef-bd3a-995c7fa845ee} was not migrated due to partial or ambiguous match.

Last Device Instance Id: SWD\MMDEVAPI\{}.{c62aa6db-c543-4e0d-a6a2-c6fbcdb31852}
Class Guid: {c166523c-fe0c-4a94-a586-f1a80cfbbf3e}
Location Path:
Migration Rank: 0xF00000000000F120
Present: false
Status: 0xC0000719

I'm guessing this could be a Realtek driver issue...I did an update of the drive prior to installing SmartSDR..Anyone have a clue ?Thanks..
73 - ON7NQ Danny

OK disregard ! Found the problem...ugh
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John - K3MA

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IF you are having trouble figuring out if a DAX device is the right name or not or what name to correct it too.  You can find out the correct name before Windows changed it by going to the Level tab and you will see the old correct name above the level bar.  Seems that Windows missed changing that also.
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What is a "Level tab"    where can I find it.  I wish I could save my device manager audio Flex settings (28 of them) to a file for the next time I have to do these tedious procedures.  Thanks for your input, Jim
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Chuck - KJ6HT

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Many thanks, your tip on finding the correct name on the level tab really helped.
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John - K3MA

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Thanks Chuck but really Neal deserves all the credit for this thread.  I agree with one other poster that Flex made a good decision bringing him on board.  I have worked with Neal over the past 4 years and alway found his advice to be spot on and at a level that a end user can understand.
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Thanks for your solution for DAX errors.    It was THE ONLY APPROACH THAT FIXED MY MESS.
I have been doing many many manual DAX uninstalls according to Tim's thread, and re-installs along with many many SDR removals/re-installs, again following exactly Tim's approach. That never fixed the DAX startup errors.  The name mangling was indeed my problem.  I couldn't read the blued entries (blured) above the change icon field, but  eventually figured it out with the help of Jay - NO5J's listing of the required 28 DAX audio settings. This all took me many hours but I'm happy its fixed.  I assume there are hundreds of other Flex SDR owners that struggle with this every time Windows updates.  I wish all these fine comments from 7 months ago could be condensed and published in a Flex help and support area instead of pouring over all these comments trying to figure out what works.

73, Jim -  
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Michael Coslo

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Once again the begging pleading, crying call for a Linux SSDR. That would take the world's best radio and make it darn near perfect as we would have reliable setups on our Linux and MacOS computers, and then not have to worry so much about what has become a permanent fixture of Flex Radios - the windows 10 post update failure.
Photo of Ted  VE3TRQ


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Don't kid yourself - Linux audio has its warts, too! I can't count the times I had to redo the audio configuration for wsjt-x or Fldigi after an update followed by a reboot.

I still prefer Linux and MacOS over Windows for many things, although when SSDR on Windows is working correctly, it works very well.
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Michael Coslo

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Having used computers since 70's IBM360's days, I agree, no OS is perfect. But  W10 is terribly brittle - or else I'm giving support to the really unlucky crowd! Most Linux support is Windows users trying to enforce Windows on Linux, and if I relied on MacOS, I'd be lonely.

I only bring up my wishes because I do know that W10 unreliability has cost sales.
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I use Mac OS when doing digital stuff. I find that dogparkSDR along with xDAX, xCAT and Loopback work great together. Mac OS is a more stable environment than Windows OS, that's my opinion.
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Michael Coslo

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Not an opinion, but a demonstrable fact. MacOS is demonstrably more stable.
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David G4NRT / Z21NRT

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I have had an interesting day.  I was getting short of disk space so decided to uninstall SmartSDR and all its previous versions and start over.  That may not have been wise! I followed the latest set of Tim's instructions to the letter and rebooted as required.  That was a challenge as so many setting seems to be persistent - even using Revo Uninstaller Pro left some things set.  

Once I had it all re-installed I checked my audio settings in DevMgr and found a number of spurious errors just like Neal suggested.  

I followed the above instructions EXACTLY but after my reboot I found that some of these additional ports (which I had uninstalled) had re-appeared: even though I had deleted them.

Things seem to be working OK with my 6700 but I would feel much happier having a really clean installation of SmartSDR / SmartSDR CAT and DAX.  

What can I do or am I forever to be stuck with these odd settings (DAX Audio RX 2 (FlexRadio Systems DAX IQ for example)?

Thanks in advance and 73,  David G4NRT
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Michael Coslo

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Hi David, If you are going to use SSDR, Windows 7 is a stable OS to use.  Another option is to use a W10 computer that does not access the internet. I do have an airgapped W10 network that runs pretty flawlessly.  I'd use the W7 if you have to use Windows.
Or, you can run W10 Enterprise, and lock that beast down big time. I am getting that option soon, as Microsoft has become the biggest impediment of proper computer operation.

To get it fixed on your computer now, Jay or a help ticket should get you running FB, but then you just wait for another update.
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David G4NRT / Z21NRT

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Thanks Michael.  Using Windows 7 is not an option.  This is my only PC.  Everything else in my system is on Macs.

I would like to just get my Windows 10 fixed.

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Charlie Wirth

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I am having issues with Dax on a Windows 10 computer as it relates to Ham Radio Deluxe. I was not getting any waterfall or audio input at all.  Put in a ticket to HRD support and they tried to help but then stopped responding to my requests. It seems that Tim's Dax uninstall/reinstall fix he posted works but only for a short time.  I created a batch file that will automate the uninstalling and reinstalling Dax on a Win 10 computer.  It seems to me with the fact that Windows 7 is reaching end of life on January 14, 2020 and there will be no more updates to it that there should be a push to get Dax working with Windows 10.
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Michael N3LI

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That's the reason that Windows 7 works so well, almost never updated any more.
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Thanks Neal, this fixed my problem!!!
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Also,,,THANKS,,,fixed my problem too. 73
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Max, N5NHJ

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It could happen that the name of the devices is messed up at the point that is not easy to recognize which device belongs to which category/controller.

The Flex devices can be part of one of these 4 categories:


Opening Device Manager, expanding Sound, video and game controllers shows those 4 controllers

The following procedure can help in matching Controllers and Devices:

Open the 'Properties' window for each controller, click on details and select 'Device instance path' from the drop down menu. Keep note of the path.

In my case (Win10/Dax 3.0.27) I have:

DAX IQ          ROOT\MEDIA\0004
DAX TX         ROOT\MEDIA\0007

Expand 'Audio inputs and outputs', double click on the device you want to verify/fix, click on 'Details' and select 'Parent' from the drop down menu. 'Value' shows the controller at which that device belongs.

Hope this will make the life easier...

73, Max