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Hi Volkert,

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For Win7 you need to install the serial port driver from here:

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As you saw on your Win10 machine that the QMX was recognised and showing the available devices on your QMX.

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To show the QMX as a removable USB device, you must go into the update firmware menu option.

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I hope this helps.

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Regards,

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Mel. M0KMD.

Für Win7 muss noch ein Treiber installiert werden (siehe Wiki). Wenn das wegen der Sprache mühsam wird, schreibe bitte.

Hallo Volkert,

wenn der PC COM-Port und QMX Audio erkennt l?uft bereits die Firmware. In dem Fall zeigt der QMX kein USB-Laufwerk.

73 Ludwig

cq

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Nun habe ich den QMX schon einige Tage. Bisher ist es mir nicht gelungen, die Firmware zu laden.

Im Detail:

Der QMX soll auf einem Mini-PC ZOTAC für Portable Eins?tze installiert werden

System: Win7 32Bit.

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Der QRP-Labs QMX-Transceiver wird?im Ger?te-Manager mit Fehlercode 28 und als COM1.

erkannt, erscheint aber nicht als Wechseldatentr?ger im Explorer?

Code 28: Treiber fehlt!

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Nun habe ich die QMX Installation auf dem Desktop???? Win10/64 versucht.

Der QRP-Labs QMX wird?als ?Serielles USB-Ger?t“ mit COM3 ?und bei ?Audio“ als QMX-Transceiver im Ger?te-Manager?erkannt, erscheint aber nicht als Wechseldatentr?ger im Explorer?:

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Was kann ich tun, um die Firmware zu laden?

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Google ?bersetzung:

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cq

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I've had the QMX for a few days now. So far, I haven't been able to load the firmware.

In detail:

The QMX is to be installed on a ZOTAC mini-PC for portable use.

System: Win7 32-bit.

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The QRP-Labs QMX transceiver is recognized in the Device Manager with error code 28 and as COM1.

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but it doesn't appear as a removable drive in Explorer.

Code 28: Driver missing!

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Now I've tried installing the QMX on the Win10/64 desktop.

The QRP-Labs QMX is recognized as a "Serial USB Device" with COM3 and under "Audio" as a QMX transceiver in the Device Manager, but it doesn't appear as a removable drive in Explorer.

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What can I do to load the firmware?

I came across the same problems with USB/LSB and SWR jumping. But In my case SWR protection works. Which causes problems from time to time.

And as you can obviously see, I added a couple small heat sinks using a thin coat of contact cement to hopefully add a bit more metal mass. Just make sure they do not touch.

Tim - K5DEZ

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After assembling a QDX rig for a local ham I received a couple of the QDX PA mod PC boards made by WB2CBA which have the FDT86256 mosfets. They have a max voltage of 150V compared to the 60V of the BS170. Since I like to experiment I decided to try and adapt one of the boards to my QMX+. I filed off the two "tabs" opposite the mosfets being careful not to file off? any of the traces. It fit perfectly where the BS170's were. After some testing it seems to work well. My QMX+ is presently wired for 9V and I have a Buck-Boost converter stuck on the back set at 10V so I can use any battery I like from 5V-30V. On 80m-30m I can easily get 5w with the 10v input. Since I like to "play with fire" I plugged in my 12.6V battery and got 6.5w-8W on the lower bands. The mosfets stayed very cool....into a dummy load. While playing on FT8 with my Hexbeam and low SWR sometimes the finals got warm and actually got pretty hot on some of the higher bands but kept work fine.?

? ?If anyone else out there can or wants to give it a try, especially if you have the proper test equipment please let me/everyone know what you found.

The info for the PC boards are here... ?

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Tim - K5DEZ

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On Tue, Apr 8, 2025 at 08:38 PM, Steve Sutterer AK0M wrote:

On p25 in section 2.8 of the rev 3 assembly manual, it clearly states “Check that there is NO DC continuity from the points marked A, and ground.” ?This would be after T501 is installed.

True, you are correct.? Sorry, I didn't mean to completely discount that.? I thought you had missed the statement before that, just under the photo, it states "Now check for DC continuity with a DVM between all the points marked A in the photograph above." -- because this is the main soldering test for the primary windings, and the reason those particular A points were chosen.? The test between these A points and ground is a second test that verifies that the primary didn't get shorted to the secondary (which is connected to ground), or to some other grounding point.

Stan KC7XE

Looks much better now.? If you want to experiment with taking off another turn on L401a or L510, it won't hurt anything.

And leaving it set to share 15/17 rather than 20/17 will also work fine - the only side effect I know of is that you will need to remember to make this setting again whenever you do a factory reset.

Just also remember to evaluate the changes by listening to received signals - is it better, and good enough for your liking?

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I'm wondering a little what makes the 'top' of the 15m BPF only get up to about -12.? It would be better if that were higher.?? Maybe adjusting L510 would help with that, but I'm not sure what all causes it.? It is a little lower than on your first plot of that band, so something about removing turns may also have affected it.?? It may be interesting to see if bunching the turns together would make that go up by increasing the Q of the filter - if so, removing another turn and bunching them a bit may give better results.? But I am way out of my depth here -? I can only guess at cause/effect.? So hopefully someone else can comment.? Attenuation could be coming from the LPFs or from efficiency of this filter.

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One note to remember about the RF and LPF scans: the scale on the LPF scans is made by normalizing some set of the passband values to 0dB, and making everything relative from there on each scan; whereas the RF scans measure dB values offset from a common reference (the fixed level of the test signal clk2).? So when the top of the RF scan is down like that, it does indicate a lower signal level getting through.

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Stan KC7XE

Hi Stan,

On p25 in section 2.8 of the rev 3 assembly manual, it clearly states “Check that there is NO DC continuity from the points marked A, and ground.” ?This would be after T501 is installed.

Thanks for the explanation of the mosfet protection diodes.?
I will have this board and T501 in hand on Thursday and hopefully figure out why we are seeing continuity to ground after T501 is installed, even though the windings on the uninstalled T501 show no continuity.?
73,

Steve AK0M

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I am using a GPS QLG2 to supply 1 second pulses to a progrock, the progrock is generating 27Mhz for a AD4351 DDS and 24Mhz for a receive function. On both the signals generated there is a "blip" when the 1pps fires, I have removed the bright green external LED I am using to no avail, also there is no modulating pulse if the GPS is not locked. This may be an old problem, any help appreciated 73 Dave

Thanks Stan, this is great. The explanation makes perfect sense to me. I ended up removing three (!) turns from the 15m portion of 401a. I think I could possibly benefit from removing one more. Or possibly removing a turn from L510 since the windings are about as equally spaced out as I can make them. In any case, here are the new sweeps:

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17m still looks pretty bad, and 20m is getting close to the edge. I thought I would try reconfiguring 17m to use BPF 0 instead of 1 (so sharing with 15m instead of 20) and I get the following result:

This seems better than on BPF1, but I'm not sure if setting it up this way would have any unintended consequences. Any thoughts on whether I should try taking another turn off of 401a or call it close enough? Thanks again for your guidance -?

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Alex

Yes, I have run FT8 and JS8-Call successfully as well with those settings.

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The rise and fall settings had something to do with correcting the double flash low audio error code. I do not know what if any optimizations can be made to those values.

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FT8 and JS8 tone times are slow enough it should work fine with min samples at default. I had to decrease the value so the fastest VARA FSK mode would properly modulate.

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I do not know if there is another way to set parameters.

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I believe the settings are stored in non-volatile memory, so you only need to set them once. I have not had need to change the settings from the ones I found to work well for VARA so it's been set it and forget it with my QDX (I do need to adjust the per band audio levels a bit more but that's on receive)

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Cheers

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- Jadon

KJ7RBS

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I have been enjoying the 10-20m QMX for several weeks.? I used two 1N4001 diodes to drop the voltage to about 10.5V.? I had a beacon set on 10m.? Antenna SWR was 1.2.? Everything worked great until today.? The diodes melted and the QMX is dead.

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I took the unit out of the case but there was no visible damage.? HELP!

Stan, Ludwig, Dan, Jeff and all the others, whose names I cannot remember at this moment, for all your time and effort in volunteering to help others...