Re: QMX Block Diagram

I don't know about a block diagram, but I really liked the block by block discussion from Hans on this talk

?

#QMX chasing high noise level on 20m #qmx

I have a high band QMX, rev3.? I'm chasing a high background noise level on 20m.

?

Over the weekend I tried my QMX in the Flight of the Bumblebees, which provided a good test of the ability to pick out weak signals against background noise.? I observed that the background noise on 20m was quite high, to the point that I could only hear a couple of stations well enough to work them.? I have previously done two successful POTA activations on 20m with the same setup, and have heard strong hunter signals just fine.

?

After upgrading the firmware to v21 to correct a different problem, I ran diagnostics today on 20m, 17m, and 15m, my favorite bands.?

?

First of all, with a dummy load attached or unattached, I hear louder noise on 20m than I do on 17m or 15m.

?

Now, attaching the dummy load, here is what I observed in the diagnostics:

The RF sweeps and the LPF sweeps look fine, as compared with the operations manual.
The Audio sweeps look fine qualitatively.? LSB levels are OK, –60dB ("in the noise").? But, the USB levels are –16dB, –5dB, and –12dB on 20m, 17m, and 15m, respectively, considerably lower on 20m and 15m than what I see in the operations manual.
The Image sweeps show a –60dB LSB level (again, in the noise).? The USB peaks, however, are lower than I see in the operations manual: –17dB, –5dB , and –13dB on 20m, 17m, and 15m, respectively, consistent what what was observed in the audio sweeps.
Finally, the ADC I/Q tests showed very noisy sinusoids on 20m, clean sinusoids on 17m, and noiser sinusoids on 15m.? The sinusoid amplitudes were ±18244, ±54184, and ±29281 on 20m, 17m, and 15m, respectively.

There is a pattern of weak signal levels on 20m.? Seeking advice on where to go from here.

?

Thanks,

Eric

?

QMX limited output power for transverter?

#126889

Hello,

?

two questions:

1. is power limit regulation for CW and digi foreseen in future releases of firmware? I have a transverter which, unfortunately, can accept maximum input power of 100 mW. I cannot imagine I could handle this reasonably from 5W output but with 1 watt seems to be easier to achieve 13-16 dB attenuation without excessive heat dissipation.

2. When talking about such regulation, could 50 or 100 mW (CW or digi) be achievable by firmware??

?

73! Jindra

QMX Block Diagram

#126888

Is there a block diagram of the QMX? I am doing some troubleshooting and find that I get a bit lost in the detail of the schematic.

?

Thanks,

?

George, N9DXP

Michigan QRP Club Zoom Chat Report 7/25/24

#126887

开云体育

We had twelve folks show up for the 25 July Michigan QRP Zoom chat. The topic was Favorite QRP Rigs.

Pete WK8S

Ed AB8DF

Ernie W3ETE

Yvon AE7YD

Rick K8BMA

Muhsin TA1MHS

Glen WB4KTF

Dave N8SBE

Dan NM3A

Harry K9DXA

William KR8L

Casey KC9IH

Initial discussions were on powering the QRP Labs QMX+ and not being very tolerant with input power. There were several new folks that showed up so we had a round of introductions.

Rick started off by showing his SW-3B. We discussed encoder issues that QRP rigs can have. Rick described his POTA hunter set up.

Dan loves his QCX and has a TR-35 but the QMX is his favorite and uses a 84 ft long wire 3 AH biennia battery. Dan has a ZM-2 tuner ,T1 Elecraft tuner, LDG tuners and uses the SWR test feature in QMX to tune.

Dave showed QRP Guys tuning indicator that helps prevent high SWR while tuning. Dave’s first rig was a FT-817 but now uses a KX-2 because it is small, fits into packs and covers all the bands. His KX-2 has an internal battery, side rails and knob covers.

William uses a FT-817 running digital to chase DX. His best DX was VK. He also loves CW and POTA using a AX-1 antenna.

Muhsin has a collection of QRP Labs rigs. He uses a battery brick and FT-818, AT-10 ATU and a whip tuner. He also has a WB2CBA turner. He strongly recommends the Hermes Lite 2.

Glenn’s favorite rig is a TX-599x with a K5CBQ watt meter and dummy load. K5BCQ has a good collection of kits for QRP.

Casey has a collection of Ten Tec Century 21 transceivers and a Ramsey 40 tranceiver.

Pete loves his Wolf transceiver with LDG auto tuner in the shack. He uses his TR-45 lite for potable. You can get the Wolf transceiver from E Bay. It is a Russian design but now it is manufactured in China. The Russian hams still support it.

Yvon had some pics that he e-mailed of his rigs.

Next weeks topic is Favorite Antennas.

Please join us Thursday (and every Thursday) at 4PM Eastern for the Michigan QRP Club weekly QRP Chat where the main topics will be QRP and other ham interests. It's fun, it's easy, and it's free. You only need a computer, a smart phone, or a tablet that can connect to the Internet. OR if you can't be close to any of those you can join by audio with any standard phone. Just follow the directions below. No software needs be loaded or installed. Anyone can join and non members are welcome. Details are here:

Ed

AB8DF

Re: QDX High Band Rev 5 low power on 15M only

#126886

Nate this was a great diagnostic tip!

It was definitely the LPF.? I desoldered them, rewound and reinstalled - but now get nothing on 15/17. The troubleshooting continues...

Show quoted text

On Mon, Jul 29, 2024 at 12:55?PM natereik via <natereik=[email protected]> wrote:

On Mon, Jul 29, 2024 at 11:40 AM, Joel Sandin wrote:

I'm still perplexed why the 20M filter looks totally different in the serial console - instead of a 'hump' there is a dip that minimizes at around 14mhz. Is that expected? Maybe a separate issue?

Likely due to an effect of the receive BPF. In the QDX HB, 20 and 17 share a BPF slot, and some have found receive is down on 20m. The filter test reflects that. On Tx, only the LPF is inline, and thus you get full power output on 20m.?

?

As far as your 15m problem....you could try (into a dummy load) changing the LPF selection for 15m so it uses the 10/12m LPF, and see if your power goes up. That would confirm that the issue is in the LPF.

?

-Nate

N8BTR

Re: N1MM Logger+'s built-in spectrum display works with QMX I/Q output now

#126885

The v1 with original firmware had a 12KHz offset in IQ mode, unlikely but maybe the problem?

Hi Alan, thanks for pointing this out! Somehow I always thought QDX had the same 12kHz offset just like QMX, so when queried by N1MM, the DLL returned its LO frequency with an offset of -12k. Now I see "12kHz IF offset is removed when you enable IQ Mode." in the release notes of firmware v1_04. I've updated the DLL for QDX to return its LO frequency with zero-offset.

?

73 Zhenxing N6HAN

Re: QMX + dead

#126884

Hi Martin,

?

I'm in Hummelsbüttel.

No callsign yet, I'm still in SWL mode. Just passed the class A exam last week and I'm now waiting for the Bundesnetzagentur to assign the callsign.

Re: QMX: cheap GPS module confirmed compatible

#126883

Yes. The module has GND, VCC, RX and TX exposed on a pin header. RX is not used in this application. TX is connected to either ring or sleeve (not sure at the moment, consult with QMX docs), GND is shared between USB and TRS sleeve. PPS is tapped from the board as described and connected to either ring or sleeve – see the extra pin I added (with yellow wire). If you have doubts, you can always refer to the module pinout.

On 30 Jul 2024 at 03:14:14, cchalfant via <cchalfant=[email protected]> wrote:

Show quoted text

super helpful, thank you!

Did you connect the USB power ground and the ground (sleeve) on the 3.5mm TRS plug together?

Re: QMX as an ARDF-receiver?

#126882

On 30/07/2024 06:17, hamradio@... via groups.io wrote:
can the QMX be used as an ARDF-receiver?Torsten,

As it is the antenna that does the sensing all that is required is to match an antenna system to a suitable receiver.
The QDX/QMX Labs receivers are suitable.

73 Alan G4ZFQ

Re: Commercially available electret mic with PTT for QMX/QMX+

#126881

I plan to use a - active speaker/mic. They need rewiring for the QMX / truSDX (yes, same pinout)...but they do seem to on a very good deal at the moment!

QMX as an ARDF-receiver?

#126880

Good morning list :)

yesterday evening one question came up when talking about ARDF:
can the QMX be used as an ARDF-receiver?

Cheers,
Torsten

-- 
vy 73 de Torsten | DB2TE

/"\  ASCII Ribbon Campaign
\ /  Against HTML Mail
?X   www.asciiribbon.org
/ \

Re: When will we have variable bandwidth in cw mode?

#126879

Thank you. I spent a few hours tonight going back and forth from Digi to CW. It was very noisy on 20,?

and there was some fading too. The cw filter is one world and the Digi world another. The CW filter did very well. If you stay in that world, where you can decode and transmit, you soon feel more comfortable than hopping back and forth. So perhaps keeping things as they are is the correct solution!?

?

Re: #qmx #qmx+ Firmware 1_00_021: Bug fixes and enhancements #qmx

#126878

I can see I just missed it yesterday...

Re: When will we have variable bandwidth in cw mode?

#126877

Hello George

?

When variable bandwidth arrives, what is the possible narrowest filter,

before you have to change hardware and modify the board?

The filters are software defined in the firmware, not hardware defined. So I suppose the CPU capacity?becomes the question, and not one I know the answer to.?

?

That would certainly affect a decision. Also would 50 Hz be compatible with the decoder?

Yes, the decoder wouldn't mind...?

?

SSB is more important, since this is in the audio chain and those who want narrow can do it with?

very nice audio filters like WolfWave. So i suggest, if you can do a wide open setting in CW so you

can transmit and use your own filter, that might be an easy fix.?

WolfWave costs almost twice as much as QMX and is another plug-in piece of equipment... when the accessory costs more than the radio does, I start to think it could be violating the definition of "accessory". So the goal should be to have these things inside QMX if possible, when it's a matter of variable filtering which really as an SDR, QMX is perfectly designed and ready for!?

73 Hans G0UPL

Re: Part number QMX+

#126876

You can get them in packs of 10 or 20 from Aliexpress.?

Show quoted text

On Tue, 30 Jul 2024, 04:59 Bill Robbins via , <wa8cdu=[email protected]> wrote:

Does anyone have the Digikey or Mouser part number for the 6x6x12 tactile switch for the QMX+?? Thanks in advance.

?

Bill

Re: Commercially available electret mic with PTT for QMX/QMX+

#126875

Should be the same as trusdx, I have a k6ark mic I am planning to use with mine.

Commercially available electret mic with PTT for QMX/QMX+

#126874

Does anyone know of a commercially available mic with PTT button that is wired correctly for the 3.5mm mic input on the QMX/QMX+? ?

Looking at the QMX assembly manual, I’m thinking the pinout might be the same as another small QRP radio that uses an electret mic. ??

By commercially available, I just mean for purchase assembled rather than a kit. ?I’ve seen a few kits and the form factor doesn’t have a typical radio mic look.

Asking in advance of the SSB firmware down the road.

Re: 50 Watt Amplifier Repair Advice Request

#126873

In going through NA5Y's QRP-Labs 50 watt amplifier trouble shouting guide and doing all the voltage measurements both on receive and transmit

I found a discrepancy at the very last test point on the video.??At the test point located at the intersection of R8, L5, and the two 1N4007? diodes the voltage is supposed to be about .07 V on receive and about 70 volt on transmit.? But at that point on mine it is .1 V on receive and only 36 volt on transmit.

In other words it is almost exactly half what it should be on transmit.? This test point is right after the voltage doubler portion of the circuit which suggests that for some reason the voltage isn't being doubled.? That suggests to me the remaining trouble may be among the components that make up the voltage doubler?

(the four 1N4148 diodes and two 47uF capacitors). Alternatively I suppose the voltage doubler could be working but the signal presented upstream was half what it should be before passing to the voltage doubler. (I don't have an oscilloscope to check the RF input to that location.)

Prior to doing these tests I had replaced the two IRF510 final MOSFETs Q1 and Q2 as well as the two BS170 transistors .

With 13.4 Volt supply voltage and the R5 variable resistor set fully counter clockwise watt meter shows 8 watts of output power.

And still have the strange behaviour THE RED TRANSMIT LIGHTS STAYS ILLUMINATED FOR ABOUT A FULL SECOND AFTER A KEY PRESS and release.

This red LED dims slowly after key press release instead of being nearly instant off.? Help me understand this? Where is the power coming from to allow this slow LED extinguishment?? ?And which component to replace next? Thanks again in advance for any advice.

Re: FT8 setting issue

#126872

I have always had the same issue with my QMX. ?I’m happens on “Fake It” and “Rig”. ?So just stopped using split and everything seems to work OK. ?But it would be nice to have it working properly.

?

73, Bill NZ0T