Conditions were OK with QSB on some stations. SSN = 72, SFI = 153, A = 33, K = 2.

Hi all,?

Next monday, March 31 is the next?QCX Challenge, on the regular bands.
Times are 1300Z, 1900Z and 0300Z (Tuesday).
Time to get on the air with your?QCX, QDX or QMX?rigs!?

Use any accepted mode where you can exchange a signal report, your name, rig and power. Note that from now on, this means that also SSB can be used by those that have a QMX/QMX+ with the new firmware :-)

See all info here :?https://www.qrp-labs.com/party.html
Enter your scores at?https://3830scores.com/

Join the discord page in the #qcx-qrp-operation channel to post your QRG or exchange other info, or just have a chat with other QRP Labs friends ...
?

Also check out the spotting website by Tom,DK3DUA :?

PS : note that from now on, the QCX WARC Party has moved to the?second monday?of the month, so the next one is on April 14.

73 es GL,
Luc ON7DQ

Mel,

I don't know, but I'm wondering if there is a relationship.

--

73, Dan - W2DLC

On Fri, Mar 28, 2025 at 02:26 AM, Ellis Simon GM4GZW wrote:

Can you give me a clue as to which direction you changed the band sweep values?

I think it will be different for each QMX.? It may be associated with LPF parasitic issues or whatever.? I have no real clue why/how these settings affect the calibration.?

?

But please everyone, read this:

After you successfully do the calibration,? please return the band edges to their original settings, or at least put the center frequency within the ham band allocation and the band edges equal to or greater than the ham band edges.? Otherwise you will later find that something is not working as expected.?

?

Stan KC7XE?

?

?

?

Hi Dan,

?

Should we be adjust band parameter just so that we can get a complete configuration run?

Because we cant get a complete configuration run, does that not signify that something is not quite right? i.e. LPF or BPF needs adjusting?

?

We're tweaking band configuration just so that we can get the 'right' result.. Are we going the right thing?

?

Mel. M0KMD.

I could only get calibration on 80m to get beyond ~20% by using all the configuration parameters from the 40m band configuration for the 80m band, both frequencies and LPF.? Still required a lot of tweeking!

I would expect they would look the same, I'm just wondering if the predistortion curve is related to the peak amplitudes permitted by the LPFs. Maybe moving the band edges and centers to center on the peak of the LPF curves is the reason for the changes in the predistortion curves.

--

73, Dan - W2DLC

I had a quick look at the 20M LPF curve and it looked the same. I didn't examine it carefully though.

?

Ellis

I'm wondering if there is a correlation between the band edges and centers settings improving the curves and the actual LPF peaks.?

--

73, Dan - W2DLC

I was afraid of that. While I do have an o-scope and could take readings, it would be an exercise in futility for me. Should the issue turn out to be one of those sub-microscopic components like the transistors on the underside of the board - I doubt I’d be able to replace it.?

So, please prepare a guest room for its visit. Will ship it out Saturday. ?

Jim / K7TXA
Eagle, ID

SKCC 10447T
BUG 301

What’s the version of your wsjt-x and is it on macOS? I noticed a weird bug that wsjt-x v2.7.0 on macOS can deafen qmx every time it transmits or changes the band. Entering the menu then exit restores the audio. This happens only if you select QCX/QDX or QMX for the radio type. Kenwood TS480 works fine.?

While seems likely you may get version 3, building from a screen works nicely. Just starting my qmx plus build now. Plenty of room on small surface for my screen, kit and tools. It's actually easier to reference assembly manual in vertical position. Try it before spilling the ink.?

?

Curt wb8yyy?

Hey Dudley,?

?

The capacitors are trained to hide in the knobs on these kits. Look in the cavity where the shaft goes. I have three of the QMX series kits and have experienced capacitors in the shaft cavity on all three.?

73

Dick

W4PID

We had nine folks join the MI QRP Zoom Chat on 27 March. Please join us Thursday April 03 (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. New hams are encouraged to participate and ask questions. 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:

The topic for Thursday, 03 April will be TBD.

Pete WK8S

Ed AB8DF

Ernie NE3TE

Stan WB8QJZ

Tom WW8LA

Casey KC9IH

Jacob N3JU

Stuart M0SGV

John K4XNY

Pete shared his recent experiences with a POTA PERformer vertical antenna. He went to a local park and took a bunch of pictures. He was doing WSPR testing and showed a report from WSPRNet. His results were good and he is convinced that the elevated radials greatly improve the vertical antenna performance. Ernie mentioned that Buddipole uses one elevated radial and recommends going to the Buddipole web site. K6ARK has videos on different ways to connect the radial wires. Steppir has information on elevated radials on their web site.

Michael KB9VBR WI POTA Videos and J-Pole Antenna Sales

KJ6ER - PERformer, Challenger and Dominatorportable? ? video

The agenda for the 03 April QRP Chat:

During the open forum anyone can take the floor. We will go one by one until all have had a chance to have the floor. Files, pictures and presentations can be shared if you have any. Please try to stay muted when someone has the floor.

Thanks

Ed

AB8DF

Hi Doug,

?

I agree with Nate that the symptom you describe is not normal.? My guess is that the BS170s are getting warm.? The resistance of a MOSFET increases as the temperature rises, reducing the power output.? The best way to verify this is to open the lid of the QDX and use canned air to cool the BS170s.? If the power increases, then heat is the cause.

?

73

Evan

AC9TU

Doug, that's not normal, no.? I'm not sure what to point to, though. Something impacted by current...... so could be T1, L14, or BS170 soldering faults? I suppose if something in the LPF was heating too, but I assume this is happening on 20 and 40m, so probably not that.??

?

-Nate

N8BTR?

Sorry all who answered. ?Guess I missed reading about the rail and tried to look for my message and erase but it wasn’t listed at the time. ?My 82 year old eyes finally saw the indentations on both sides and took pliers and snapped them off. ?Sorry for needless post.