Roger,
?
I just checked and the SWR protection never faulted into a dummy load. Full 4.9 watts on all bands.
?
Dean
|
Stan,
?
If I understand you correct, QMX + RIT and N1MM won't be a happy marriage by design.
The RIT switch off issue in RUN mode is kind of weird.
?
Anyway, it is a great contest radio. Enjoying it at the moment in the WPX contest where propagation could have been better.
?
73,
Roelof, pa0rdty
?
?
|
Does this happen into a dummy load?
73 Roger 8P6RX?
Get
This seems to be a complex problem because I do not understand what is happening. I will try to explain as best as I can.
?
QMX mid bands built for 12 volts and Z-11 Pro auto tuner.
?
I start on 40 meters and go to hardware then SWR tune and start the tune. The tuner light move and ends when a <1.5 SWR is reached. I then go to iambic and send CW at about 20 wpm. After about 10 dits the tuner jumps up to over 4 and the S protection letter shows on the screen after the last number. I cycle the menu, go to hardware, SWR tune and it shows <1.5 SWR. I go back to normal CW and the same pattern shows up again.
?
It happens on multiple bands and is frustrating because I can't complete a POTA contact let alone a ragchew.
?
My sBITx is also low power 1 - 4? watts and does not do this action with the tuner.
?
Any ideas where to look?
?
73, Dean/ N2TNN
|
This seems to be a complex problem because I do not understand what is happening. I will try to explain as best as I can.
?
QMX mid bands built for 12 volts and Z-11 Pro auto tuner.
?
I start on 40 meters and go to hardware then SWR tune and start the tune. The tuner light move and ends when a <1.5 SWR is reached. I then go to iambic and send CW at about 20 wpm. After about 10 dits the tuner jumps up to over 4 and the S protection letter shows on the screen after the last number. I cycle the menu, go to hardware, SWR tune and it shows <1.5 SWR. I go back to normal CW and the same pattern shows up again.
?
It happens on multiple bands and is frustrating because I can't complete a POTA contact let alone a ragchew.
?
My sBITx is also low power 1 - 4? watts and does not do this action with the tuner.
?
Any ideas where to look?
?
73, Dean/ N2TNN
|
Re: QMX+ firmware feature request
Would having the SWR sweep on the QMX display satisfy your need?
I asked Hans for this a while back but I'm not sure if he read my request (busy guy).
It seems that SWR sweep is the only terminal mode feature that is not available on the QMX display.
?
Hopefully, one of these ideas makes it onto his TBD list.
?
73, Mike KK7ER
?
|
Re: R520 Wrong component value.
I may have the same issue with my QMX+. It enters Safe Mode as soon as the key is pressed on 80m and 60m. The 40m and 30m bands work fine, although 40m and 20m have nearly zero power output, which I still need to troubleshoot. If SWR protection is disabled, the QMX+ will transmit on 80m, 40m, and 20m, but power output remains negligible on these bands. However, 30m and 60m output 5W. These test were performed transmitting into a Bird dummy load
?
When using the diagnostic SWR check I get 80m SWR 10, 60m SWR 10, 40m SWR 10, 30m SWR 10, 20m SWR 3.3. Not sure what 10 means, is this 1:1 or 10:1 SWR?
?
?
?
Dave
|
Hi Ari, currently you can leave CW wide open with a bandwidth of about 2700, or select any of several filters of 500Hz and narrower to 50Hz.? Nothing between 500Hz and wide open - that would indeed require a firmware mod, unless you use an external filter.
Stan KC7XE?
|
Ah, so it does!? I was coming from the perspective of adding the AGC to a rev 1 QCX+ and having all the extra wires.
?
Yours is so neatly constructed that I missed it!
?
73, Mike KK7ER
?
|
Re: 50 Watt Power Amplifier - Low Power, High Harmonics
#50w
#50wpa
The 'scope traces from your archive of the K0IKR post do resemble the issue I am having - if anything, my gate signals look a little more balanced than what he had happening.
?
I didn't keep a note of it but I believe I tried running up the bias to see if that improved power output - something to try today, checkingthe waveform at T3 to see if it gets better.
?
I have one of those "component guesser" testers that identify a lot of things and give a little graphic of the device symbol with some measurements made at unknown test conditions. I've only ever used this as a "go -no go" function tester - I wonder if the? parameters it measures would be an adequate representation of the device's performance in the amplifier? If they match on the tester, will they be good enough for the amplifier?? Alternatively, I can do a breadboard experiment and measure the threshold voltage the hard way - lots of multimeters!
?
The other idea that came to me at 3 AM today was if my winding of the binocular core was careless, perhaps too much leakage inductance?? However, looking at my T3 and the illustration in the instruction manual shows a similar amount of windings visible at the end - it's not like I've got a 5 mm gap between the end turn and the core.
?
So, my next steps are:
- Observe T3 waveform at 100 mA bias
- Order a half-dozen IRF510s from DigiKey - and hope they don't get lost in our impending postal strike.
- Sort through the new IRF510s and pick a pair with the closest match, try them out.
?
I was relieved to find I could remove and reinstall the board without losing the silicone pads - I had feared this was a one-way-only assembly.
?
Thanks for your tips and the archived photos!
?
Bill
|
Re: Release of version 2.0 of ABS solution for QMX+ (Automatic internal antenna tuner, internal battery and internal speaker with audio amp)
#PSU
#QMXplus
#audio
#ABS
#ATU
Please include me for a US based group buy.
?
-Dj, N1JOV
|
Re: SSB Cal problems with QMX (not +)
Thanks for your help, Stan. I'll follow up when I can go through your suggestions with my QMX. I have not yet put it on the air with an antenna.
73, Randy, KS4L?
|
Hi,
my QCX has been modified for a passband of around 900Hz and has found more use after the modification.
I have a half-built QMX+ and the specs say that cw filter is adjustable from 50-500Hz.
?
Many seasoned cw operators prefer much wider bandwidths for general cw working.?
I usually listen with around 1,2kHz BW, in tougher conditions the narrower BWs are a blessing.
?
As my QMX+ still awaits to get on the air I want to ask if it?s possible to make the bandwith wider tha 500Hz in CW mode?
If that is not the case, I would like to add this to the list of changes in the software of the QMX.
?
72 Ari OH9VL G-QRP 2068
|
Re: R520 Wrong component value.
All
Thanks for all your
comments.
It took me a while
to find this one. I kept pulling and re-winding T507. I was convinced
the problem must have been something I had done. I just did not
expect the problem to be one of the factory fitted SMD components.
At one point I also
pulled and re-wound T501 thinking that may have been at fault,
changing it from the 9V version to 12V.
All that did was
blow the BS170s when I ran the SSB calibration process, so I need to
change those as well.
Stephen
Good catch, Stephen. I had one QMX with cracked and missing bypass caps, but this was seen before I started assembly and didn't require any diagnostic acumen.
The two QMX kits I received last week looked quite pristine, and R520 and 522 checked out at 49.9 and 50.0 respectively.
72 de va3rr
|
Re: 50 Watt Power Amplifier - Low Power, High Harmonics
#50w
#50wpa
Bill,
?
If my memory serves, I found that increasing the bias of the IRF510s to 100mA over the starting current resulted in higher output power.? This makes the amp less efficient, but Class AB linear operation is 100mA per MOSFET for IRF510s, so there should be little danger to them.? I think differences in MOSFETs could cause these turn-on voltages.? Pushing the bias higher puts the one-giving issue in the more linear region.
?
The alternative is to replace both transistors with matched Vgs turn-on voltages as measured by a transistor tester.
?
It is worth a try.
?
73
Evan
AC9TU
|
Re: Release of version 2.0 of ABS solution for QMX+ (Automatic internal antenna tuner, internal battery and internal speaker with audio amp)
#PSU
#QMXplus
#audio
#ABS
#ATU
In for a US based group buy
|
Calibrate the QMX's time through Android APP(FT8TW)
I wanted to try using WSPR, but every time I reboot, I have to set the time on the QMX again. A friend told me there's a GPS module that can help calibrate the QMX's time. I thought to myself¡ªmy phone already has GPS, so why buy an extra GPS module just to set the time on the QMX? So, I added a feature to calibrate the QMX's time through FT8TW.
?
https://youtu.be/l8dey0vc6_E
|
Re: R520 Wrong component value.
Good catch, Stephen. I had one QMX with cracked and missing bypass caps, but this was seen before I started assembly and didn't require any diagnostic acumen.
The two QMX kits I received last week looked quite pristine, and R520 and 522 checked out at 49.9 and 50.0 respectively.
72 de va3rr
|
Re: R520 Wrong component value.
Yes as a matter of fact. I couldn't find the problem with my QMX Mid-band, so I sent it to Jeff, the renowned QRP Labs Repairman here in the states. Along with a cracked capacitor, he reported R520 being the wrong value also. I too, rewound T507 several times. Maybe it should be put on the check list of things to check before building. It's on it's way back to me and I can't wait to try it out.
?
73
James
|
Re: I made a protective cover for the QMX+ which also doubles as a stand and storage!
Ooooh so cool! ?When will Hobby Lobby have them in stock??
toggle quoted message
Show quoted text
On May 21, 2025, at 12:18?PM, James Silvester via groups.io <jamessiilvester@...> wrote:
? A variation in the same theme:-
|
Re: FDIM 2025 - Bringing SSB to the QMX (Hans's presentation)
Hi Dave
Polar Modulation generated SSB is mathematically the same in the end as SSB generated by traditional filter methods or traditional SDR modulator methods. It sounds the same. The point isn't that polar modulation generated SSB sounds different, it doesn't. The advantages of polar modulation are that the efficiency is high, therefore smaller heatsinks are required and the lower power consumption (for a given RF power output) also presents potential operational advantages. Lower cost is also a result. For example Flex use the same heatsink in the new 500W Aurora, as in their current 100W transceivers. Abandoning the requirement for linear power amplifiers also means lower cost parts can be used and higher performance (lower intermodulation products) is easier to obtain.
Controlled Envelope SSB (CESSB) is a different topic. The amplitude envelope of speech is spikey. Unfortunately when speech is modulated to SSB, then it is mathematically inevitable that it gets even more spikey. The average power of the transmission is much less than the Peak Envelope Power (PEP). If you have a 100W transmitter the average power of SSB may only be around 15W. CESSB is a way to remove the additional spikeyness inflicted by the SSB modulation, without causing distortion or any other disadvantage. This increases the average power of the transmission by typically 4-5dB. Which gives it another S-point or so. A 100W CESSB transmitter typically has the average power equivalent to a ~250W SSB transmitter. CESSB again won't sound different other than it will be around 1 S-point louder, which could make all the difference in DX conditions etc.?
Parametric equalization is used to adjust the relative bass and treble content of the audio. That could be used to correct microphone response. More typically it is recommended to boost treble content and reduce bass content of speech, because the bass tones apparently contribute little to intelligibility. Of course this adjustment makes the speech sound less natural. So it's a tradeoff.?
Compression boosts the quieter parts of speech relative to the loud spikes. Which also increases the average-to-peak power ratio so gives more capability to break through in DX conditions etc. But causes distortion. So again a tradeoff.?
73 Hans G0UPL
On Sat, May 24, 2025, 12:29 David Wilcox K8WPE via <Djwilcox01= [email protected]> wrote: I have held this question in until now. I don¡¯t even know the correct way to ask Google, but with all these different ¡°improved¡± methods of generating SSB can the average ham (let alone the 80 year old like me) tell the difference when listening on the air?? Does it make a difference? Does the envelope hold open longer to increase power out or something like that. From what Hans has explained I get the feeling that some of the newer methods do increase the power out.
Thanks for any explanation or reference to a easily understood answer. On May 24, 2025, at 12:50?AM, Shirley Dulcey KE1L <mark@...> wrote:
? Did anyone out there notice that FlexRadio is now copying QRP Labs? Not really, but their latest product (the Aurora series, announced right around Hamvention and scheduled to ship in 4Q25) is using EER?(aka polar modulation) generation of SSB. They worked with K1KP, the developer of the Polar Explorer that was demonstrated in 2019, to integrate the technology into a transceiver.
Of course, Guido PE1NNZ and his uSDX beat both products to market. Hans explains it so well, I almost understand it.?
|
W6MQI
Dj Merrill
Randy
va3rr
James
David Wilcox K8WPE