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QMX work with PA
Hello Hans!
My QMX works great with 1_01_003 firmware. I've calibrated it and SSB reports are very good. Thanks!?
Few problems:
1. Wattmeter indicator looks like very slowly responding to actual power in antenna. As if it is averaging for couple of seconds...
2. When I use my usual PA with 1.3 input SWR (measured with NanoVNA) QMX tends to stop transmitting in several seconds due to SWR Protection. And SWR meter displays some big figures which do not exist in reality (checked with my standard SDR transiver and NanoVNA).
3. Nothing changes on PTT output during TX. 5V stays on the ring and 0V on the tip.? |
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I'm still getting a weird phase error plot on 80m. It stops at 36%.? U shaped with near right angles at the corners. I tried adjusting the band config parameters, moving the centre Freq around. Still weird.? What band config settings are people using that gets a normal / full plot?
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73
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Simon?
VK3ELH?
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On Sat, Mar 22, 2025 at 11:37 PM, <adam@...> wrote:
Adam,? I had a similar wierd short plot on 20m (see earlier post on earlier beta thread with audio clips) which resulted in distorted transmit audio on 20m only (the other bands were good).? I found that going into the band configuration and changing the 20m centre frequency small amounts drastically changed the plot.? I settled on a 20m centre frequency of 14300000 which produced a smooth descending plot although not with as many points as say, 17m. ?
Cheers,
Glenn VK3YY. |
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On Mon, Mar 24, 2025 at 06:31 PM, Stan Dye wrote:
What is the factory default?? I must have fat fingered something. |
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Re: more WSJT-X touble
reading this I am not near my shack so I can not look up the HAMLIB version but I did update WSJT-X and then went back to the previous Hamlib Version. and I used a different USB port. That changed the com port. Strangely the QMX in and output changed from QMX...2 to QMX...3. Once I had discovered that the QMX+ worked with the rig set to TS 480. Sometimes it is a little game what to start first but it works in the end. So I will not touch it and not venture into the improved version. Digital will not be my main focus so if it works, I am fine with the basics.? Now I will wait for the feedback from all the SSB testers before installing that.
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Martin
DK3UW |
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Re: custom QCX-mini SOTA kit (found video)
On Mon, Mar 24, 2025 at 05:40 PM, VA3CJO - Chris "CJ" wrote:
Looks like a custom bracket to hold the components togetherI think that's just a cellphone mount for a camera tripod, along with a small tripod accessory bracket.? I have one that fits my QMX nicely.? |
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Re: Interesting thing happened on my 20-10 meter QMX after loading the latest FW 1.01.003
On Mon, Mar 24, 2025 at 12:43 PM, <adam@...> wrote:
?I never use 11m and wonder if I can just fill that slot with the 40m config??You don't need yo use that slot, but you can if you want.? There are several additional empty slots, just scroll further over. ?
But you will have to change one of the existing LPF filters to work on 40, and give proper harmonic rejection, while not compromising the desired bands.? This may not be easy, since most of the filters are shared between two bands.? There are only 3 LPF filter selection choices in the hardware.? I'm not sure if these can be spread across that wide of a bandwidth and still give good harmonic rejection.? 11m kind-of comes for free shared with a 10m or 12m LPF, so disabling or deleting it doesn't open a space for a distant other band.
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But I have never worked through the details-maybe there is a combination of sharing that will work.
Stan |
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Re: QMX+ Rev.3
Hi George I tested it extensively. The outputs (power in watts) is the same for the shiny black toroids.? 73 Hans G0UPL On Tue, Mar 25, 2025 at 6:48?AM George Korper via <georgekorper=[email protected]> wrote:
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Re: SSB Calibration blown finals
Tony's,
?
The fix Hans put into the SSB firmware to avoid blown finals?
is to periodically give it a rest so the finals can cool down.
If that does help (and my impression from forum reports is that it probably does),
then current can also be a problem.
?
Fortunately, the TN0110's can deal with both more voltage and more current than the BS170's.
So if they can transmit clean SSB on the QMX, that's a big win either way.
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Jerry, KE7ER
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On Mon, Mar 24, 2025 at 07:15 PM, Tony Scaminaci wrote:
Over the past year or so, it seems we came to an unofficial conclusion that BS170s were blowing due to high drain voltage as a result of high SWR or exceeding 12VDC at the supply input rather than overheating due to high current. TN0110 has a significantly higher drain voltage advantage over BS170 (100V vs 60V) and if it works well with SSB, I’ll be very happy. Keep us posted on your SSB adventure with TN0110. |
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Evan,
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Had always assumed that topology of those filters would present a high impedance to all harmonics.
I've attached an LTSpice simulation for the output LPF's on 80m
as used on the QCX, QCX_50W_Amp, the QMX, and the uBitx.
Does an AC Analysis on all of them from 1mhz to 20mhz.
Will archive those two (very small) files under KE7ER in the files section.
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You can click on the output node to see the voltage across the 50 ohm resistor,?
or click on the voltage source to see the current going into the LPF, which is inversely proportional to impedance.
Things look considerably more complicated than I was expecting.
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Looks like somewhere around the second harmonic, it's fairly high impedance looking into the LPF.
For the higher harmonics, that impedance is generally no more than the it is for the fundamental.
A push-pull amp should mostly take care of the second harmonic, and giving the odd harmonics an easy path to ground
suggests to me that these are most suited for a current mode amp.
So perhaps the QMX would do better with two L502's, so the two phases of BS170's can have their drains uncoupled.
This is what the uBitx final does.
The QCX 50W amp uses two windings on T2 to supply power to the FET's, that's equivalent to feeding power at
the center tap of the output transformer primary, and best suited for a voltage mode amp.
?
I have only recently found that these amps can be classified as voltage mode or current mode,
and so may be a bit to fixated on it.? ?It seems the distinction is not always as clear cut as I had expected.
All of these amps seem to work well enough, though I still wonder if the QMX could be more robust.
Could be that the best path is to just replace the BS170's with TN0110's when they blow..
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Jerry, KE7ER
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On Mon, Mar 24, 2025 at 02:36 PM, Evan Hand wrote:
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Re: SSB Calibration blown finals
开云体育
Thanks. The jury is still out for me since I have not managed to get good results with SSB yet. The microphone I tried worked but the audio was noisy and sounded distorted. I decided to order the electret that Hans is using to put one more stake in the ground
before experimenting further. I think it may just be a matter of getting all the settings right. If I start with his mic, I stand a better chance at getting there.
Tony
AD0VC
From: [email protected] <[email protected]> on behalf of Tony Scaminaci via groups.io <tonyscam@...>
Sent: Monday, March 24, 2025 8:15 PM To: [email protected] <[email protected]> Subject: Re: [QRPLabs] SSB Calibration blown finals ?
Hi Tony,
It’s good to hear that the calibration using TN0110 was similar to that of the BS170. I was initially concerned about SSB performance but when Hans mentioned his calibration technique, I had one of those Ah-Ha moments with hopes for a good outcome.
Thanks for running the calibration on both devices.
Over the past year or so, it seems we came to an unofficial conclusion that BS170s were blowing due to high drain voltage as a result of high SWR or exceeding 12VDC at the supply input rather than overheating due to high current. TN0110 has
a significantly higher drain voltage advantage over BS170 (100V vs 60V) and if it works well with SSB, I’ll be very happy. Keep us posted on your SSB adventure with TN0110.
Tony - AC9QY
On Sun, Mar 23, 2025 at 11:15?PM mux_folder2001 via
<canthony15=[email protected]> wrote:
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Re: SSB Calibration blown finals
Hi Tony, It’s good to hear that the calibration using TN0110 was similar to that of the BS170. I was initially concerned about SSB performance but when Hans mentioned his calibration technique, I had one of those Ah-Ha moments with hopes for a good outcome. Thanks for running the calibration on both devices. Over the past year or so, it seems we came to an unofficial conclusion that BS170s were blowing due to high drain voltage as a result of high SWR or exceeding 12VDC at the supply input rather than overheating due to high current. TN0110 has a significantly higher drain voltage advantage over BS170 (100V vs 60V) and if it works well with SSB, I’ll be very happy. Keep us posted on your SSB adventure with TN0110. Tony - AC9QY On Sun, Mar 23, 2025 at 11:15?PM mux_folder2001 via <canthony15=[email protected]> wrote:
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Re: QDX
First off, I would like to thank all those that offered help.? Especially Hans.? He recommended I replace the finals.? I did so tonight.? Start up went without any issues, then the LED dimmed and went out.? I was able to restart it, but same thing happened.? Now it will not stay on.?
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I am in no way bashing the QDX, or QRP Labs.? I believe it is builder error.? I do not know what the issue could be.? I see the trash can for this little device unless I can find someone local to help me.? I would buy a prebuild unit over a kit if the opportunity presents itself in the future.
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Thanks
73 KQ4SID
Craig |
Glenn S
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