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Re: #QMX #SSB #calibration A note about spurious PA power after IMD optimization on a band is over
#qmx
#ssb
#calibration
For my test, I was watching the output on an oscilloscope.? It clearly turned off at the end of each test.? ?I didn't even glance at the front panel, so I can't say if the power meter there stuck on a non-zero value.
Stan KC7XE? |
Re: QMX+ high pitch noise on power. Now dead.
Next I would measure the voltage at each of the three terminals of IC101, the 3.3V regulator, when you press the power-on button.? ?But don't press the button for more than a second or so, since it could cause more damage, since it does not appear that you have a way to limit the current.?
?
Also, do you have a way to measure the input current, with more resolution than that ammeter on your power supply? It looks like it is going up to almost 1A, but I'm sure it is not accurate at that range.? If there is not an internal power short, it should only read about 200mA while pressing the button.?
?
Your symptoms indicate that you probably have a failure in your 3.3V power supply (or a device that is connected to) such that the processor can't power-on and set the power to stay on.
?
Stan KC7XE? |
Re: Figuring out why no keyer sound and updating my QMX Menu Reference to Firmware 1_01_003
CW Keyer ? ? ? ? ? ? ? ? ? ? ?| ?||| ?CW Decoder ? ? ? ? ? ? ? ? ? ?| ?||| ?CW passband ? ? ? ? 300 ? ? ? | ?||| ?CW center ? ? ? ? ? 700 ? ? ? | ?+|| ?Auto-offset/tone ? ?YES ? ? ? | ? || ?CW offset ? ? ? ? ? 700 ? ? ? | ? || ?Sidetone frq ? ? ? ?700 ? ? ? | ? || ?Sidetone volume ? ? 60 ? ? ? ?| ? || ?Sidetone abs/rel ? ?Absolute ?|? I reset it back to Absolute ? || ?Choose filters ? ? ? ?? |
I measured the frequencies used for phase calibration on my rev 1 QMX 80-20.? For 80, it is 3.560MHz; 60, 5.346MHz; 40, 7.061MHz; 30, 10.123MHz and 20, 14.061MHz. The settings of the band configuration have no effect to the frequencies used, it is most likely that when one fiddles with those settings, they are running a lot of phase calibrations, and it just happens to work one of those times. My QMX never finishes phase calibration on any band, only getting about 1/3 done before it aborts.?
Gary
W9TD |
Re: #QMX #SSB #calibration A note about spurious PA power after IMD optimization on a band is over
#qmx
#ssb
#calibration
Nothing special Stan. Ran the calibration steps in sequence, one by one, using 'O', '+', 'O', '+', etc. Will run again and measure the power out in the dummy load for each IMD test (so far have only looked at the pwr indicator on the display, showing 1-4 bars at the end of each test, and back to zero bars if I CTRL+Q).
?
The unit is a rev 1, assembled by me, works perfectly on all bands otherwise (CW only tested), with out power between 2.8W and 5W at 11.6V.
?
72/73 de Enzo M0KTZ |
Re: QMX won’t power up
Can you measure the current draw from your power supply to the QMX in the following three conditions:
1 - while QMX is powered off (remove power cord, then replace it to make sure QMX is off).
2 - while you are pressing the power-on button?
3 - after you release? the power-on button (which is when it should be powered on).
?
That will help determine what state your QMX is in. |
Turning the EQ on and maxing it out to +20 took care of my distortion problem. Also tried the QRP Guys microphone and everything seems to be working. Before that it was unusable.?
I now show power out and have made contacts from San Diego to Kentucky.
I need to try it on my QMX+ now. The test I just ran is on a QMX 20-10. Not going to calibrate again. It’s been calibrated multiple times.? Im running the mic gain at 63 and compression at 5. |
Figuring out why no keyer sound and updating my QMX Menu Reference to Firmware 1_01_003
I updated my QMX and in the process I get no sound during practice.? It is sending but there is no volume.
any ideas as to the issue?? Has to be a new setting.
?
In the process of figuring this out I am updating my QMX Menu Reference. |
Re: Power Output
On Fri, Mar 28, 2025 at 06:19 PM, paul G0HEU wrote:
is there any way I can “smooth” this out a little, drop 160m down and increase 6m ???You can only do this balancing act with bands which share a lowpass filter.? Otherwise, it is mostly the output transistors (and I suspect their drivers, which have to drive their gate capacitances) losing "oomph!" at the higher bands.? Component losses and parasitics are worse at low VHF as well. 73, Don N2VGU |
Re: #QMX #SSB #calibration A note about spurious PA power after IMD optimization on a band is over
#qmx
#ssb
#calibration
Enzo, I checked a couple of IMD optimizations on my QMX, and this does not happen.
Others should check.
Anything else special about your setup or the sequence of test steps you did? Stan KC7XE |
QMX+ Beacon mode
Decided that seeing I have the GPS installed, to revisit beacon mode. Setup all the parameters including frequency 14097.200. Well it seems to Beacon OK...I can see that it is transmitting. Problem is ...it is not on 14097.2....in fact I have no idea if it is even on 20m. Bit of a glitch here ?
de VK6XT? |
Re: QSX project retirement
On Fri, Mar 28, 2025 at 03:14 PM, Muhsin TA1MHS wrote:
I've wondered if the second stage of the 10W linear could be hooked into the QMX between the existing PA and the LPFs, sort of where T501 is.? T501 would become two transformers, one would provide the drive for the PA stage, the second would manage the impedance transform to the existing LPFs. |
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