Re: QDX Modulated CW using FLDIGI
Hi Dan,
fldigi can use QDX transmit CW signal, but because QDX dose not have pulse shaping circuit, if you use it transmit CW, the signal will dirty, so you'd better not do that.
73
|
Evening,
I damaged the pins on one of the rotary encoders and need to get a new one. Anyone know the part number and where I can order one? Does Mouser stock them?
Thanks in advance.
John W9QP?
|
Re: QMX Audio Noise when switching to Digital mode
Thanks Hans. I¡¯m embarrassed to say that I think you identified the issue correctly. After several uses in the field, the Digi mode background noise level seems entirely reasonable.?
I made several screwups in assembling the radio, and while I think I recovered successfully, there is always that little doubt in the back of your head ¡°did I mess something else up and not catch it?¡±
at any rate, it¡¯s ¡°case closed¡± as far as I am concerned.
73, Matt
|
#qmx filter testing and adjustment
#qmx
High-band QMX rev2 (2024), 9V version, Firmware 017.? Powering with a bench supply, limited to 1A at 9V.? Today I made a few FT8 contacts on 20m, with 2.8W power out. That's a good start. I'm very happy to have a working radio, impressed with everything that's been packed into it.
As part of my testing, I've run the BPF and LPF sweeps on 20m, 17m, 15m, 12m, and 10m.? The LPF responses agree reasonably with the the figures in the operating manual. For the BPFs, the 10m, 15m, and 20m filters are pretty good, but 17m and 12m deviate substantially from what's shown in the operating manual.? I'll look at L401 and C401-C404 again, and assuming that I have the capacitors in the correct locations and no soldering problems, is the next step to adjust the spacings of the turns of the coil??
Thanks,
Eric
|
Re: QDX SWR protection circuit?
#qdx
Same issue with traffic lights that control vehicles at intersections. Red/Yellow/Green. The position of these lights, Top/Middle/Bottom is used to understand their meaning. A similar set up could apply to any coloured LEDs in a QDX assuming that it is not a single multicoloured LED.
--
Compton
VK2HRX
Sydney, Australia
|
Re: QDX SWR protection circuit?
#qdx
Hmmm, I wonder whether implementing colored?LEDs as part of a system's Human?- Machine Interface (HMI) could run afoul of the Americans with Disabilities Act (ADA). ?
73 Jim N6OTQ
On Sun, Feb 25, 2024 at 1:18?PM Donald S Brant Jr < dsbrantjr@...> wrote: On Sun, Feb 25, 2024 at 11:46 AM, Colin Kaminski wrote:
My boss is yellow blue colorblind and my coworker is red green colorblind so that limited the colors I could use.?
I ran into the same problem with a MIL SATCOM terminal I was working on.? Since blue-yellow is 1/10th or less common than red-green, which I also have,
we ended up using blue-yellow LEDs and different blink patterns to convey the various device states.??
I was kind of surprised that there was no guidance from the military (that we could find) regarding this issue.
73, Don N2VGU
|
Hi Jim, all
I'm glad to hear that all is well and it is working but I don't really understand what is UNEXPECTED about the way the PTT output is implemented.?
It's clear on the schematic that what is essentially done is an open-drain MOSFET switch for the PTT. And there's a 220-ohm series protection resistor there, just to give some foolproofness to the situation... though - for those people who find that resistance value is too high, personally I wouldn't go building external circuits. If I was confident that the BSS123 would be within spec (170mA) in my application, I'd just remove the 220-ohm resistor and short its pads with a blob of solder!
Also - what other options would I have, for implementing a PTT output, than an open-drain MOSFET? Assuming?that I definitely want to steer clear of relays!
On Mon, Feb 26, 2024 at 12:56?AM Jim Bennett / K7TXA via <w6jhb= [email protected]> wrote: Bojan, Roy, and Chris - thanks for the replies and tips on how to test that the PTT is in fact working. And surely enough, IT IS!! I metered between Tip and Ring and also between Ring and shield - 4.93 volts when I press the key. Most certainly not what most folks would have expected! But, now that I know PTT does function I'll feel safe connecting my SDR++ to the QMX through my MFJ-1708B-SDR box. Now I just need to get CAT-relay working so the QMX and SDR++ talk to each other!
?72/73 & many thanks guys.
--
Jim / K7TXA
Eagle, ID
SKCC 10447T
BUG 301
|
Re: #qmx wrong inductances for LPF?
#qmx
Hi all,
here are my test results and the pleasant final results from the working QMX (20 m - 10 m).
I've made some steps.
1. Checking the uncertainty of measured values for L
I have a set of filter elements to build a high band QDX. I wound some toroids T37-10 following the QDX manual. The measured L were between 10 % and 15 % higher than expected. Maybe I've measured a little bit more than the real value but not 25 % or more like for my T30-17.
2. Checking the validity of values from build LPF
I used a tiny rf test board to build LPF. First I've build the filters from the parts for QDX.
Measurement was done by a VNWA looking at the attenuation at the band frequencies and the first and second harmonic and the match toward the PA.
The measured values were fine. So the setup should be usable.
3. Checking the LPF for QMX
I've build the LPF using the elements for my QMX (again on the tiny test board). The toroids were wound following the manual (L 508 with 11 turns). Measurement was done like in step 2.
LPF 20 m: values usable
LPF 17 m and 15 m: values not good
LPF 12 m and 10 m: values usable
To consider the capacity of the real TX (stray capacity of PCB and capacity from the PA) I've added some 10 pF to the capacitor toward the PA. Here are the results:
LPF 17 m and 15 m: values useable for 17 m and maybe for 15 m
Now I've reduced L 512 also to 11 turns.
LPF 17 m and 15 m: nearly perfect
?
3. Building the QMX following the manual but L 512 with 11 turns, measured output and harmonics
The harmonics were measured using a precise SDR and a spectrum analyzer software. QMX and SDR were coupled with attenuators with an optimized value of attenuation.
The output was 4 ¡ 5 W so ok.
The harmonics suppression was at least 56 dB so more than ok.
?
Finally conclusion: following the manual would be ok, maybe also without the reduction for L 512.
This matches to what Hans wrote in this and in a different thread.
?
73 and wish you success with your QMX
Ludwig
?
|
Bojan, Roy, and Chris - thanks for the replies and tips on how to test that the PTT is in fact working. And surely enough, IT IS!! I metered between Tip and Ring and also between Ring and shield - 4.93 volts when I press the key. Most certainly not what most folks would have expected! But, now that I know PTT does function I'll feel safe connecting my SDR++ to the QMX through my MFJ-1708B-SDR box. Now I just need to get CAT-relay working so the QMX and SDR++ talk to each other!
?72/73 & many thanks guys.
--
Jim / K7TXA
Eagle, ID
SKCC 10447T
BUG 301
|
Re: GPS for frequency calibration?
#qmx
#gps
Thanks Hans for the quick answer.
No problem, the frequency is really accurate. I was fiddling with the QLG2 and found nothing for calibration. But it's not important.
73, Ludwig
|
Re: #qdx QDX and a smoked BS170
#qdx
Evan,
I think your analysis is spot-on correct. The TX pin of the MCU is directly in the line of fire for an overvoltage fault starting at the BS170s.
JZ
On Sun, Feb 25, 2024 at 3:13?PM Evan Hand < elhandjr@...> wrote: James and John,
I have seen this on a damaged Rev 1 QDX that I bought from a Ham that did not want to try to repair it.? At first, the QDX would power up and connect to the PC using PuTTy.? After trying for a few minutes, the connection dropped, and I could not restart the QDX.? The original failure was shorted BS170s that took out IC5.? Since one of the inputs to IC5 is the TX signal direct from the MCU, I assume that 12 volts got to that pin and took out the processor.
The lesson I learned was to remove the BS170s to verify them out of the circuit (I now have a Hakko desoldering gun for this) and verify IC5 before installing fresh units.
73
Evan
AC9TU
|
Re: #qdx QDX and a smoked BS170
#qdx
James and John,
I have seen this on a damaged Rev 1 QDX that I bought from a Ham that did not want to try to repair it.? At first, the QDX would power up and connect to the PC using PuTTy.? After trying for a few minutes, the connection dropped, and I could not restart the QDX.? The original failure was shorted BS170s that took out IC5.? Since one of the inputs to IC5 is the TX signal direct from the MCU, I assume that 12 volts got to that pin and took out the processor.
The lesson I learned was to remove the BS170s to verify them out of the circuit (I now have a Hakko desoldering gun for this) and verify IC5 before installing fresh units.
73
Evan
AC9TU
|
Re: QMX FW 17 and side tone clicks
I can confirm this observation.?However, this does not seem to apply to the interference that occurs when nearby stations are transmitting at the same time.
73!
Simon
|
Have a look at the output of the supply as you plug and un-plug it.?
DC couple and trigger off of the output and you are looking for spikes and excursions during turn on and off.?
Repeat by connecting and disconnecting a load resistor if you have one while the unit stays powered on.? Again, you are looking for anything which indicates lack of stability and good regulation.
Hardest test I saw, a guy dragged a coarse file across the output studs of a (very hefty) power supply; he said if there were any instabilities or oscillations that would trigger them.
Then leave it powered on, AC couple and look for AC hum, switching-related spikes, etc., both with and without load, zoomed in to lower volts/div settings.
73, Don N2VGU?
|
Re: QDX SWR protection circuit?
#qdx
On Sun, Feb 25, 2024 at 11:46 AM, Colin Kaminski wrote:
My boss is yellow blue colorblind and my coworker is red green colorblind so that limited the colors I could use.?
I ran into the same problem with a MIL SATCOM terminal I was working on.? Since blue-yellow is 1/10th or less common than red-green, which I also have, we ended up using blue-yellow LEDs and different blink patterns to convey the various device states.?? I was kind of surprised that there was no guidance from the military (that we could find) regarding this issue. 73, Don N2VGU
|
Re: #qdx QDX and a smoked BS170
#qdx
James, That is a sad and surprising result. At least you have an answer now. JZ
Thank you for your help. I removed the TCXO and L15 and still found 7 ohms to ground on 3v3.?
I never actually thought to put my finger on the MCU as I didn't consider that as a possibility, but alas... it got super hot.?
So sounds like it is the MCU unfortunately. I'll either have to get a new board or new MCU from Hans.?
I'll weigh my options.?
Thanks again.?
James
|
Re: #qdx QDX and a smoked BS170
#qdx
Thank you for your help. I removed the TCXO and L15 and still found 7 ohms to ground on 3v3.?
I never actually thought to put my finger on the MCU as I didn't consider that as a possibility, but alas... it got super hot.?
So sounds like it is the MCU unfortunately. I'll either have to get a new board or new MCU from Hans.?
I'll weigh my options.?
Thanks again.?
James
|
Re: #qdx QDX and a smoked BS170
#qdx
Removing L15 will disconnect the clock generator from 3v3. That might be a good test. I hope it is not the MCU. I have never seen a QDX MCU fail.
JZ
Thanks, John.
I did just remove IC1 and here are my results:
IC1 output pad to ground = 6 ohms.
IC1 isolated gives normal 3.3v output and minimal current draw.
Board current with IC1 removed = 140mA.
I removed IC13 and still measured around 7 ohms to ground.?
12v input to ground = MegOhms.
So it would seem that my short is somewhere on the 3v3 side. Guess I have more digging to do :(
James
|
Re: #qdx QDX and a smoked BS170
#qdx
Thanks, John.
I did just remove IC1 and here are my results:
IC1 output pad to ground = 6 ohms.
IC1 isolated gives normal 3.3v output and minimal current draw.
Board current with IC1 removed = 140mA.
I removed IC13 and still measured around 7 ohms to ground.?
12v input to ground = MegOhms.
So it would seem that my short is somewhere on the 3v3 side. Guess I have more digging to do :(
James
|
Re: #qdx QDX and a smoked BS170
#qdx
James, one more thing...
The event that took out your BS170 may have reached all the way back into the clock generator chip. If you find that the fault is on the 3v3 rail, there is a good chance that it is at the clock generator.
JZ
James, ouch!, that sounds pretty grim! Recall that the 3v3 regulator runs off of the 5v0 rail so in a sense everything runs off of 5 volts and the short could be anywhere. Removing IC1 may help the isolation process.
With a 900 mA current draw, something on that board is probably getting quite hot.? Finger testing the chips might give you an idea where the fault is. Better yet, use an IR camera if you can put your hands on one.
Good luck JZ KJ4A?
I'd like to add a little more info from the troubleshooting I've just completed.
IC5 is still removed.
With IC2 removed, current draw = 0ma. -- I trust this means that my issue lies with something on the 5v rail?
IC2 removed and powered by itself is drawing about 3ma and putting out 5v.?
Q7 removed = 0ma.
Q7 removed and bypassed = 900ma
|
Compton
Donald S Brant Jr