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Re: QMX USB-C compatibility - improved via ugly hack

 

Giuseppe, I am sorry for the failure of your QMX. There are threads on how to fix failures caused by accidentally disconnected Power supplies. Look for those threads, they had been active the last days.

Yes, I installed the two resistors, see attached picture. Everything worked well after that mod.

Good luck with the repair!

73 Frank DD4WH?
Re: QMX USB-C compatibility - improved via ugly hack

GIUSEPPE
 

good morning Frank, did you manage to solder the 2 resistors on the USB C socket of the PCB?? Unfortunately I was unlucky with the QMX, it no longer works, it was recognized as a USB peripheral by my PC for a few seconds until the power cable accidentally came off and it turned off, you know then it is no longer recognized by any PC , only the display with 2 lines of squares turns on when I press the left encoder and then turns off when released.? Good luck.? with your QMX, 73

Giuseppe iu8eun

Il Ven 27 Ott 2023, 17:02 DD4WH <dd4wh.swl@...> ha scritto:
Just to confirm the observation by others:

After installing the pull-down resistors, I can now use a simple USB-C cable directly to connect the QMX to my smartphone ! (without the need for an OTG cable, or USB-A to USB-C adapters).

Andrew, thanks again for finding out about this and thanks Guiseppe, for showing where to install the resistors.

Just for reference:

This is the view from the underside of the PCB (where the pins are soldered to the PCB):

----------------------------- this is the outer edge of the PCB

O????????????????????????????? O ? these are two oval holes

O ? o o o o o x o o??? O?? these are two oval holes and the first row of USB-C jack connectors
? ? ? o o x o o o o o???????? this is the second row of USB-C jack connectors

The pins marked with an x should be connected to a 5K1 resistor that is connected to GND at the other end.

73 de Frank DD4WH

Re: QDX FT8CN issue

 

Please enter in the topic search: qdx ft8cn.
Read the messages that appear.
I'm sure you'll find a solution.
--
Gyula HA3HZ
Re: QCX Challenge - October 2023

 

sporry I will not be QRV this time.

73's and have fun
Martin
DK3UW
Re: Buck Converter Confusion

 

I put a 1000uf capacitor at the output to absorb the spikes. Very quiet then.
Gary
W9TD
Re: 50w PA suddenly making QCX+ reset with key contacts close #50w #80m #50wpa #amplifier

 

Mr. Akhurst,

Yes, I had the QCX-mini running off a battery, in practice mode, but just in case, had it connected to the QRP Labs Dummy Load (love that little thing).
The PA was getting the PTT signal from the QCX-mini, signal in from the Signal Generator, and running out into a substantial 200 Watt 50 ohm dummy load.? Actually, had a power meter on output of the PA then into the dummy load.? thanks.?? Problem turned out to be the buck converter powering the QCX+, not the PA.
Eric
Re: #qmx High bands 20, 17, 15, 12, 11, 10m now available #qmx

 

Amateur radio is under Part 97, not 95.

-=-=-=-=-=-=-=-=-
73,
Gwen, NG3P
Re: 50w PA suddenly making QCX+ reset with key contacts close #50w #80m #50wpa #amplifier

 

¿ªÔÆÌåÓý

Mr. Strohm,

You were spot on that it was not the PA. ?The power supply actually handles it all fine, what failed was not anything with the PA, as you surmised (well done), but the Droc buck converter I was using for almost a year to supply the QCX + with 12 volts from the 21 volt power supply to the PA. ? Has worked fine for a year but something in the buck converter failed. ?When you key the QCX + as soon as it pulls current from the buck converter, the converter voltage drops from 12 vdc to around 0.5 vdc¡­.way too low for the QCX+ to operate. ? ? Thank you. ? ?All running fine now with PA off the power supply and QCX+ off a battery.

Will try to fix the buck converter¡­. will also build my own using Hans¡¯ advise to use a 7812 regulator in TO-220 pkg with heat sink and a couple capacitors to provide 12 vdc at 1.5 amp (max).

Cheers
Eric?
Re: QDX power and RF Sweeps...Tweak? Leave alone?

 

I should have mentioned that the same applies to the 60/40 meter tradeoff.

73
Evan
AC9TU
Re: QDX power and RF Sweeps...Tweak? Leave alone?

 

Hello Nate,

I have built 5 QDX and repaired a few others.? My experience would agree with Ryuji on L12 but differ on the LPF toroids.? Here is a picture of the first QDX that I built (and repaired multiple times):


The reason for the picture is to show the adjustment to L4.? I got to this arrangement by balancing the power out between 20 and 30 meters.? When the windings were evenly spaced, I had high power on 30 and low power on 20.? With this arrangement, they are about equal at about 4 watts.

Hans has a YouTube video on what he does to adjust the LPF for the QCX series of transceivers.? You can ignore adjusting the "resonant" coil as the QDX is a class D and not a class E amp, where an inductor is used to tune the output stage.? Otherwise, it is the following process to adjust the LPF for the best output between the two bands shared by the LPF.? Note that the QCX uses three inductors in the LPF vs only two in the QDX.? The process is still similar.



73
Evan
AC9TU
Re: Source for wire in USA

 

¿ªÔÆÌåÓý

This time I got 155 deg wire. We'll see how it goes. Nice one can buy small amounts if desired.

73,
Cliff, AE5ZA



On Oct 27, 2023, at 22:16, Tisha Hayes, AA4HA <Tisha.Hayes@...> wrote:

That is where I usually buy my coil wire from. Some of it is made by Essex; I get the wire with?Aromatic Polyimide insulation that has a 240 C rating. The temperature rating does not matter that much to me but the coating is very durable. You may find it difficult to remove the insulation.

I use it for more than just QRP Labs kits.



Even buying one spool, there would be enough wire to make a few hundred kits.

--
Tisha Hayes, AA4HA

Re: Source for wire in USA

 

That is where I usually buy my coil wire from. Some of it is made by Essex; I get the wire with?Aromatic Polyimide insulation that has a 240 C rating. The temperature rating does not matter that much to me but the coating is very durable. You may find it difficult to remove the insulation.

I use it for more than just QRP Labs kits.



Even buying one spool, there would be enough wire to make a few hundred kits.

--
Tisha Hayes, AA4HA
Re: QDX power and RF Sweeps...Tweak? Leave alone?

 

Many RF guys are busy working on something else in the past few days... that's why the response isn't coming.

All your bands seem to be on the lower slope of the BPF peaks. So, you could squeeze and make the windings a bit tighter on L12. I would start with 20m and work downward, one band at a time.

On your 20m LPF, you might want to make sure the inductor windings are equally and evenly spaced out using the entire toroids. Also move the 20m LPF core (the longitudinal direction one), if possible, so that it is not touching or too close to the next core. But I'd do these things only if it's easy to do so. Wouldn't go too far otherwise, since these look pretty ok anyway.
Re: U4B balloon tracker - output frequency makes no sense?!?

 

Hi Rob when you did a factory reset it deletes the program called TRACKER so you have to make it again in the monitor program?
File manager? press F for new file type TRACKER
File manager select TRACKER? edit?
Type in the program?
10 GPS 300
?TELE?
?GOTO 10?
Then control c to compile?
if you want to try something different you can produce a balloon glyph before your transmissionas shown on the wsjtx waterfall in example below? by using the following program and it will look something like the image attached

10 GPS 300
?CW 0 14096860 5 0 "*01IFLCNAP8Q7R6R5S0S0S5R6R7*"
?CW 0 14096872 5 0 "*0155? 36396303? 6819090815*"?
?TELE?
?GOTO 10?
Dave VE3KCL
Re: #qmx High bands 20, 17, 15, 12, 11, 10m now available #qmx

 

Muhsin,?
Thanks for the info.?
I still am not sure about the legality of digital modes under FCC part 95.
I think I'll just stick to 10 meters.?

Randy, K5HJ
Re: U4B balloon tracker - output frequency makes no sense?!?

 

Hi Rob?
You have to put in your callsign? and the band and have? a look at what channel you are using ( there are 3 channels and one of them can be selected)?
The channel selection sets the timing of the transmission of the U4B and the type of telemetry code.
What channel did you select?
You also have to make a gps antenna and solder it to the gps pins before it will calibrate properly.... I assume you did that correctly.
What I do is put a 50 ohm load across the antenna pins and run the radio near my ham receiver with one side of the load resistor connected to a small alligator clip wire.
I have never tried to operate to operate a cw command at low frequencies below the 80 meter band ..?
If I understand you correctly, you say you asked it to command a cw tx at 65khz...... for a balloon transmitter that is a very long resonant antenna.... it is really made for balloons at 10mhz? and higher frequencies due to the length of the antenna hanging from the balloon as far as I know it has not been tested at such low frequencies and was not designed to transmit in that range..
I would do a factory reset and try this command which should make a part balloon glyph on your wsjtx screen below the 20m wspr band
CW 0 14096860 5 0 "*01IFLCNAP8Q7R6R5S0S0S5R6R7*"
?see how this works
Dave VE3KCL
?
Re: QCX + Display troubleshooting

 

Hi John. Sounds like it¡¯s giving you fits. I¡¯ll email you privately. 73¡­ Ron

On Fri, Oct 27, 2023 at 14:25 John Schreiner <jskcs1@...> wrote:
I soldered R47 contacts and had good contact on the ground pin from R47 to the Voltage regulator heat sink ground connection on other board.

I measure the resistance range of this R47 at min - 73 ohms and at max turn clockwise -0 125 ohms..thats the range I see..I dont see it go to zero
I also notices the VR getting warm, so I attached the back enclosure with nut to help as a heat sink.

I measured all the microcontroller pin voltages. I also see the display only flickers now and then goes to black..no back light staying on like before.

And then I see my meter telling me its pull 0.47A at 13.24V...and the enclosure was getting warm too...so I pulled the plug for now.

So, what is your rate and address for an ER visit LOL!!??
Thanks
John-N2LK

Re: #qmx #troubleshooting New QMX troubleshooting advice? #qmx #troubleshooting

 

?Nick,

I assume that the 3.3V SMPS board hasn't started and the 3.3V power is still coming from the 3.3V linear regulator, hence the diagnostics saying 'Linear'.

This suggests that LIN_REG_EN is not telling Q101 to switch off the linear regulator IC101 allowing the SMPS to take over. So, I'd check the LIN_REG_EN voltage, IIRC it should be a little below supply voltage. It could be as simple as the connection on the board connector.

I don't know if that would explain the lack of any display on the LCD but the processor knows the SMPS hasn't started so may stop doing anything until it is.

Hope this help.
Simon
G0FCU.
Re: QCX + Display troubleshooting

 

I soldered R47 contacts and had good contact on the ground pin from R47 to the Voltage regulator heat sink ground connection on other board.

I measure the resistance range of this R47 at min - 73 ohms and at max turn clockwise -0 125 ohms..thats the range I see..I dont see it go to zero
I also notices the VR getting warm, so I attached the back enclosure with nut to help as a heat sink.

I measured all the microcontroller pin voltages. I also see the display only flickers now and then goes to black..no back light staying on like before.

And then I see my meter telling me its pull 0.47A at 13.24V...and the enclosure was getting warm too...so I pulled the plug for now.

So, what is your rate and address for an ER visit LOL!!??
Thanks
John-N2LK
QDX power and RF Sweeps...Tweak? Leave alone?

 

Got my QDX built! This will be my first HF transceiver, assuming I pass my General tomorrow!

I took some measurements, and would like some opinions on if I should adjust anything and how/which way to go. (I'm not sure which way squeezing or spreading turns moves the frequency cutoff, for example.)?
This is a 9V QDX, operating into the QRP-labs dummy load. (So there's a diode and capacitor on it as well for measuring DC V with a DMM)? Pics of the RF sweeps and my board and L12 closeup attached.?

? Watts @ 9V RF Filter sweep, -db @ default freq
80m 4 -8 ? ?
60m 4.6 -16 ? ?
40m 3.7 -3 ? ?
30m 4.2 -9 ? ?
20m 3.3 -5 ? ?

Power looks OK, but maybe a tad low on 20m??
I'm concerned that most of the LPFs show too high a frequency peak.... and 60m is down 17db at the default frequency.?
I do have a NanoVNA, if there's something I can do there to look at inductors, and I do have some extra 28ga wire if I need to re-wind something. (From having to buy 2 boards thanks to a soldering screw up)

What would you do? Nothing? Tweak the 20/30m LPF inductors? Rewind L12??
Why would 60m show good power but low RF filter sweeps? L12 problem?

RF Sweeps:



L12 and overview:









Thanks for any help or thoughts!

-Nate
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