¿ªÔÆÌåÓý

ctrl + shift + ? for shortcuts
© 2025 Groups.io
  1. QRPLabs
  2. Messages
Expanded Topics Messages Polls
Date
Re: QCX CW Filter

 

On Mon, Jan 1, 2024 at 12:10 AM, Peter GM0EUL wrote:
Are you sure there's something wrong with it? In my experience the CW filter on a QCX is very soft compared to my K2 and KX3.
Agree. The first time I used a radio without really sharp filtering it was quite a shock just how much activity I could hear above and below the frequency I was tuned on.?

The QMX is pretty good. I was using my Kanga Rooster yesterday though and there was a cacophony of dits and dahs either side of me.?

These days I don't think anything of it but it is distracting at first, particularly to a newcomer to CW :)

Danny M0SDB?
Re: Happy New Year 2024

 

- ..-
-.. .? -.-. .... .-. .. ...
-- .-? ..- ... .-
--
Chris / W2BPL
Re: QMX order form problem (kit/assembled) #qmx

 

On Fri, May 26, 2023 at 03:25 AM, Iosephus wrote:
How would this kit be compared in difficulty with the truSDX? (My last successful kit)
The QMX is much more complex than the truSDX. There are many more components and the boards are much tighter. There are more complex windings to do as well.?

However, if you have done a nice neat job of the truSDX and assuming you take your time and *follow the instructions TO THE LETTER * you should be fine. Just be aware just how tight some of the components are squeezed in and name sure you have a good soldering iron and a magnifier of some sort to help you.?

The QMX is a more capable radio once finished and requires far less fiddling around tuning all the coils etc as well so it has distinct advantages.?

I have both and the QMX is the one that gets used the most :)?
Re: QMX output power 40 m vs 20 m (JS8Call)

 

SOLVED
After I fixed SWR bridge transformer, output has changed (and increased) on all bands.
With a fully charged Li-Pol battery and dummy load:
80 meters: 6 W out
60 meters: 6.5 W out
40 meters: 5 W out (~5.2 est. on 20 W scale)
30 meters: 5 W out (~5.1 est. on 20 W scale)
20 meters: 4.5 W out
Obviously, I have to think about the Si diode trick for a fully charged battery. Optimum supply voltage seems to be 11 volts, only 5 MHz output is then 6 watts, the rest is 5 watts or less.
73, de Jindra OK4RM
Re: QMX SWR meter gone mad

 

I don't see how there can be any confusion.? Each end of the 10 turn winding has a wire that comes out of each end of the toroid and there is a hole for the 10 turn winding next to it. The obvious thing is to solder that wire into that hole.? Are people really deciding to loop both ends of the 10 turn wire back over the toroid and into the hole at the other end?
The pictures and text on section 2.14 of the assembly manual show this clearly.? The binocular toroid with the 10 and 1 turn pairs coming out of the toroid, not coming over the top.

Chris G5CTH
Re: QMX SWR meter gone mad (SOLVED)

 

P.S. now I realized that in Power/SWR display the TOP bar is power and the BOTTOM bar is SWR (BTW I think this is not explained in Operation manual). With my SWR transformer screwed the top bar was very small (1-3 pixels wide in the first rectangle) while the bottom was showing "full throttle" - it was the SWR! Now it is exactly opposite: top shows full output, bottom remains empty when transmitting into dummy load.


On Mon, Jan 1, 2024 at 11:56 AM, ok4rm wrote:
Hello, Adrian, thanks for the link!
I checked the windings. They look the same as in NorCal power SWR meter as well as the photo in assembly manual.
So then the only other possibility was that one end of one of the 10-turn windings, the ground connection, had no contact. When I looked in the schematic diagram, this seems to be the only possibiity, because then all continuity testing goes through other windings and there is apparent break in any of the windings.?
I gave all solder points some more heat, for the 10-turn windings I added a micro droplet of solder and heated the hole until I noticed that the solder was sucked in - this means that the enamel insulation has burned and the "naked" copper surface accepted the solder.
And voil¨¢ - dummy load shows SWR almost 1 (it gets worse towards higher frequencies, but still shows something about 1.17 at 14 MHz).
Uff, I am so happy :-D

73 + HNY de Jindra

On Mon, Jan 1, 2024 at 11:10 AM, Adrian YO3GFH wrote:
Ahoj!

I found a bit clearer description of the SWR bridge winding process in the Norcal powermeter assembly manual, page 10:



You should also check if the 1 turn windings are as far as possible away from the 10 turn ones.
Hope it helps!

HNY!
YO3GFH
op. Adrian
Re: QMX SWR meter gone mad (SOLVED)

 

Hello, Adrian, thanks for the link!
I checked the windings. They look the same as in NorCal power SWR meter as well as the photo in assembly manual.
So then the only other possibility was that one end of one of the 10-turn windings, the ground connection, had no contact. When I looked in the schematic diagram, this seems to be the only possibiity, because then all continuity testing goes through other windings and there is apparent break in any of the windings.?
I gave all solder points some more heat, for the 10-turn windings I added a micro droplet of solder and heated the hole until I noticed that the solder was sucked in - this means that the enamel insulation has burned and the "naked" copper surface accepted the solder.
And voil¨¢ - dummy load shows SWR almost 1 (it gets worse towards higher frequencies, but still shows something about 1.17 at 14 MHz).
Uff, I am so happy :-D

73 + HNY de Jindra


On Mon, Jan 1, 2024 at 11:10 AM, Adrian YO3GFH wrote:
Ahoj!

I found a bit clearer description of the SWR bridge winding process in the Norcal powermeter assembly manual, page 10:



You should also check if the 1 turn windings are as far as possible away from the 10 turn ones.
Hope it helps!

HNY!
YO3GFH
op. Adrian
Re: QMX Rev2 80m RF sweep good enough? #bpf #filter #qmx #80m

 

Jim,

Thanks for your advice. I decide to leave it there for now. I might try the adding capacitor method when I feel it's necessary.

73 de Lun BD8BTE
Re: QMX SWR meter gone mad

 

Ahoj!

I found a bit clearer description of the SWR bridge winding process in the Norcal powermeter assembly manual, page 10:



You should also check if the 1 turn windings are as far as possible away from the 10 turn ones.
Hope it helps!

HNY!
YO3GFH
op. Adrian
Re: QMX SWR meter gone mad

 

I checked continuity and all four connections are OK.?
So when I look at the schematic the most likely error is 10-turn winding orientation (A-A and D-D). The assembly manual does not specify winding orientation and honestly, I was not sure which direction is right. That could probably explain "infinite SWR" when connected to the dummy load.
OTOH why it shows more or less reasonable SWR with real antenna is a mystery...
73 Jindra
Re: Questions re: PA socketing and Zener & L14 diodes

 

Here's a description with image of how I installed Zener diodes on my two QDX'es. The minus goes to the Drain and the plus end of the Zener goes to ground.?

73

--
Sverre

LA3ZA
http://la3za.blogspot.com
QMX SWR meter gone mad

 

Hello,
my self-built low-band QMX works fine with EFHW antenna on 40 and 20 meters. It usually switches on SWR protection on 80 meters.
I measured the actual SWR performance of the antenna at the connector in ham shack by VNa and got this:

80 m: SWR < 3 at frequencies above 3535, dip at 3684 (1.07)
40 m: SWR < 2 everywhere in the band, with a dip at 6844 (1.43)
20 m: SWR <1.8 under 14100, <2 in the whole band, dip at 13749 (1.36)
SWR protection seems to be working accordingly, except some glitches at 40 and 20 meters when it occasionally blocks TX without apparent reason.

However, I am shocked when see results of SWR sweep:
20M:

10 |.? ?***.? ? ?.***? ?.***? ? ? .? ? ? *|? **? .? ? ?*.? **50%*

? ?|.? ?*? *? ? ?*? ?*? .*? ? ?.? ? ?.*? ? ?.? ? ? *? ? ?*? **? .? ? ?*.? *? .

9.0|.. .*. * . . * . * .*. . . . . . .*. . ... . . * . . * * * ... . .*. .*. . .

? ?|.? ?*? *? ? ?*? ?*? *? ? ? .? ? ?. *? ? .? ? ? *? ? ?* * *? .? ? ?*.? *? .

8.0|.. * . .*. . * . .*.*. . . . . . . * . ... . . * . . |** * ... . .*. * . . .

? ?|.? *? ?.*? ?*.? ? **.? ? ? .? ? ?. *? ? .? ? ?*.? ? ?|** *? .? ? **. *? ?.

7.0|.. * . .*. .*. . .**.. . . . . . . .*. ... . .*. . . |*. .*... . * * * . . .

? ?|.? *? ?.*? ?*.? ? **.? ? ? .? ? ?.? *? ?.? ? ?*.? ? ?|*? ?* .? ? * * *? ?.

? ?|.? *? ?. *? *.? ? ? .? ? ? .? ? ?.? *? ?.? ? ?*.? ? ?|? ? * .? ? * * *? ?.

6.0|..*. . . * .*. . . ... . . . . . . . * ... . .*. . . | . .*... . * **. . . .

? ?|* *? ? . *? *.? ? ? .? ? ? .? ? ?.? ?*? .? ? ?*.? ? ?|? ? * .? ? * **? ? .

5.0|*.*. . . .** . . . ... . . . . . . . * ... . .*. . . | . .*... . * **. . . .

? ?|.*? ? ?.? ** .? ? ? .? ? ? .? ? ?.? ? * .? ? ?*.? ? ?|? ? * .? ?*? *? ? ?.

4.0|.* . . . . . . . . ... . . . . . . . . *.. . .*. . . | . .*... .*. . . . . .

? ?|.*? ? ?.? ? ?.? ? ? .? ? ? .? ? ?.? ? ?*.? ? * .? ? ?|? ? ?*.? ?*? .? ? ?.

? ?|.? ? ? .? ? ?.? ? ? .? ? ? .? ? ?.? ? ? *? ? * .? ? ?|? ? ?*.? *? ?.? ? ?.

3.0|.. . . . . . . . . ... . . . . . . . . ..* . * . . . | . . *.. * . . . . . .

? ?|.? ? ? .? ? ?.? ? ? .? ? ? .? ? ?.? ? ? . *? * .? ? ?|? ? ?*. *? ? .? ? ?.

2.0|.. . . . . . . . . ... . . . . . . . . ... **. . . . | . . .***. . . . . . .

? ?|.? ? ? .? ? ?.? ? ? .? ? ? .? ? ?.? ? ? .? ? ? .? ? ?|? ? ? .? ? ? .? ? ?.

1.0|.? ? ? .? ? ?.? ? ? .? ? ? .? ? ?.? ? ? .? ? ? .? ? ?|? ? ? .? ? ? .? ? ?.

? ? ----------------------------------------------------------------------------

? ? 6? ? ? 7? ? ?8? ? ? 9? ? ?10? ? 11? ? ?12? ? ?13? ? 14? ? ?15? ? ?16? ? 17

(shows SWR 8 at 14000 and then drops down in steep slope to something just under 3)

40M
10 |****? ?.? ? ? ? ? ? ?|? ? ? ? ? ?****? ? ?50%
? ?|? ? ? ? ? ?.? ? ? ? ? ? .? ? ? ? ?** .? ? ? ? ? ?* |? ? ? ? ? ?*. *
9.0| . . . . . . . . . . . ... . . . . * . . . . . .*.*| . . . . . *..*. . . . .
? ?|? ? ? ? ? ?.? ? ? ? ? ? .? ? ? ? ? ?*.? ? ? ? **? *|? ? ? ? ? ?*.? *
8.0| . . . . . . . . . . . ... . . . . .*. . . . * * .*| . . . . .*... * . . . .
? ?|? ? ? ? ? ?.? ? ? ? ? ? .? ? ? ? ? ?*.? ? ? ?*? ? ?*? ? ? ? ? * .? *
7.0| . . . . . . . . . . . ... . . . . .*. . . .*. . . |*. . . . .*... * . . . .
? ?|? ? ? ? ? ?.? ? ? ? ? ? .? ? ? ? ? ? *? ? ? *? ? ? |*? ? ? ? ?* .? ?*
? ?|? ? ? ? ? ?.? ? ? ? ? ? .? ? ? ? ? ? **? ? *? ? ? ?| *? ? ? ? * .? ?*
6.0| . . . . . . . . . . . ... . . . . . . * .*. . . . | **. . . .*... . * . .*.
? ?|? ? ? ? ? ?.? ? ? ? ? ? .? ? ? ? ? ? . * *? ? ? ? ?| * *? ? ?*? .? ? *** * *
5.0| . . . . . . . . . . . ... . . . . . . * * . . . . | . * . . * ... . . * * *
? ?|? ? ? ? ? ?.? ? ? ? ? ? .? ? ? ? ? ? .? *? ? ? ? ? |? ? *? ? *? .? ? ? ?*? *
4.0| . . . . . . . . . . . ... . . . . . . . . . . . . | . . * .*. ... . . .*. .
? ?|? ? ? ? ? ?.? ? ? ? ? ? .? ? ? ? ? ? .? ? ? ? ? ? ?|? ? ? ***? ?.? ? ? ?*
? ?|? ? ? ? ? ?.? ? ? ? ? ? .? ? ? ? ? ? .? ? ? ? ? ? ?|? ? ? ? ? ? .? ? ? ?*
3.0| . . . . . . . . . . . ... . . . . . . . . . . . . | . . . . . ... . . . . .
? ?|? ? ? ? ? ?.? ? ? ? ? ? .? ? ? ? ? ? .? ? ? ? ? ? ?|? ? ? ? ? ? .
2.0| . . . . . . . . . . . ... . . . . . . . . . . . . | . . . . . ... . . . . .
? ?|? ? ? ? ? ?.? ? ? ? ? ? .? ? ? ? ? ? .? ? ? ? ? ? ?|? ? ? ? ? ? .
1.0|? ? ? ? ? ?.? ? ? ? ? ? .? ? ? ? ? ? .? ? ? ? ? ? ?|? ? ? ? ? ? .
? ? ----------------------------------------------------------------------------
? ? ? ? ? ? ? ?4? ? ? ? ? ? 5? ? ? ? ? ? 6? ? ? ? ? ? ?7? ? ? ? ? ? 8
(roughly 7.5 at 7000 and drops in steep slope to about 3.8 near 7300)

80M sweep shows flat response at high SWR (10)

However, the most shocking result is shown with a dummy load: high SWR flat over all the frequencies...

What puzzles me is that SWR protection apparently detects the real SWR during regular transmit but "measures" absolute garbage in SWR sweep.
When transmitting into dummy load,
80m (3525 KHz): Power/SWR meter shows full power + some SWR (3 pixel bars) and activates SWR protection as I stop transmission.
60m (5355 KHz): practically the same as 80 meters?
40m (7025 KHz): SWR protection activated immediately, not TX at all
30m (10106 KHz): normal TX, power meter shows full power with some SWR slightly >1 (two pixel bars)
20m (14020 KHz): power meter shows nothing in teh power bar, 1 pixel bar in SWR indicator. Activates SWR protection after short time

What could be wrong? The PCB is quite packed so I am not sure where to start diagnostics. Maybe I should rewind SWR transformer?

73 Jindra

?
Happy New Year 2024

GIUSEPPE
 

Happy New Year everyone?from 20 degrees of brilliant Calabria

Giuseppe iu8eun
Re: QMX HI Band Rev 2. Immediate current limit on startup

 

Sorry, I sent this before reading the earlier message saying much the same¡­
Re: QMX HI Band Rev 2. Immediate current limit on startup

 

Could it be ESD perhaps?
I always use a static grounding wrist strap.
Re: QDX finals modification, imbalanced heating

 

The TN0106 is the 60V version of TN0110. It would
?also work well but you¡¯d want to install a snubber diode for protection against the higher kick. Both devices will produce a higher kick voltage than the BS170.

Please follow Evan¡¯s instructions for troubleshooting the ACT08. The voltage difference you measured at the driver inputs is suspicious. Without that device on the board, I¡¯d expect the DC averages to be nearly identical. I hope you can dig out that scope as it¡¯s the best way to verify the duty cycle and voltage swing.

Tony - AC9QY

On Sun, Dec 31, 2023 at 3:53?PM Peter Li <chinasaurli@...> wrote:
Thanks Tony! Grateful to you for pointing out the TN0110! I see discussion also of TN0106, but I suppose there's no?reason to prefer that over TN0110 other than price/availability? I received the TO-92 hat heat sinks; they're not great, but I'll try attaching them with thermal glue.

On the imbalance... I went ahead and ordered a new IC5 74ACT08 and plan to try that. But if there are other things I can check first it would be good to know. I have a tinySA on the way, which seems worth at least a quick look if it arrives in good time. I wonder if there's any suggestion about why I also see imbalance at the IC5 input. Could it be the IC5 damage shows up as bad input impedance? If it turns out I have problems further upstream?I will probably go to plan B of building a new QDX with the extra kit I have on the shelf...

On Sat, Dec 30, 2023 at 10:39?PM Tony Scaminaci <tonyscam@...> wrote:
Hi Peter,

I like what you¡¯ve done so far. Keeping the TN0110 leads as short as possible is in line with many comments that the leads conduct most of the heat away from plastic TO-92 packages. The Raspi black-finned heat sink is also a good idea to help improve heat transfer from the board itself. Finally, the metal transistor hats will be a plus but likely marginal. Still, I¡¯d do this too. There are copper finned heat sinks in the Raspi form factor that would be better than black aluminum so you might want to look into these as well.

Using black paint will not help at all and will probably decrease heat transfer. Not a good idea, I¡¯d scrape off that paint.

The TN0110 will produce a larger voltage kick at turn off than the BS170 but TN0110 is a 100V device compared to 60V for the BS170 so you have considerably more safety margin. However, the lower gate threshold of the TN0110 will produce a higher drain current which is why you get a higher voltage kick at turn off. I¡¯d go with one of the diode bypass methods offered in this forum for a better safety margin even though it¡¯s probably not necessary.

Some here have experimented with cranking the gate driver AND¡¯s up to 6V. While this will help drive the BS170 to be a better switch, I doubt this would help at all with the TN0110 so don¡¯t bother with that mod. The TN0110 is already a better switch since its gate threshold is lower.

Finally, the imbalance you¡¯re seeing could be due to mismatched transistors with different thresholds. I intend to match my TN0110¡¯s with a DC threshold measurement using a superstrip breadboard. But investigate the other possibilities suggested here first. A scope on those gates would be very useful for troubleshooting this if you can get your hands on one.

Overall, you¡¯re doing great with these mods and keep up the feedback. We¡¯re rooting for you!

Tony - AC9QY

On Sat, Dec 30, 2023 at 2:42?PM Peter Li <chinasaurli@...> wrote:
Thanks Bruce! Once I have the finals imbalance sorted out I will try adding the hats and report back if I have anything useful to add.

Re: QDX finals modification, imbalanced heating

 

Peter,

It is an indication that the waveform is at half the 3.3-volt supply.? It could be a constant voltage or any waveform that has 1.65 volts on average.? The only way to be sure is to verify a decent 50% duty cycle squarewave with 3.3-volt peaks.

73
Evan
AC9TU
Re: Clock with QLD2 - Voltage Regulator #clock

 

It definitely looks like the regulator? went out. there is a bulge on the input side. As Bruce noted I am lucky the ground didn't burn as that probably would have sent? supply voltage to my brand new clock .

I see little lm317 regulators already on a board on amazon for a few bucks but wonder if a buck converter would be a better choice.??

while running this clock? on a little 5v wall wart in the shack is just good enough, I just think it would be great to be able? run the clock on emergency power (aka 12v).?
--
regards,
Bryan, N0LUF
Re: QCX CW Filter

 

Agree with GM0EUL, it is an analog filter with skirts (IIRC) of ?-12 dB/octave, so a signal 350 Hz higher or lower would be only 12db quieter, and therefore adjacent strong signals will still be very audible.?
Re: QDX finals modification, imbalanced heating

 

Thanks Evan! I really appreciate everyone's willingness to help me despite my non-standard setup. If it is #1, I hope that isn't likely to lead to #3 the more I run it in this state. I'll try to get the scope dusted off, but shouldn't just checking with the DC voltmeter be enough to confirm that with IC5 removed IC11 looks more balanced (or not)?
27741 - 27760 of 141945