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Re: 80m QCX mini for sale

 

Hi John
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Yes, still available. Maybe you could phone me to discuss or send me an email. My email address seems to have been truncated on my post...it's correct on my QRZ.com page.
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73 Steve G4EDG?
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07981 950650
Re: New kit just stopped working after unplugging the power

 

Hello, I'm back again and this time I have good news, I think I finally fixed everything.
Once connected to the terminal app, touching the board or "bending" it slightly changed the voltage, so as you suggested I once again checked for cold joints or anything like that.
In fact it was the DC connector that had a bad connection, only one of the 2 grounds was "touching" the connector.
I picked a new DC connector on a old arduino and now it works like a charm !
I even made my first CW contact this morning !
Thanks again to all of you for the precious help.
Now that this one is working I'm wondering how much time I will hold before ordering a new kit, as it is so much fun :D
Re: Wall warts can be fatal to QMX :-(

 

I normally use one of my many, very good linear lab supplies. I was readying a 2nd QMX I bought to lend to an old USAF diddybopper living in a memory care facility. An adjustable lab supply was not a practical PSU in his situation, particularly as I'd have no way of preventing the voltage from being changed by accident.

So I thought a wall wart would do as all I needed was 100 mA for Rcvr operation. Bill was not going to get on the air. Sadly, I never got a radio to Bill he could use before he passed away. The FRG-7 was too complicated and he didn't stay up late enough. I found a 12 V 1 A wall wart, so I thought it made sense. I'm generally used to them being *below* rated output. I'm also used to seeing 176 V on the ground lead on 2 wire mains powered T&M kit from China e.g. the F***Tech FY6800.

There is an old proverb among the Unix greybeards. "Be tolerant of what you accept and strict about what you produce." I see no reason that should not apply to power inputs for QRP kit.

Have Fun!
Reg
Re: ABS for QMX+. Battery/charger design improvements over version 1.1 #PSU #QMXplus #ABS

 

Hi Sardar and All,
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TP4056 is only a charger. using 3 of them can charge but you won¡¯t have balancing which will eventually overcharge cells and damage batteries. These bms boards are pretty good in what they are intended for, balancing, over and under voltage protection and short circuit protection. For charging using a constant current/constant voltage 12.6v supply is the best solution as I pointed out before as ready made wall warts on amazon.
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one more point is that those 3S 40 Amp bms is kinda overkill for the task in hand which is to power QMX+.?

I recently use this BMS for a project which performs similar task in a smaller package with less amp.
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My personal choice is none of these but use an external battery pack which can power all QRPlabs rigs and small enough to carry around.?
I even power my IC-705 with this powerpack.
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It is 23$ which defies the purpose of going through the hassle of creating a Powerpack at this price point.
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Wouldn¡¯t it be simpler and practical to just add the ATU inside the QMX+ and use this powerpack externally to power all? Just a thought.
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--
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73, Barb
Re: ABS for QMX+. Battery/charger design improvements over version 1.1 #PSU #QMXplus #ABS

 

Hi Sardar,
I suspect any solution using switching converters is going to generate RFI.
Anyway, a few thoughts below.
73, Dave
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General
I am not so sure that adding switching regulator devices in the QMX is a good idea from an RFI point of view.
Hans has been able to minimise the RFI issues with the QMX SMPS implementation by adjusting the switching frequency based on the operating frequency of the radio.
If the radio is not used whilst charging it may be acceptable, assuming the switching regulators are not powered when using the radio.
The MAX745 device is effectively the same as a CV/CC buck converter, The additional boost converter is required to satisfy the minimum VIN of the MAX745.
Where VIN (typical) = VBATT(max) + 2V = 12.6 + 2 = 14.6V.
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Separate Connectors
Trying to use the QMX+ DCIN socket for the CHRGIN and DCIN makes things a little awkward in my opinion.
An option could be to have separate connectors for the battery section as per the SOTA PSU, but with it integrated inside the QMX+ enclosure.
This would allow the battery to be charged whilst powering the radio from a separate independent PSU.
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USB-C PD Integrated Powerbank
As others have already commented on the forum, USB-C PD provides an option for powering the QMX.
It may be worthwhile evaluating this as a possible integrated solution.
There are many cost-effective USB-C PD power bank modules available.
Various output power versions are available, ranging from 18W to 65W.
As with all switched mode solutions, the main problem could be RFI, and the powerbank modules use a switcher for both charge/discharge.
The main advantages with USB-C PD:
- Charging of the battery from a standard 5V charger.
- Different output voltages can be used with a suitable USB-C PD trigger cable and/or module.
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Charging:

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Simultaneous Charging and QMX Power:
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Battery Power:

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Example 1 (18W):

Input: 5V, 9V, 12V
Output (PD): ?5V (3.1A), 9V (2.0A), 12V (1.5A)
Cost: ?2

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Example 2 (65W):
Input: (PD) 5V, 9V, 12V, 15V, 20V
Output: ?(PD) 5V (3A), 9V (3A), 12V (3A); (PPS) 3.3V~21V (3A)
Cost: ?10
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Re: ABS for QMX+. Battery/charger design improvements over version 1.1 #PSU #QMXplus #ABS

 

Hi Sardar,
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from my point of view the current solution with the balancer board is good enough. With normal 12V power supply during operation there should be no issue.
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My concern is the life power at the jack, which makes me think that I won't use the battery option.
I don't think that this can be solved with the companion board, as it would require changes on the QMX+ board.
I was thinking about cutting the barrel jack center pin and put a Schottky in-between, but that spot is not really accesible anymore with the fully assembled QMX+.
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73
DK7CVD
Re: 80m QCX mini for sale

 

Is still available I¡¯m keen to use 80m for the first time
73 John M7FZC
Diagnostics fail with no BS170s installed #qmx

 

I've been trying the hardware diagnostics with no BS170s installed and all the Rx tests behave as if there's no test signal input.
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The Receiver is working.? I connected an antenna and can hear and decode FT8 signals.
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I would expect that the receive tests would work, the Audio Filter Sweep, RF Filter Sweep, Image Sweep and Test ADC I/Q.
AIUI none of these use the Tx side, they use a test signal provided by CLK2 injected into the Rx chain through R518 don't they?
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Could CLK2 not be working?
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The MS5351 must be working because Rx works, at least for CLK0 and CLK1.
The voltage on all the BS170 gates goes from 0 to just over 2V when transmitting and the drain pins go to the input voltage. I guess this means that CLK2 is OK and that ICs 501, 502 and 503 are OK.
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Have I missed something?
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Chris, G5CTH
Re: QMX: Low Power & no receive

 

Ja,
So, based on your scans I would immediately suspect the soldering of the T501 transformer, and your LPF toroids. Maybe also the winding of T501.?
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73, Dan - W2DLC
Re: QMX+ becomes a DX magnet with a simple portable antenna

 

I use these:
--
John AE5X
Re: QMX Mid Band RX issue

 

Dear Stan, Please give me some advice.
I tried sequentially inputting signals from 7Mhz to 21Mhz to My QMX using Tiny SA. I was able to receive everything.
So I think replacing PCM1804 should be prioritized rather than rewinding T401 or L401a/b. Is this idea wrong?
I want to minimize damage to the PCB.
Today, I asked a store in Akihabara-town in Japan to order PCM1804. There was no shipping charge, but it was little expensive.
Mitsu JK1PDR
QMX: Low Power & no receive

 

#qmx

Hello all,
Seeking your help with my build here: QXM 80 - 20 version with 12 V

Following problems:
(1) Low power, e.g. on 20 m around 1,0 W. FT8 signal is going out and received.
(2) No reception at all: All bands have no reception and are deaf.

Attached some pictures from the diagnostics.

KIndly give some advice where to check.

Thanks Jan DG1LJP
80m QCX mini for sale

 

80m QCX mini with AGC unit fitted excellent condition. I built this to use in the QRP section of the RSGB club contests where it performed very well, only used a couple of times and never portable...in excellent condition.
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Yours for ?50 plus postage
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73 Steve G4EDG Exeter
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g4edg@...
Re: QMX+ becomes a DX magnet with a simple portable antenna

 

¿ªÔÆÌåÓý

Just put in ¡°flip up feet for laptop¡± in Amazon or other site. ?Many options and I use them on all my QRP radios.

Be the REASON someone smiles today.

Dave K8WPE

On Nov 20, 2024, at 3:55?AM, Crni Mrki, DK4BN via groups.io <crnimrki@...> wrote:

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HI John.
Where can I get the flipup feet you have on your QMX+?

Thank you.
73 DE DK4BN
Re: MFJ-1984LP Antenna 80m-10m EFHW 30W

 

Forgot about this, good call!
Re: QMX+ becomes a DX magnet with a simple portable antenna

 

HI John.
Where can I get the flipup feet you have on your QMX+?

Thank you.
73 DE DK4BN
Re: Speaker for QCX+

 

Re: Automatic Antenna Tuner, Internal Battery with a charger and built-in speaker for QMX+. Open Source.

 

On Tue, Nov 19, 2024 at 10:47 AM, Barry VA7GEM wrote:
There is very cheap way to do this. Pick up some flake Shellac and mix with Alcohol then paint it on.
I just use folded paper towel. After you have painted 5 to 6 times you can just wipe with alcohol between prints.
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Wow--that's one I've not tried yet, Sadar! I've tried? more adhesion promotion candidates than most users though. I like Magigoo--at least the original version I tired, but I really like how one version of Vision Miner Nano Polymer Adhesive works with just about all FDM polymer materials. The only two materials that Vision Miner says don't work are POM and PP. I've never printed POM and I have another adhesive for PP that's sold by the PP filament manufacturer.
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I was experimenting with ATU EEPROM cell codes today. Don't make the mistake of, thinking it's a PIC, accidentally plugging an ATMega chip into a PICit3 and trying to program it with your Arduino sketch! (My aging eyes make this kind of error increasingly likely.)? The ATU will still work---a little, but the communications between PIC and ATMega are obviously borked, due to some kind of ATmega I/O port damage. I tried reprogramming the damage ATmega to no avail. A programmed new one fix the ATU though! Things could have been worse. I could've damaged my PICkit 3 instead of just a $2.88 ATMega chip!
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73,
Cal (AD8Q)
troubleshoot QMX+. just blocks on the display.

 

I just tried to download the firmware. ?The display is just a row of blocks. ?And when I clicked and dragged the file into E:QMX. it appeared to download. ?But nothing doing with turning rig on and off. ?I think all the parts are in the right place. ?Any suggestions where to start. ? I will resolder that horrible row of 16 pins again. ?Thanks.
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I did replace the variable resister that changes the brightness as I accidentally touched the original one with the iron and pooched it. ?The resister does make it lighter and darker blocks. ?yeah.
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Re: Speaker for QCX+

 

Has anyone used a speaker from a smart phone for any electronic projects?
Examples
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Thanks
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George
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