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

 

You can even attach the 3000mA 12 V Talentcell to the top of the QMX+ enclosure (or bottom if you are using flip up front feet))? with double sided tape and use a small cable between the two power connectors.
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73 Kees K5BCQ
Re: Wall warts can be fatal to QMX :-(

 

The LM2940CT-12 seems to work fine on my 12v rig.
Could be some QMX's built for 9v may want more than 1 Amp.
The LM2940CT-12 is around a dollar for one piece, higher currents cost more.
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Here's a selection of 9 and 12 Volt low dropout linear regulators in the TO220 package
that are good for 1.5 and 2 Amps.? If Hans wishes to keep cost of a kit to a minimum,
he could lay the board out for a TO220 and have cheapskate builders jump it with a wire.
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Jerry, KE7ER
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On Wed, Nov 20, 2024 at 07:05 AM, Jerry Gaffke wrote:

Next board rev of the QMX
should be laid out for an LM2940CT-12. or LM2940CT-9.0 (have a dropout voltage of 0.5v at 1a).
Re: ABS for QMX+. Battery/charger design improvements over version 1.1 #PSU #QMXplus #ABS

 

Dave,
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These relatively smaller modules all use a common battery charge/battery protection controller IC:
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This is the datasheet of that IC.
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73, Barb
Re: Wall warts can be fatal to QMX :-(

 

Did a quick search, seems the spelling is best made a little different:
A ¡°ditty bopper¡± was a slang term for a Morse code intercept operator, MOS 05H in the Army. Most were assigned to the ASA (Army Security Agency)?...
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Good of you to try to help your friend like that, give him something to do other than stare at the wall all day.
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I agree that power requirements into our gear should not be so fussy.? Next board rev of the QMX
should be laid out for an LM2940CT-12. or LM2940CT-9.0 (have a dropout voltage of 0.5v at 1a).
For now, easy enough to add one as a lump in your power supply cable,
include the caps suggested in the datasheet.
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Jerry, KE7ER
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On Wed, Nov 20, 2024 at 05:49 AM, Reginald Beardsley wrote:

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

 

Hi Cal,
I would like to add my 2 cents with regard to your purchases so far. ?It would make sense to me if all the parts you have purchased so far-to get to where you need to be with this project- be rolled into the price per unit for those initially interested. ?Sorry for the run-on sentence.
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Taking that cost and sharing it among 25 or more early adopters shouldn¡¯t be a deal breaker for those of us realizing the value of this accessory.
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73,
Chris
W3PB
Re: QMX+ becomes a DX magnet with a simple portable antenna

 

On Wed, Nov 20, 2024 at 04:32 AM, John AE5X wrote:
I use these:
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John AE5X
very reasonable at $8.99
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I switched to Amazon Canada to find surprise $38.37
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Re: Diagnostics fail with no BS170s installed #qmx

 

I've borrowed a signal analyser and what this shows me on the antenna on the 20m band in the diagnostics mode is a signal at 14.061 Mhz when receiving and 14.077 when transmitting.? I suppose the 14.061 signal is CLK0 and CLK1 driving the Tayloe detector and the 14.077 signal is CLK2 trying to drive the missing PA.? The 14.061 is at -63 dBm and the 14.077 signal at -82 dBm.
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I noticed that in normal digi mode setting 14.074.00 showed the detect signal at 14.062003? but changing the frequency in steps of 10 or 100Hz gave strange results, with the detector clock not changing as expected, however listening I can hear the demodulated frequency changing.? I suppose there's some clever adjustments going on in software.
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Chris
Re: ABS for QMX+. Battery/charger design improvements over version 1.1 #PSU #QMXplus #ABS

 

Hi Barb,
I agree, the high power BMS is an overkill. The lower power versions don¡¯t have any balance circuitry for whatever reason.
Keeping things simple is probably a good idea.
I guess it¡¯s all down to use case and personal preference.
73, Dave
Re: QMX+ becomes a DX magnet with a simple portable antenna

 

David,
These work great too!
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Rick K8BMA?
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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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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:
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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
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