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Low and High Band QDX for Sale

 

¿ªÔÆÌåÓý

? I have a Low Band and a High Band QDX I would like to sell. Both were tested on 9 volts and a Lipo Battery, 13.3 volts into a dummy load and tested on an antenna for spots. I have only used these as WSPR Beacons. My station is powered from solar panels and I use a 9 volt DC to DC converter to power the units, they were built for 12 volts.

???? Low Band QDX was purchased on the net and built by the seller, I did have to replace the finals due an antenna issue, I used devices purchased from Mouser, PC Board is Rev 4. Power out at 9 volts is 3 to 2.7 watts, at 13.3 volts power out is 5 to 6 watts. It has always worked fine.

???? High Band QDX was built by QRPLabs, PC Board is Rev 5. Power out at 9 volts is 1.6 to 2 watts and at 13.3 volts 2.9 to 3.5 watts.

???? Will sell both for $120 shipped or individually for $60 each shipped, Paypal is fine. Any questions contact me off line at my email, thanks!!


???????????????????????????????????????? W6TOM
ABS for QMX+. Battery/charger design improvements over version 1.1 #PSU #QMXplus #ABS

 

Cal, Stan,
?
Could you draft your schematics on a piece of a napkin and submit a photo? I am not sure I am visualizing your ideas over the messages?
?
--
73,
Sardar (AC8L, 4K6SA, VA3DUA).
Re: Automatic Antenna Tuner, Internal Battery with a charger and built-in speaker for QMX+. Open Source.

 

On Mon, Nov 18, 2024 at 01:03 PM, Cal (AD8Q) wrote:
this design needs to be frozen
To me - version 1 design is frozen :) Unless catastrophic discoveries are made with new PCB's that less likely :)
?
However, we should continue improvement discussions - that is the sweatiest part of this unexpected engagement I found here.
To make this more formal - I can suggest we move improvement discussions to anew thread (I can initiate that). And keep current threat solely for the "sales, marketing (and finance)" topic related to a group buy.
?
Hope everybody agrees?
?
--
73,
Sardar (AC8L, 4K6SA, VA3DUA).
Re: QMX mid band 60m tuning problem

 

Hi,

Set "Band limits" to "None".? P.51 of the operation manual v.26 refers.

Regards, Jonas


Den m?n 18 nov. 2024 kl 19:21 skrev Zrinko Ivan Vukoja via <ivan.9a5czi=[email protected]>:

My new QMX has a strange tuning problem on 60m only. It is not encoder problem. Tuning has pattern that it follows and it is repeatable.
You could see it on this short video:
?
?
This QMX has also problem with image rejection and I found it is connected with PCM1804 (input signals at PCM1804 have correct amplitude and phase).
Is it possible that the two problems are related.
?
73 de Zrinko Ivan, 9A7AM
QMX mid band 60m tuning problem

 

My new QMX has a strange tuning problem on 60m only. It is not encoder problem. Tuning has pattern that it follows and it is repeatable.
You could see it on this short video:
?
?
This QMX has also problem with image rejection and I found it is connected with PCM1804 (input signals at PCM1804 have correct amplitude and phase).
Is it possible that the two problems are related.
?
73 de Zrinko Ivan, 9A7AM
Re: Automatic Antenna Tuner, Internal Battery with a charger and built-in speaker for QMX+. Open Source.

 

On Mon, Nov 18, 2024 at 10:03 AM, Cal (AD8Q) wrote:
It turns the BMS into a suitable Li-ion charger and blocks the possibility of reverse current too.
Quoting myself (again)...and hopefully more accurately asserting: The BMS is not a charger. The Drok regulator AND a suitable power source provide the missing charger functionality, as might the target of Barbs links earlier in this thread, which Sardar mentioned, at a lower price.
?
73, Cal
Re: Automatic Antenna Tuner, Internal Battery with a charger and built-in speaker for QMX+. Open Source.

 

On Mon, Nov 18, 2024 at 10:03 AM, Cal (AD8Q) wrote:
this design needs to be frozen
I completely agree, Cal.? Thank you for the great work you are doing.
Stan
Re: Automatic Antenna Tuner, Internal Battery with a charger and built-in speaker for QMX+. Open Source.

 

On Mon, Nov 18, 2024 at 09:28 AM, Stan Dye wrote:
Some users may not want to make that mod (cutting the center pin from the main board), but it would work to make the design 'safer' and not subject to the discharge Dirk is experiencing.? I guess the jumper wire connector (instead of being a 2mm banana) could be one that would mate with the JP101 pin 1 connector post, such that connecting them would enable QMX use when the companion board is removed.
Stan,
?
RR--I'm not going to cut the center pin from MY main board! I'm quite happy with my power cord inline Drok adjustable regulator solution to these problems. With the correct settings on the V and I adjuster pots, I get the CC bulk phase to 12.6V at whatever current I set (I like 500mA), then the 12.6V is held and the current tapers. It turns the BMS into a suitable Li-ion charger and blocks the possibility of reverse current too.
?
As the manager of the group purchase of PCBs, I need to state here and now that this design needs to be frozen for awhile, unless there is a very good reason for a change (and when the Drok regulator seems to me to be a good solution here, board changes don't seem to be necessary). The Drok provides maximum convenience and custom charge profile preferences too.
?
I worry that I will perpetually be out of pocket for purchasing 5-pack minimums of quickly obsoleted PCBs. In good conscience, I can only amortize scrap material between all the buyers for so much and so long!
?
Now I'm sounding like the sales and marketing (and finance) folks where I used to work! ;)
?
73,
Cal (AD8Q)
Re: Automatic Antenna Tuner, Internal Battery with a charger and built-in speaker for QMX+. Open Source.

 

On Mon, Nov 18, 2024 at 07:02 AM, <me@...> wrote:
The battery voltage is directly applied to the connector.
Another solution that we could consider is to put a suitable diode on the companion board, feeding into the + terminal of the BMS.? The other end of that diode gets hooked (using an 18 guage or so jumper wire) to the center pin of the DC in jack, which we cut away from the main board.? That way, the power in connector is protected from the back emf, and will charge the batteries fine, with the voltage to the main board now always coming via the companion board.? This diode could be dead-bugged on to the existing companion board, or it would be a simple add to the board layout which could optionally be installed. Probably use something like one of those 2mm banana jacks to connect the jumper to enable removing the boards.
?
Some users may not want to make that mod (cutting the center pin from the main board), but it would work to make the design 'safer' and not subject to the discharge Dirk is experiencing.? I guess the jumper wire connector (instead of being a 2mm banana) could be one that would mate with the JP101 pin 1 connector post, such that connecting them would enable QMX use when the companion board is removed.
QMX hardware test behavior in practice mode

 

While building and debugging my QMX (1_00_027 firmware) I had a confusing moment when I put the transceiver into Practice mode, forgot about it, and then tried to use the SWR Measurement function.? Of course, while in Practice mode, no power was coming out and so I was befuddled at the SWR readings bouncing between 1.4-2.1, even with a dummy load.? I went so far as to check the output power externally and got nothing, as you would expect while the transmitter is disabled.
?
In my confusion, I thought I had blown out the BS170s.? I had the unit disassembled and was ready to replace the transistors before I tried once more to measure the power while transmitting with a straight key.? This is when I noticed the P on the display and remembered that I was in Practice mode.?
?
I think it would be helpful to have a warning displayed on some of the hardware tests that will still try and give a result when in Practice mode.? Alternately, it would be even more convenient to provide the option of disabling Practice mode along with the warning.? Either way, it may save someone the trouble of replacing components and potentially damaging the PCB.
?
Loving the kit and excited about the SSB update!
?
John VA7JBE
Re: Automatic Antenna Tuner, Internal Battery with a charger and built-in speaker for QMX+. Open Source.

 

On Mon, Nov 11, 2024 at 10:37 AM, <me@...> wrote:
After you finish adding connectors to QMX+ main PCB - can you take photo (same as I did for instructions) and send me? I will update the PDF. Then we do not need a red X :)
I have only one QMX+.
?
Sorry that I forgot to take the photo last time, Sardar. I'll do it next time!
?
73,
Cal (AD8Q)
Re: Automatic Antenna Tuner, Internal Battery with a charger and built-in speaker for QMX+. Open Source.

 

On Mon, Nov 18, 2024 at 06:11 AM, Dirk wrote:
The batteries are now charging in the QMX+.
With 12.5V supply the current is about 1.2 A, with empty batteries this would be higher.
On Mon, Nov 18, 2024 at 07:02 AM, <me@...> wrote:
3. If we worry about exceeding 12V while charging - we can keep QMX+ off during charging cycle or in RX mode only.
After burning my short 0.5mm trace with too much current from the high charge voltage I was using, I replaced the trace with a 28 AWG wire and successfully and more competently manually managed the output voltage from my Alinco power supply when charging the QMX+ABS. By keeping the QMX+ powered off or in receive-only when voltages required for continued charging exceed more than than 12V, I have experienced no problems since.
?
It's not convenient to need to keep adjusting the Alinco output voltage knob. Other loads sometimes powered by the Alinco (rigs and ATUs) receive the reduced voltage too so I installed a Drok buck/boost converter with adjustable output current limiting on the charge cable to my QMX+ABS. It is working great! I usually set it for 500mA max output and a max voltage of 12.6V. I used a QRP-Labs dummy load to make sure I got it set about right at first (252mA is output into 50Ohms at? 12.6V) before connecting it to the QMX+ABS.
?
The Drok's "Output anti-backflow" feature seems to function. I can turn off the Alinco with no ill effects. Here's YAAL (Yet Another Amazon Link) for y'al. I'm using the buck/boost version but the others should work with an appropriate power source :
?
As always with these things, everyone else's mileage may vary!
?
73,
Cal (AD8Q)
Re: MFJ-1984LP Antenna 80m-10m EFHW 30W

 

First I messed up my antenna is:

MFJ-1982LP, END FED, 1/2 WAVE, 80-10M, 30W WIRE ANTENNA

Not MFJ-1984LP.

The coil has 6 turns.

Thanks,

AC4OW, Sam

Thanks,

Sam Hanie


623-219-8130


On Mon, Nov 18, 2024 at 6:41?AM w0wly via <w0wly=[email protected]> wrote:
Good day
?
?the setup I¡¯ve seen has the coil about 6ft from the transformer. 6-7 turns on 1 inch form.? This should pull upper bands down into CW portions nicely.?

take a look at the ¡°my antennas ¡° brand of EFHW available I believe they show this. There are also some YouTube videos by an N4 call that shows how to do the coil.?

several others for sure. I guess it originally came from a German antenna book?? Not sure on that. But it works!? Good luck. Sorry I don¡¯t have more specifics. I¡¯m on the move but figured I¡¯d send along what I could remember. I¡¯m sure someone will be along who will fill in more blanks or correct me :).?
Re: QMX+: RWTST how to wind T501

 

If it is symmetrical still I don't get where the 3:2 ratio is created, could someone please shed some light?
The 3:2 transformer has two symmetrical windings.
One, the primary has 3 turns, the other 2 turns.
Re: Automatic Antenna Tuner, Internal Battery with a charger and built-in speaker for QMX+. Open Source.

 

With LM386 instability (which I have run into over the years), the series RC has to be matched to the speaker of interest.? Some standard values such as 10 ohms and 0.05uF as indicated in the data sheet generally work for many speakers but not always.? They are a function of gain set in the LM386 and the actual speaker driver used. The series RC is known as a Buchorot Cell which is a subset of a Zobel network.?


The R value should be equal to the speaker driver's resistance at DC and the C should be equal to L/(R squared) where L is the speaker driver's equivalent inductance in a simplified speaker driver model of a series R-L.?

I didn't know any of this as a teenager and got frustrated with oscillating LM386's thinking is a poor chip.? I got wiser after I got my EE degree.

-Steve K1RF




------ Original Message ------
From "Dave (G8PTN) via groups.io" <daveg8ptn@...>
Date 11/16/2024 5:40:18 AM
Subject Re: [QRPLabs] Automatic Antenna Tuner, Internal Battery with a charger and built-in speaker for QMX+. Open Source.

Hi Cal,
A few comments below.
73, Dave
?
My 18650 cells were only charged to about 3.8V so I decided to try charging with with the radio off. I set my trusty Alinco supply for ~13.5V and plugged connected to my QMX+ABS. A couple of hours later I checked and there's no QMX+ power-up. Investigation revealed a blown trace. It's the short trace from the (-) pad on the U7 battery holder and the via that connects to the short trace on the other side to the BMS 0V pad.
?
The chances are with the 13.5V power supply (without current limiting), there would have been a lot of current going through the traces.
When the batteries are at a low voltage, it is important to have a power source (charger) with a constant current mode.
The maximum charge voltage should be no more than 12.6V during the constant voltage phase.
?
?
On the 18650 cells, I am not sure if the "P" means protected. These cells have an internal protection circuit and tend to be physically longer.
In this companion board case, protected cells are not required, the BMS does this.
?
On the audio amplifier, the LM386 can sometimes be a bit problematic in terms of instability issues. I am not too sure what the intended characteristics are meant to be with the circuit.
Hopefully, Dirk can do some further checking with the oscilloscope.
?

?
?
Re: QMX+: RWTST how to wind T501

 

You are correct in your statements regarding the photos.? It is symmetrical.
The 3:2 comes in the following steps, when you cut the twisted loop (becomes the two ends of the primary), and re-twist the correct two of the other leads to become the center-tap of the primary.
Re: Automatic Antenna Tuner, Internal Battery with a charger and built-in speaker for QMX+. Open Source.

 

Hi Sardar,
?
please don't get my above comment wrong. I fully agree with you, it's a low cost, low effort solution, which can work for most cases.
I just wanted to mention that this is not a "consumer proof" solution. Okay, as licensed amateur radio operator you should know what you're doing.
My Agilent bench power supply is not suited for this application. As soon as I switch the output off, it drains the battery.
?
Anyhow, I think such a discaimer on the GitHub would be a good idea.
Re: Brand Reccomendation for 28AWG wire?

 

Transformers from old wall power bricks have good wire in them a lot of times.?
--
73, Dan - W2DLC
Re: Brand Reccomendation for 28AWG wire?

 

Great save.?

You have nice tight winds on that transformer.
Perhaps a bit more than the recommended 3 per centimeter being enough.?

I too snapped a wire on that assembly on my first QMX build. I did have a tighter twist ratio than the recommended amount. BUT, I had checked and smoothed as necessary the toroids edges because Hans had included that suggestion in the QMX instructions.
(Though I don't see that specific guideline in the QMX+ assembly manual.)

But my snap occured when unwinding the twists, and spreading? the ends for ID'ing and aligning the ABC pairs.?

I rewound mine with less twists and decided to GENTLY press out the curled twists in each leg with a small pair of flat faced needle noses pliers. That was before moving on for ID'ing, stripping enamel and aligning the pair order for insertion.?

That technique worked for the retry.? And on two additional QMX+ builds and on my new QDX LB.

GREG KI4NVX?


On Mon, Nov 18, 2024 at 1:09 AM, Carol KP4MD
<kp4md@...> wrote:
I strongly suggest, Hans, that you please add a warning in your assembly manuals for builders to deburr their ferrite cores.?
I neglected to do and also snapped a wire off T401, never before having seen ferrites with such sharp edges.?
As I spread the leads of the trifilar T401 toroid to mount it on the board, one of its leads broke off where a sharp edge on the ferrite had nicked it.?
I was lucky to successfully splice back the broken lead with solder and to secure it with a hemostat while soldering T401 onto the board.?
The manual and support are otherwise excellent.? This was my only mishap while building the QMX+.?
The radio lit up without a puff of smoke and is now on the air!

?
?
?
?
Re: QMX+: RWTST how to wind T501

 

It's symmetrical.
?
On Mon, Nov 18, 2024 at 05:40 AM, Giuseppe Marullo[iw2jww] wrote:

I don't understand if steps 11 and 12 are producing a "symmetrical" result.
I m winding and everything is fine until step 10 included.
Figure on step 11 seems to be as step 11 is already executed and half way to what is expected in step 12.
Figure on step 12 shows what it should be after step 12 execution.

Is okay to consider step 11 and 12 producing a symmetrical winding? Or one twisted wire should pass once more compared to the other?

If it is symmetrical still I don't get where the 3:2 ratio is created, could someone please shed some light?
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