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Re: RF Amp using the now cheap GaN-FET's

 

For class D or E gan and SiC are high performing.
?
BUT... you have to do polar (QMX) to get to SSB or?
like a bunch around here AM.
?
Turns out AM is easy, A PWM modulator driving class E or D
output stage.? Most use class E and output power of 385W
carrier for 1500W PEP at 100% modulated.? Impressive
very high quality signals .
?
A push pull class D? would be interesting but the amplitude
modulator has to be equally robust and efficient (PWM).
?
Work I did, efficiencies or 96% were done and better is
possible.? ?At low power the MPU and other supporting
circuits? contribute to power used and not directly to
RF out.? But 50-60% DC in to RF out is easy.?
?
Compare that to IC7300 TX at 22A @13V (280W) for 100w out.
Dial it back to 20W out and you are still pulling about 7A or 91W.
Its not that the finals are inefficient but you have drivers,
DSP, display, and so on all using power.
?
?
It would be attention grabbing.
?
--
Allison
------------------
Post online only,?
direct email will go to the bit bucket.
Re: QMX Plus in contest

 

Jerry,
?
I used a QMX+ as well in the WPX contest, which yielded 560 Q's working search and pounce; 5W into a 2 x 16m doublet up 11m.
?
I have fitted a small board with an electronic T/R switch inside the case, that feeds a RSP1A SDR, controlled by N1MM's Spectrum Window feature.
This is mandatory for working S&P with 5W as the spectrum window shows how strong a paticular station is coming in, enhancing the chance he will hear you.
?
Martin, I do not have the CW filter issue, but I am using as speaker a CW GUN, tuned to 700 Hz, which provides extra filtering, which might cover this issue up.
I noted some issues on 40M as well and will look into that. If it is really due to overload, I will build an attenuator with an electronic by-pass switch, controlled by PTT.
?
Why? Because the QSK of the QMX+ is awesome and helps to win in a small pileup competing with much stronger stations.
Turn around time is very short and I am? heard often before anyone else has started yet, resulting in? .--.? .-? ..--..?
The QSK is just as good as in my RGO-ONE, which also features electronic switching only.
?
Regarding high end radios, I sold my FTDX3000, which has very good filtering and noise reduction, yet suffers from listening fatigue and due to using relays has less than optimum QSK.
I have now three (QRP) contest radio's: the RGO-ONE, QMX+ and Elecraft K2, though the latter's QSK leaves a bit to be desired. The audio from all three radio's is excellent.
?
My fasted rate in S&P mode was 40 per hour.?
?
73,
Roelof, pa0rdt
?
?
Re: QMX+ SSB audio distorted on one band only

 

Thanks Stan.
?
I tried lots of different numerical values in the band configuration for 20m and couldn't get the phase calibration to start. I also tried wiggling the supply voltage a few tenths either side of 12v but still couldn't get the calibration to start.
?
I guess I'll just have to accept the default value for 20m SSB.
?
73, Colin
Re: 3 cell lipo battery, how to use it anyway

 

Bruce,
?
>>All I would add is that the 'charge to 3.85V' approach is fine short term if they get fully charged every few uses /? few times a year.
?
Lipo its 4.2 max,? 3.85 would be fine for use but capacity is in the 40-60% region.
? However the lifespan (in charge cycles) it would be very good.
? That voltage would be excellent for storing the cells.
? There is no requirement for full charge save for if you want full capacity for use.
?
LFP-LiFePO4 that too much as typical for them 3.65V.
?
LFP are a better match to common 12V system being closer to the
nominal? 13.8V (14.6 full charge, 12V cutoff).? ? ?They hold a narrower
voltage range in use.?
?
?
--
Allison
------------------
Post online only, direct email is filter to the bit bucket.
Re: Elecraft T-1 tuner usage

 

¿ªÔÆÌåÓý

Look at the T1 manual on the Elecraft website. ?It explains the remote control of the T1?
Milt w8nue

On May 26, 2025, at 11:22?AM, Braden Glett via groups.io <bradenglett@...> wrote:

?
Could someone please explain to me a simple, quick,? non-fiddly way to send a signal that my T-1 tuner can use to tune itself? I tried searching the forums but didn't find anything. Thanks all.?
Re: QMX Plus in contest

 

No Jerry I don't want to compare and I don't want all these features. Just I think a radio licke the QCX+ should be able to handle signals from a decent antenna better.? I am sure Hans has a good list of to do's and will get things done.
--
Martin
DK3UW
Re: QMX Plus in contest

 

Accessories are TOP
--
Martin
DK3UW

QMX-DK3UW.jpg

Elecraft T-1 tuner usage

 

Could someone please explain to me a simple, quick,? non-fiddly way to send a signal that my T-1 tuner can use to tune itself? I tried searching the forums but didn't find anything. Thanks all.?
Re: QCX Challenge

 

I honestly sat in the car from 12 to 14 Z on the beach cqing on 20m, didn't hear participants, made 2 POTA/SOTA 2way qrp contacts instead.
73
Igor, oh2jxa
Timing confusion U3S #gps #u3s #wspr

 

I have run my U3S many times before and it has run flawlessly with either a Beitian E-280 or Acxico GPS module attached.? Both are U-blox M8 series.
It has been sitting for some time, but I have a new propagation test and pulled it out to set it up again.
The unit has the 25MHz TCXO module installed.
The heart pumps on the screen, and the Time display is dead on when watching WSJT-X on my computer or a GPS clock screen from a GPS connected to the computer.
?
?
Now it is acting rather strange.
The old setup was 2-minutes WSPR TX, 2 minutes WSPR RX on each of 5 bands (10, 12, 15, 18, and 20m) with a Frame 30, so time between.
The first TX decodes in WSJT, but each TX after that is late (later with each TX).? By the 3rd TX (15m) it starts 10 seconds late and is not decoded at all.
After each CAL sequence the display shows '=' and makes no changes.? CAL (Step Time) is 01 100.
?
I removed the RX windows and cut it to the 3 main bands (10m, 15m, and 20m) and the Frame to 10.?? Short_Setup.txt attached.
The first TX decodes in WSJT, but each TX after that is late (later with each TX).? The second TX (15m now) doesn't decode, and the 3rd TX (20m) starts 10 seconds late.
Round it goes, and the first TX is right on time again!
?
-------
Robert Giuliano
KB8RCO

Short_Setup.txt
Short_Setup.txt

Re: QMX Plus in contest

 

You do give good information about some possible firmware changes to the QMX.
However, you're comparing the QMX to a rig that costs 15 times as much.
One would hope the Flex 1500 might be a little bit better in some respects.
?
Jerry, KE7ER

?
On Mon, May 26, 2025 at 07:23 AM, Martin DK3UW wrote:

Hi all,
?
someone stated elsewhere, that the QMX+ was a good rig for contest. Not really I think. I just used it in the CQWPX as well as my Flex 1500. Well the waterfall is a + for the flex ( I dont want tb buy? more hardware to have one for the QMX) and changing the filters directly on the Hercules console is way quicker. I have not updated to the SSB software yet. The 300 hz filter is vy wide on the high side. Strong signals can be heard widely. Nothing after 0 beat.? Also strong signals seem to saturate the rx and that was a problem especially on 40 m? CW clicks are not nice but that is known. 160 m when the band is used above 1.840 is not workable as all stn from below have a similar signal there again. And then I have still to figure out how to set up the AGC. The hang time on strong signals is too long and that makes life difficult. On the positive side I prefer the audio sound of the QMX+ to the flex.
?
I dont't want to be too critical and I never had a newer state of the art rig to compare.? Years back I had a TS 830 and liked that.? S next up is the region 1 FD for the QMX+
--
Martin
DK3UW
Re: 3 cell lipo battery, how to use it anyway

 

Bruce,
?
When you say "charge to 3.85V", I assume that's a typo for 3.65v and that we are talking about the LiFePO4 chemistry.
Charging LiFePO4 cells to 3.65V should be fine whether short term or long term.
Once fully charged, the charger should either be disconnected or the charge voltage should be backed off to perhaps 3.4V to avoid overcharging.
If there is a BMS involved, it should include that functionality.
But know that the BMS will continuously draw current, and eventually run down the battery and perhaps ruin it.
The self discharge rate of a raw cell is generally quite a bit less.
?
Discussion so far has been mostly about raw single cells, no protection or BMS involved.
Here's an example of a large raw prisimatic LiFePO4 cell:
They have plenty of other choices: ??
$83 for a 304AH cell with free shipping within the US is still a good deal inspite of the current mess with tarrifs on Chinese goods.
That says something about their costs to manufacture these things.
?
On a lead acid 12v battery with 6 cells of 2v each, if one of the cells reaches full charge first we can continue to supply
charging current and the excess energy will get boiled off by that high cell outgassing hydrogen and oxygen from
breaking down water.? In the case of all the lithium chemistries, overcharging a cell will instead just destroy the cell.
This is why a lithium battery requires a fancy BMS but a lead acid battery does not.
?
What a BMS might do varies as you suggest, generally it is responsible for keeping a series string of cells?
at roughly the same state of charge.? It? may do this by burning up some of the charge in the highest?
voltage cells through a resistor, a more sophisticated BMS can transfer charge from the highest voltage cell
in the series to the lowest. A BMS should also disconnect the battery if an excessively high or low charge state
is detected in any of the cells, or if the load draws too much current.?
Here's an example of a LiFePO4 battery with a BMS inside:
The post says it has a "100A BMS", so if you draw much more than 100A the BMS should disconnect the battery.
This is done through an nFET switch inside the battery, so even if a dodgy BMS fails to disconnect,
the nFET will likely blow with the excessive current.? At 100A max it won't be much good for starting your car,
but it is safer than a lead acid battery which may give several thousand Amps when shorted.
?
You are correct that it is best to occasionally charge a string of lithium cells to something close to a full charge so the BMS
can balance the cells.? I found that when I set the BMS on my off grid system to only start balancing those LiFePO4 cells
at 3.42 Volts,? anything less and it would draw balance current from the wrong cells, perhaps due to slightly different
chemistry between cells.? You are correct that if I only partially charge my battery, I may never have one of those cells
reach 3.42 Volts and the battery would never get balanced, but that may not matter much since I am clearly not trying to use
the full capacity of the battery.? If the cells do not get balanced the BMS is still there to disconnect the charger if
a cell voltage rises above 3.65v or falls below perhaps 2.6v.
?
The common 18650 LiPo cells can be either a raw cell or can include a protection circuit tacked on to the end.
The protection circuit is a very small BMS, protecting the cell from over-charge, over-discharge, and excessive current.
Maximum charge voltage can vary, read the datasheet.
The protection circuit makes the cell a little bit longer, so such a cell may not fit in some battery holders.
If you have a string of 18650 cells, you probably want a separate BMS to keep them balanced even if each
cell includes internal protection, otherwise you won't have the full capacity of the battery available.
The internal protection circuit only knows the voltage of that cell, not the voltage of all other cells in the string.
Operation without a BMS is possible however, in my experience a set of matched 18650's that start out all?
fully charged can remain pretty well balanced for months or even years of use.
?
Jerry, KE7ER
?
?
On Mon, May 26, 2025 at 05:15 AM, Bruce Akhurst wrote:

Good conversation.? ? ?

All I would add is that the 'charge to 3.85V' approach is fine short term if they get fully charged every few uses /? few times a year.

Reason is that increasingly lithium batteries come with internal cell voltage balancing systems.? ?Systems vary but a very common system comes into action (only) once the first cell approaches? 'full' and part-bypasses it so that the other cells can catch up etc before charge cut off.? Over time this gets imbalanced cells back in line (often after two or three full charge cycles)?

Part charging means this probably won't ever happen, so the cells drift out of balance over time and the available capacity of the pack drops.? ? At some point the? BMS may turn the system off due to imbalance.??

LFP batteries are a better match to 12V systems than Lithium or LiPo but in each case a higher voltage source (e.g. 18V power tool battery) and buck converter is an alternative very stable voltage approach?
QCX Challenge

 

?
13:00 session only Jorma OH8TX remembered the date without announcement. Lets hope others will have time for 19:00
?
Martin
DK3UW
QMX Plus in contest

 

Hi all,
?
someone stated elsewhere, that the QMX+ was a good rig for contest. Not really I think. I just used it in the CQWPX as well as my Flex 1500. Well the waterfall is a + for the flex ( I dont want tb buy? more hardware to have one for the QMX) and changing the filters directly on the Hercules console is way quicker. I have not updated to the SSB software yet. The 300 hz filter is vy wide on the high side. Strong signals can be heard widely. Nothing after 0 beat.? Also strong signals seem to saturate the rx and that was a problem especially on 40 m? CW clicks are not nice but that is known. 160 m when the band is used above 1.840 is not workable as all stn from below have a similar signal there again. And then I have still to figure out how to set up the AGC. The hang time on strong signals is too long and that makes life difficult. On the positive side I prefer the audio sound of the QMX+ to the flex.
?
I dont't want to be too critical and I never had a newer state of the art rig to compare.? Years back I had a TS 830 and liked that.? S next up is the region 1 FD for the QMX+
--
Martin
DK3UW
Re: Release of version 2.0 of ABS solution for QMX+ (Automatic internal antenna tuner, internal battery and internal speaker with audio amp) #PSU #QMXplus #audio #ABS #ATU

 

Hi - Wow! Thanks for your hard work. ?This looks like a worthy addition to my QMX+. ?Please add me to the second group buy of this new kit, if there is one!?
73
Bob
WA2I
Re: High current draw on initial power up #qmx #troubleshooting

 

Hi Stan,

Had access to a current limiting supply this moment and I took the chance to run the functional tests on the power supply board, as well as flashing firmware like you suggested to access the diagnostics menu, and I come back with good news and incredibly perplexing news

Good news the first: The LCD backlight wasn't coming on, so it was never in the realm of complete dark magic. I took a picture but I'm not sure how relevant it'll be cause of what happens next

Good news the next: Power supply tests looked good to me
1.1 vcc and +12v were 0-0.1V to gnd
2.1 +12 at 5V, vcc at 0
3.1 +12 at 5v vcc 0.2-0.8v
3.2 pwr_on 3v
4.1 vcc 5v
4.2 ADC_5v 2.5V

With the current always below measurable levels on the benchtop supply I was using, since I never tried to load the board


Perplexing news: After I flashed firmware the problem seems to have gone away? While in bootloader the device was sitting at 250mA current limiting to 6V. As soon as it rebooted into the firmware, current draw plummeted to ~10mA at 10V. Once all the initialization was done and the backlight was active, current stayed ~100mA at 10V. I took the chance to test everything except connecting a paddle, and besides an intermittent ground short on the left encoder button (Which I'll be looking into. Would appreciate suggestions as to how to mitigate that) everything looked good
?
?
I'm still a little apprehensive about actually using this off a battery, just because we never figured out what was causing that behaviour, but with the firmware flashed it hasn't hit the current limit at all.

Thanks for your help through this, VA3KBY
Updated Wiki Page: QMX QMX_plus Debugging #wiki-notice

Group Notification
 

The wiki page QMX QMX_plus Debugging has been updated by @Ludwig_DH8WN <DH8WN@...>.

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Re: QMX SWR measurement is not correct while using with PA

 

Thank you Jerry! I've managed to add proper capacitor at the input of PA (parallel to the secondary winding of the input transformer) and reduce the SWR from 1.9 to 1.1-1.3. It is for 20 m and 15 m bands. For 40 m SWR is still around 1.8 (it was 2.6 before). I used trial and error just testing different ones until it worked.
Re: 3 cell lipo battery, how to use it anyway

 

Good conversation.? ? ?

All I would add is that the 'charge to 3.85V' approach is fine short term if they get fully charged every few uses /? few times a year.

Reason is that increasingly lithium batteries come with internal cell voltage balancing systems.? ?Systems vary but a very common system comes into action (only) once the first cell approaches? 'full' and part-bypasses it so that the other cells can catch up etc before charge cut off.? Over time this gets imbalanced cells back in line (often after two or three full charge cycles)?

Part charging means this probably won't ever happen, so the cells drift out of balance over time and the available capacity of the pack drops.? ? At some point the? BMS may turn the system off due to imbalance.??

LFP batteries are a better match to 12V systems than Lithium or LiPo but in each case a higher voltage source (e.g. 18V power tool battery) and buck converter is an alternative very stable voltage approach?
Re: Release of version 2.0 of ABS solution for QMX+ (Automatic internal antenna tuner, internal battery and internal speaker with audio amp) #PSU #QMXplus #audio #ABS #ATU

 

Likewise for a US group buy. Thanks? Dean N2TNN
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