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Re: QDX: low power on all bands but 80m after PA died

 

Hello!
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Quite some time later... I've also noticed the same, however I can also see that it will short-circuit on all bands but 80m. I have replaced the MOSFETs with the but I also see that IC5 is getting really hot. Thanks to your reply I will try this as well.
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73 de Annard PB5A
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Re: 3 cell lipo battery, how to use it anyway

 

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OK first are we talking about LiPO4 or LiFePo4? very different cells.
Always be sure!
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Lipo typically seen as 18650 cells.?
Max charge voltage is 4.2 (consult datasheet) and max charge current less than 1C
(lower is better).
I charge them at .4C to 4.18V as that extends their cycle life (number of charge discharge cycles).
For that I use a simple CV/CC that is constant voltage (4.18V open circuit) and constant current
set to 400-500ma (depends on what I'm charging).
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If fast charging the cut off voltage is lower for safety.??
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For battery packs I charge to the max voltage for the pack example 3S 12.55V, 4S 16.75V.
As packs tend to concentrate heating I charge them at .3C as I'm in no hurry.? Its good design
to include BMS (battery protection) or CMS (charge management and battery protection)
as a safety measure.
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So for 3S (11.1 volts nominal working), 12.6V maximum, and 8.7V (absolute minimum)
are the limits.? Charge current is dependent of number and size of cells used.
my 3S4P (11AH) pack built with LG2800mah cells I use for my FT817 that current
is 1.4A (8 hour rate) and consistent with the BMS used (6A max, 12.7V cutoff).?
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==============LFE==========================================================
LFE aka LiFePo4 cells are 3.65 (some 3.7V) max voltage, current usually under 1C and .3 to .7C
is common.
I charge them at .4C to 3.65V (max) as that extends their cycle life (number of charge discharge cycles).
For that I use a simple CV/CC that is constant voltage (3.65V open circuit) and constant current
set to 2A (for my 20AH).?
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For LFE batteries with built in BMS the max voltage is generally in the data or on the battery.
A good rate is lower than needed to fully charge in 4 hours.? I generally use a 5 hour rate.
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All of those batteries? also have minimum voltage for complete discharge and if exceeded
the battery will be damaged or if built in BMS exists will make the battery unchargeable
and special charge cycle must be used (specific to the BMS and cells).
===========================================================================
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Two things notable is the Lithium tech will tolerate partial charges (you get less out though)
without impact to life of cells.? Also Lithium tech DOES NOT have memory commonly
associated with NiCd sealed batteries.? That means charging to 90% extends the life of
the battery at a small cost of 10% of it capacity (as charged).
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The other is short circuits and other faults like over voltage or current charging?
can be destructive.? ? Li tech can generally dump very large currents into a short.
or worse overheat and go into runaway ( creates a conflagration) resulting in fire.
Its why most Batteries are BMS protected as that lends a electronic self reseting
fuse.
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Note I've seen larger NiCds and lead acid do that when abused!? Simple answer is
don't abuse the battery.
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If you want to store Li tech the common voltage for that is charge to 3.5V
which is around 40-50%? and check them every 3 months or so.? That is also
the typical level of charge for new cells, so charge before use.
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More than you asked but I try to be complete.
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Experience is lithium batteries from .5ah though 400 AH.
Also assorted 18650 based packs 8.4 (2S)/ 12.6(3S)/16.8(4s)
for specific gear.
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If the voltage does not line with what the gear likes, SMPS aka buck
converters as needed.? For 12V user I like 4S packs and that gets 90%
capacity out of small packs.
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--
Allison
------------------
Post online only,?
direct email will go to the bit bucket.
Re: Calibrate the QMX's time through Android APP(FT8TW)

 

Stan,
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That was the problem.? I downloaded 93a and it works.? I guess one should not assume that the version at the top of the download page is the most current one :-)
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Brien - KE7WB
Re: At Dayton Hamvention we are seeing a revolution in amateur radio before our eyes

 

Hans:? Between your 5-watt class radios and the Aurora 500-watter, it would seem an obvious step for QRP Labs to make a 50-100-watt class radio with a good internal tuner in a KX3(ish) form factor, ideally with fine-grained?low-power settability down to, say, 1-5 watts for the QRP crowd.?
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I know you like building extra functionality in your products, bonus style points for <<1 watt (<0dBm, even?) power operation would make it into a nice piece of lab gear.? The RF power stage hardware is so simple that implementing a second, low-power-range output might be practical, all of the filtering, etc. is common, just add switches.? One could also use an independent, lower power output as a tracking generator or at a different frequency for receiver testing, to drive a mixer LO, etc.? One could even switch in a noise source, for external use or (attenuated) for built-in test purposes.?
Once you are at low power a built-in step attenuator would be practical.? The microwave power sensor guys do this, I think they are using up to 3 separate switched detectors/attenuators to get the best dynamic range.?
A lower-power capability would also be safer, as a wrong button push could not cause a 100-watt OOPS, like turning down a big transmitter could.? Been there.
Add a gating input and/or an internal pulse generator/arbitrary waveform generator and it would make a nice pulsed RF source/beacon transmitter with good linear power control for propagation estimation; maybe the key input is/could be made fast enough.??
The possibilities for feature creep are endless.
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Please keep these great products coming.? I hope you had an enjoyable visit to the States.
73, Don N2VGU
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Re: At Dayton Hamvention we are seeing a revolution in amateur radio before our eyes

 

Moderately high power RF parts for linear amps don't have much of a market, they come and go.? The MRF101 and MRF300 seem to be the primary choices these days, who knows how long they will be available.? For decades the low end amateur gear has been using the IRF510 to achieve moderately high power, occasionally with a half dozen of them in parallel.? But the IRF510 is not designed to be linear and also requires a fair bit of gate drive, making a linear RF amp a difficult challenge.? Polar modulation should ease this situation.? I've been looking at some of the GanFET's.? These can be high powered devices with very low internal capacitances.? They get used in those USB chargers that some in the forum power their radio with, the market for USB chargers is in the billions.? Unfortunately I'm very busy with non-ham related stuff here and haven't had a chance to play with the GanFET's I ordered off AliExpress last winter.
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JLCPCB is a board fab and assembly house, they charge a part cost of $0.04 for each INN650D240A they stuff, you could buy a reel of 1000 for the price of a single MRF101. ?Has a Vds_max of 650v, Id of 12a, Rds of 0.240 ohms, Qg of 2nC, Vgs_th_max of 2.7v. ?
I've never done business with JLCPCB, perhaps I don't understand their pricing.? That part was chosen almost at random, there are likely better choices.? Using this part at high power would require some fairly high power supply voltages.? Polar modulation with GanFET's could be the basis of a very cheap high powered RF amp.
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If the GanFET's really are that cheap, it might make sense to have a different push-pull pair for each band.? This would allow a current mode class D amp with the parallel resonant tank circuit directly across the drains as shown in fig 1 of the following paper. Then the output impedance matching transformer need only deal with the fundamental, the load resistance RL of fig 1 would be replaced with that transformer.? The major cost of supporting additional bands would be in the transformers.? Alternately, could use a single wideband transformer with all filtering occuring after the transformer as is typical of most RF amps today.
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Jerry, KE7ER
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On Sun, May 25, 2025 at 06:59 AM, Dave VE3GSO wrote:

It really is a big pivotal moment in Amateur Radio, and Hans with the QMX is leading the way.
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It is important to understand that such a rig can have any amount of output power desired by choosing the RF switching outputs, the size of the modulator and power supply, and ¡°linearize in software!!!¡±
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I¡¯m looking at several matched pairs of Motorola HF RF output transistors and remembering how expensive they were, and how unobtainable they are now. ?Same with Toshiba.
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Yes the world has changed, for the better in several ways. ? Thanks Hans.

Dave
Jeff Moore

 

Jeff has done it again! Repaired my mid-band QMX - a couple suspected cold solder joints and improperly wound T507 (how¡¯d I do that?). Included was a free wax and polish (Jeff removed caked solder flux and scrubs the board with alcohol). ?All done in a day or two. I had my QMX back in ten days (could have been faster but that¡¯s our slow postal service).?

it is so nice to know that Jeff is available to bail you out should your build fails. I¡¯ve built two QMXs and he¡¯s made them right for me.
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Thank you Jeff! And Hans!
(his info is on QRZ)
Phil K3UT
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Re: T507 and SSB SWR

 

There's a hidden diagnostic menu, start the terminal and from the main Menu type 'd'.
This shows a lot of raw data, ADC values for example and? at the top left are BIAS, FWD and REVS.
FWD and REVS seem to be the raw DAC values for the power/SWR meter, I see values of 4x FWD and 2x REVS with the QMX in Rx mode.? The x values are changing too fast to read.
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I connected a PTT and microphone, set? SSB mode, started the terminal in the 'd' mode and transmitted. With no sound FWD went to about 80 and REVS barely changed.? With sound FWD went to 1000 or so and REVS to about 80.? This is all with a dummy load so as expected.
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I wonder what values a system that's prone to the SWR trigger will show.
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Chris
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

 

Count me in for US buy
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Joe N7QPP
Re: Calibrate the QMX's time through Android APP(FT8TW)

 

Stan,
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Yes, thanks.? I will find 93a and try it.
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Brien - KE7WB
Re: Hi SWR, sometimes

 

Yes, I just checked and when entering the hardware tests menu, then Tune SWR the frequency shown is not what is used to transmit. You must use the encoder to adjust the frequency you desire to transmit on.
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Very good catch and thank you!
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Dean
Re: At Dayton Hamvention we are seeing a revolution in amateur radio before our eyes

 

¿ªÔÆÌåÓý

It really is a big pivotal moment in Amateur Radio, and Hans with the QMX is leading the way.

It is important to understand that such a rig can have any amount of output power desired by choosing the RF switching outputs, the size of the modulator and power supply, and ¡°linearize in software!!!¡±

I¡¯m looking at several matched pairs of Motorola HF RF output transistors and remembering how expensive they were, and how unobtainable they are now. ?Same with Toshiba.

Yes the world has changed, for the better in several ways. ? Thanks Hans.

Dave

On May 25, 2025, at 08:54, Hans Summers via groups.io <hans.summers@...> wrote:

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That Wikipedia article describes polar modulation as a form of quadrature modulation for digital encoding. That's not quite the same thing as what we're doing here to create SSB, as proposed by Kahn in his 1952 EER paper (Envelope Elimination and Restoration).

I chatted at length with Tony K1KP at hanvention and I understand he did invent it independently, though of course none of it is really new. And it was done too by Guido PE1NNZ in uSDX and (tr)uSDX. Commercially in broadcast applications and cellular.?

I don't think the point of any of this is that it's really new. It isn't. The point is that it's the first time polar modulation has appeared in high performance amateur radio transceivers. In particular it's been adopted by a big producer (Flex Radio). That's extremely significant because it's a large deviation from the well trodden path (Class A/B Linears) used by all the major amateur radio manufacturers to date. I was excited and impressed by Aurora and enjoyed all the chats at the Flex booth and at mine. It really felt like a big pivotal moment for amateur radio. Given the large gap in power levels, complexity and price, I don't think there's much overlap in customer base, so it was all very friendly.

73 Hans G0UPL


On Sun, May 25, 2025, 14:36 Sverre Holm via <svholm54=[email protected]> wrote:
Ok, thanks, so Edison thought of Polar Modulation. But in a sense which is very far away from SSB implemented by pilar Modulation.
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--
Sverre

LA3ZA
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

 

Also would be interested in a US group buy.
Re: 3 cell lipo battery, how to use it anyway

 

certainly there are devices that can reduce it and they are a solution, but as I see things....the simplest solution is the best....I prefer storage mode, 0.5 volts less than 12 volts are negligible. 73?
Re: 3 cell lipo battery, how to use it anyway

 

get a buck converter. Amazon, various ones. I have one to reduce the station 13.8 supply to 9.2 volts. I could be used easily to reduce voltage from cells as well. I think you need about 1 volt of "headroom"
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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

 

I jump in also

73 de? KQ4FT

On Sat, May 24, 2025 at 10:35?AM Dj Merrill via <groupsio=[email protected]> wrote:
Please include me for a US based group buy.
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-Dj, N1JOV
Re: At Dayton Hamvention we are seeing a revolution in amateur radio before our eyes

 

That Wikipedia article describes polar modulation as a form of quadrature modulation for digital encoding. That's not quite the same thing as what we're doing here to create SSB, as proposed by Kahn in his 1952 EER paper (Envelope Elimination and Restoration).

I chatted at length with Tony K1KP at hanvention and I understand he did invent it independently, though of course none of it is really new. And it was done too by Guido PE1NNZ in uSDX and (tr)uSDX. Commercially in broadcast applications and cellular.?

I don't think the point of any of this is that it's really new. It isn't. The point is that it's the first time polar modulation has appeared in high performance amateur radio transceivers. In particular it's been adopted by a big producer (Flex Radio). That's extremely significant because it's a large deviation from the well trodden path (Class A/B Linears) used by all the major amateur radio manufacturers to date. I was excited and impressed by Aurora and enjoyed all the chats at the Flex booth and at mine. It really felt like a big pivotal moment for amateur radio. Given the large gap in power levels, complexity and price, I don't think there's much overlap in customer base, so it was all very friendly.

73 Hans G0UPL


On Sun, May 25, 2025, 14:36 Sverre Holm via <svholm54=[email protected]> wrote:
Ok, thanks, so Edison thought of Polar Modulation. But in a sense which is very far away from SSB implemented by pilar Modulation.
?
?
--
Sverre

LA3ZA
Re: Hi SWR, sometimes

 

Ludwig,
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That is very interesting. I will check again on the frequency. Maybe that explains this:
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Working POTA around 7.060. I complete the SWR tune function and transmit with 1.5 no problem. I then move up to 7.118 and SWR protection kicks in. I clear the S and retune to get a 1.5 reading again. Try to transmit on 7.118 and protection kicks in. I retry the procedure again and the protection kicks in and no transmit. I gave up and went back down to 7.060 and transmit no problem.
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So what you are suggesting is that in the SWR tune I should turn the encoder to the frequency I want?
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Dean
Re: QDX Low Receive but Xmit fine

 

On Sat, May 24, 2025 at 02:08 PM, John Morris wrote:
The version of QDX is 1.4
John, I'm not sure what this means? A Rev 4 PCB, or the 1.04 firmware?

Either way, you need to use a terminal program to go into the QDX settings and change the audio levels there if everything else is maxed out on your computer audio. You can also have the QDX perform self-tests there to make sure each band is receiving OK. Not sure on Macs if Putty is available, or if you need some other program to do this.
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I'd also recommend using the radio as a "QDX" in WJST-X....that's been updated in the last few years.
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-Nate
N8BTR
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3 cell lipo battery, how to use it anyway

 

By doing this you recharge the pack with storage function and will have only 3.85 volts per cell at the end of the charge for a total of 11.55 volts.?
Another my hobby is rc airmodell and normally put in storage mode the cell packs when finished the flights. I use charter M6 by toolkitrc.?
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73 Luca
Re: QLG2 GPS

 

Bruce, what GPS board do you mean? The QLG2?
73 - Pierre - FK8IH
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