Re: QDX - protection of BS17O PA
On Thu, Aug 31, 2023 at 08:23 AM, Ted 2E0THH wrote:
The finals don't need any protection.
You are incorrect. Even a perfect antenna is subject to random events such as antennas falling down or coax faults.? A couple of diodes are cheap insurance for unforseen high-VSWR situations. --- Zach N0ZGO
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Adam,
You are close.? It would work if the Digi filter goes below your sidetone.? I do not know for sure the cutoff of the QMX digital mode filter.? I believe it goes to 300Hz, so your scenario should work.
I finished building my QMX today and have run into problems.? I believe I have fried the processor, so I can not verify using a QMX, and the QDX does not have audio other than through the computer.
I suggest that you try it and see what happens.
73
Evan
AC9TU
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Re: #qmx Don’t Use USB-C PD to power your QMX?!
#qmx
On Sun, Sep 3, 2023 at 03:10 PM, DL2ARL wrote:
so at least for the time being, I will inhibit the "handover procedure" from the linear to the 3,3V buck converter
Could this be a software/firmware option? 73, Don N2VGU
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Re: #qmx Don’t Use USB-C PD to power your QMX?!
#qmx
On Sun, Sep 3, 2023 at 02:47 PM, Guido PE1NNZ wrote:
with L101=1.5R at 12V there is a theoretical peak current of more than 4A (12-5.6)/1.5, peaking to more than 25W 4*(12-5.6), so 5W might not be sufficient.
1N5368B (47V, 5W) states max surge current 2.7A???? Another concern when considering paralleling ever-larger devices is going to be the extra capacitance of those larger diodes across the RF output, especially in the higher bands.?? 73, Don N2VGU
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Re: #qmx Don’t Use USB-C PD to power your QMX?!
#qmx
On Fri, Aug 11, 2023 at 05:38 AM, Shirley Dulcey KE1L wrote:
Cell phone chargers are often in the category of only delivering 5V or 9V
Most gentle Ladies and Gentlemen, I humbly think that the PowerSupply Railway-Exchange we are all driving trough is for one reason unnecessarily complicated. I try never to raise oppinion against something if I do not have a better alternative. But in this case, I do. It is not my idea: I read about it in: CQ March 2015 QRP Special Page 18:? Behold Rockmitey, de ED Cobb? K4YFR es Ray Kauffman ?AJ4YN. Look what happens. Basically we need 5V to operate the radio (disclaimer: most of our qrp radios). In some cases we also need 3,3V, but that set apart, let us stick with the magic 5V level: because of USB and Cell-Phones 5V has become the standard of our age. What we do in most cases is so wrong, in so many ways: we probably start with the voltage of a single 3,7V LiPo Cell built in some Power Bank. The built-in converter (most probably of a some noisy, very bad efficiency) boosts this voltage to 5V. Than we use maybe another internal Boost-UP-Converter, maybe an external one to increase 5V to the 12V expected at the input of the (qrp) transceiver. We feed the 12V into the rig of our choice, where, for the most of the time it gets down-converted to 5V (and probably to 3,3V too) with another efficiency loss. The 12V is only needed for the short TX Phase. I do not know what your mileage is, but for me, I am an SWL, most of the time, probably 90% of the time I spend on the HAM bands. I listen most of the time and transmit just now and then. So why travelling trough this complicated UP-and-DOWN Railway-Exchange anyhow? What do I do instead? Following the learning done in that CQ Magazine quoted above, I have modified some of my MTR-Transceivers (superb KD1JV designs) for the following path: I start with 2 LiPo cells, yielding together 7,4V. This choice has another advantage: for a reason I do not know, it is much easyer to find a solution to charge a 2Cell LiPo battery than it is for a 3C or even worse for a 4C battery. A 2C pack not only can it be easily charged, but it also gets well balanced. This 7,4 V supply is in MOST Cases enough for the MTR to offer a HF output at the qrp-qrpp border. In most cases enough for me. For the eventuality I would try to go up to "full legal qrp power", I use a Boost-Up converter to 11..12V that is only active during the TX phase. The transition could be made automatic (like described in the CQ article), driven by some PTT Level in the rig, but because I do not use this option often, it remains for me a manual switch.? For the rest, using a LDO, I convert the 7,4V to 5V and feed the Rx Part of the MTR bypassing it's internal converter, whatever of a sort this one might be. Because of the relative low current consumption of the Receiver in the MTR, the conversion loss is minimal and not to be taken into account. The MTR5 even has an internal buck converter for this purpose. Whatever I did, whatever I do suits best my needs. But in order to be able to do so, I had to modify the existing rigs to fit my needs. It would have been much easyer and straight forward if they would have been designed for a wiser and more modern Supply Voltage Railroad-Exchange. The QMX is a huge step ahead, but not in this direction. And because of it's adventurous behaviour, I will probably not feel at ease with it, so at least for the time being, I will inhibit the "handover procedure" from the linear to the 3,3V buck converter and at least feel safe, in the event I will not be. If we like it or not (I do not!), we live in a USB dominated world, we must use LiPo cells and both of them are very badly suited for our old habitual 12V, voltage probably coming from the stone-age of electric development related to those lead-acid batteries formerly used in gasoline eating cars ... just thinking loud. yours friendly, Razvan dl2arl
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I have measured Doppler Shift on WWV due to a moving ionosphere, both when it is transitioning from day to night and vice versa, and to a lesser extent due to gravity waves in the ionosphere. ?It is on the order of tens of milli-hertz. ?So not really obvious to the casual observer, but really cool to this FMT nut. Dave
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On Sep 3, 2023, at 12:43, Jerry Moyer via groups.io <ac5jm@...> wrote:
? I don’t mean to start an argument here but I have never associated Doppler shift with an RF path between 2 FIXED objects where the distance between them does not change. ?When the transmitter is at a fixed location and the receiver is at a fixed location, where is the movement happening that causes the Doppler shift? ?Aren’t we really talking about multi-path cancellation? ?That commonly affects VHF and above. ?The way to deal with multi-path is to use multiple polarization or even circular polarization at one or both of the antennas. ?Am I missing something??
-Jerry AC5JM? On Sep 2, 2023, at 3:01 PM, Da Amazin' man G0FTD via groups.io <punkbiscuit@...> wrote:
?On Sat, Sep 2, 2023 at 08:22 PM, GIUSEPPE wrote:
Good evening everyone, I agree with what Jerry wrote, the WSPR propagation does not determine the openings in SSB,
WSPR allows a typical signal of 30db below the noise to be confirmed depending upon the decode engine used. 1 watt of WSPR = 1000 watts of SSB for a typical S1 signal of SSB. If you get a decode of -30db on WSPR then you need 1000 watts of SSB to make the trip with an S1 signal. WSPR reveals a path, but it doesn't guarantee that some some one on SSB is listening, or has 1kw ERP to make the trip. Whence the disparity of WSPR reports vs actual SSB QSO's. -- - 73 de Andy -
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Re: Successful QMX build - and some bug reports
#qmx
On Tue, Aug 29, 2023 at 11:44 AM, Matt - HB9HWI wrote:
In CW Mode (actually what I want to use the QMX for):
Audio issues:
- Sidetone volume can’t be adjusted. It’s either rather quiet, very loud or changes with the AF volume.
- AF volume can’t be turned down to zero. I can always hear a strong station.
- Missing AGC is really an issue and I currently refrain from using the QMX for CW for that reason.
Like you, I have not been able to adjust the sidetone volume. I find it changes with the AF volume. Does anyone know if AGC will be coming in a firmware update? Apart from that, my QMX seems to be working fine. I have been having fun with the terminal and looking at the sweeps. Thank you again Hans for a great kit. ? ? ? ? ? ? ? ? 73 de OE6FEG/M0FEU ? ? ? ? ? ? ? ? ? ? ? ? ?Matt
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Evan Hand <elhandjr@...> wrote: the short answer is yes for most cases. ?For example, if you use the
WSJT-X tune function the actual frequency is the set point (7.074) plus
1000hz. ?For CW the dial frequency is the transmitted frequency. ?That
is not true for all radios and some can be set to shift the transmitter
instead of the receiver. Ok, so to help me get this straight... I set 14000 kHz and switch to digi. Someone in WSJT-X transmits at 14001 kHz (14000 kHz + 1000 Hz). I can hear a 1000 Hz tone, and my WSJT-X will show it at 1000 Hz mark. That's clear. Now I still have 14000 kHz set, but switch to CW. My sidetone is set to 500 Hz. Someone transmits at exactly 14000 kHz. I will hear the 500 Hz tone, right? If someone transmits at 14000.050 kHz (50 Hz more than my set frequency), I will hear 550 Hz, and if they transmit at 13999.950 (50 Hz less than my set frequency), I will hear 450 Hz, right? If someone transmits at 14001 kHz I won't hear it, because I'm centered at 14000 kHz and the CW filter isn't wide enough to cover it. If I press PTT, I will send a continuous wave of exactly 14000 kHz. So, generally, when I'm sweeping the CW band in a digi mode and I hear someone sending, I wouldn't be able to hear them when I switch to CW, because I should first increase the frequency to zero-beat on them (so I stop hearing them in digi mode), and then after switching to CW I would hear them at my sidetone frequency. Is it all correct, or am I wrong somewhere? I am typing this on my phone at a concert with my wife. If you need more
info send back your questions and I will respond tomorrow. Great, thanks!
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Re: #qmx Don’t Use USB-C PD to power your QMX?!
#qmx
Q=C*U? where Q is constant, but C decreases (e.g 10%) under the influence of increasing U -> making U even higher (e.g. 10 times higher).
I didn't get that bit...
What I?had in mind is the capacitance-loss that comes with X5R material when DC-voltage increases: e.g. a 100nF cap becomes 90nF at 5V and 10nF at 12V. Now when this capacitor is charged at 5V the charge Q = 5 * 90nF = 450n. Now when stepping the 5V to 12V the capacitance suddenly becomes 10nF, but since we already had 450n charge the new voltage becomes a voltage spike of 450n / 10nF = 45V. Does this make sense? I could be mistaken.
If PD start up somewhat faster than 250ms then there isn't any problem anyway.?
There seems?to be a USB PD settling time of max. 275 ms specified in which a PD source must have the new voltage stable, probably this is after the negotiation starts, do not understand yet if there is an upper limit on that. ? So my question is still... Wouldn't just making the zener diode bigger fix the sensitivity to this unusual supply scenario? In my tests, with the standard circuit (500mW zeners) I was able to do 6V to 9V, 10V, 11V steps without issue and the zener ate the brief over-voltage. It even did on 6 to 12V steps but not every time. So given that it almost works even with the 500mW zeners isn't it worth trying a 5W zener say, being optimistic that it may be able to swallow that extra current for a millisecond? Then if QMX has a specified supply voltage range of 7V to 12V say, you'd be able to do anything at all with the supply voltage in that range without any fear of damage.
True, that using bigger diodes might fix it eventually, the transients are?short. But on the other hand with L101=1.5R at 12V there is a theoretical peak current of more than 4A (12-5.6)/1.5, peaking to more than 25W 4*(12-5.6), so 5W might not be sufficient.
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On 03/09/2023 16:43, Jerry Moyer via groups.io wrote: I have never associated Doppler shift with an RF path between 2 FIXED objects Jerry, The ionosphere moves. There is a small Doppler shift of sky wave signals, often less than 1Hz. But it can be very large in auroral conditions. The stations do not move but the refracting area does. 73 Alan G4ZFQ
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Not sure what that was a picture of, but it got mangled by compression artifacts while being transmogrified for the mailing list. ?8*)
73, Willie N1JBJ
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On Sep 3, 2023, at 2:07 PM, Da Amazin' man G0FTD via groups.io <punkbiscuit@...> wrote:
Hi Jerry,
Thanks for pointing out that I'd used incorrect terminology in my last post.
I should pointed out that it really multipath when the HF signals for example traverse
over the North Pole for example, or near? the aurural zone, and they end up getting
badly hammered.
I've attached a spectrogram of? a couple of WSPR traces as seen in KL7 from Europe on 20m.
No amount of checksums are gonna decode that on data signals ;)
That's typical most days on such a path.
On? bad day you can see the traces get mangled by 30Hz of more.
--
- 73 de Andy -
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Re: QMX: Kit Build complete - My observations
Hi,
My +12V QMX draws from 89 mA to 95 mA on RX from 80 m to 20 m respectively.?
Without the audio signal (phones) present.
I think Hans has pushed the parameter a little bit once again (Hi) by saying the current was 80 mA.
Or, perhaps I am loosing that 15 mA somewhere.
For the High band QMX it will be even a bit more.
73 Bojan S53DZ
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Hi Jerry,
Thanks for pointing out that I'd used incorrect terminology in my last post.
I should pointed out that it really multipath when the HF signals for example traverse
over the North Pole for example, or near? the aurural zone, and they end up getting
badly hammered.
I've attached a spectrogram of? a couple of WSPR traces as seen in KL7 from Europe on 20m.
No amount of checksums are gonna decode that on data signals ;)
That's typical most days on such a path.
On? bad day you can see the traces get mangled by 30Hz of more.
--
- 73 de Andy -
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Dean,
Mine is a late version a few months old and unused.? My thought was to try one after the other, same antenna and QTH.? If there's a problem with one, the other should have similar results.
73 Paul KY4XJ
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Re: #qmx Don’t Use USB-C PD to power your QMX?!
#qmx
Here is an external work around, where the USB-C PD output can be user selected.q
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Re: #qmx Don’t Use USB-C PD to power your QMX?!
#qmx
Hello Guido
Q=C*U? where Q is constant, but C decreases (e.g 10%) under the influence of increasing U -> making U even higher (e.g. 10 times higher).
I didn't get that bit...
Indeed, with L101 about 1.5R or so supply?DC-resistance, the 1ms software control loop is way too slow and should be in the order of 4ns response time to correct the voltage in C107, difficult to achieve in a ADC polling fashion so this is probably a NO GO as it would have a serious CPU cost.
Yes the 1ms control loop isn't a cycle by cycle correctionams this is why it can have trouble with sudden large changes.?
A simple workaround could be to DELAY the use of switching regulators after powering up. This allows the USB PD device to do the voltage jumps just while only the LDO is active, and limits the sensitivity in all these control loops that are anyway too slow to resolve this issue.
The switching regulators are already slow to start up, around 250ms. How long does a PD device need? I could add a configurable additional delay.
As soon as there is a voltage drop (due to a bad cable) you could redo the complete power-up procedure to also be immune in that circumstance.
No because you'd have to detect that and react to it. Same problem.
My view on this is that all effort you put in making the control loops faster will eventually still insufficient to deal with this USB PD voltage steps.
If PD start up somewhat faster than 250ms then there isn't any problem anyway.?
In the history of QRP Labs there have always been cases of people using power supplies that don't go too well even back to the Ultimate2 in 2014. Supplies with unexpected spikes etc. It isn't surprising that we've found with QMX a couple of people who've had trouble with a particular powering arrangement. Such as the 6V to 12V step. Is it indicative of a general weakness? No. Should it be something that if possible gets improved so QMX gets more resilient?
The zeners are in place for dealing with unexpected power excursions. However as demonstrated by Gunnar they can't manage a step 6V to 12V. Even after I had improved the response speed drastically for supply steps in firmware 1_00_009.
So my question is still... Wouldn't just making the zener diode bigger fix the sensitivity to this unusual supply scenario? In my tests, with the standard circuit (500mW zeners) I was able to do 6V to 9V, 10V, 11V steps without issue and the zener ate the brief over-voltage. It even did on 6 to 12V steps but not every time. So given that it almost works even with the 500mW zeners isn't it worth trying a 5W zener say, being optimistic that it may be able to swallow that extra current for a millisecond? Then if QMX has a specified supply voltage range of 7V to 12V say, you'd be able to do anything at all with the supply voltage in that range without any fear of damage. 73 Hans G0UPL
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I don’t mean to start an argument here but I have never associated Doppler shift with an RF path between 2 FIXED objects where the distance between them does not change. ?When the transmitter is at a fixed location and the receiver is at a fixed location, where is the movement happening that causes the Doppler shift? ?Aren’t we really talking about multi-path cancellation? ?That commonly affects VHF and above. ?The way to deal with multi-path is to use multiple polarization or even circular polarization at one or both of the antennas. ?Am I missing something??
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On Sep 2, 2023, at 3:01 PM, Da Amazin' man G0FTD via groups.io <punkbiscuit@...> wrote:
?On Sat, Sep 2, 2023 at 08:22 PM, GIUSEPPE wrote:
Good evening everyone, I agree with what Jerry wrote, the WSPR propagation does not determine the openings in SSB,
WSPR allows a typical signal of 30db below the noise to be confirmed depending upon the decode engine used. 1 watt of WSPR = 1000 watts of SSB for a typical S1 signal of SSB. If you get a decode of -30db on WSPR then you need 1000 watts of SSB to make the trip with an S1 signal. WSPR reveals a path, but it doesn't guarantee that some some one on SSB is listening, or has 1kw ERP to make the trip. Whence the disparity of WSPR reports vs actual SSB QSO's. -- - 73 de Andy -
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Rick (NF6G),
SMA, that I understand. All of my low powered interconnects use SMA. Quite successfully I might add.
Thanks very much, Billy (N5SE)
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Billy, I believe what Paul was referring to is an SMA connector.
-- N5SE
Billy Wayne Moore
7066 Shady Knoll Ln
Willis, TX 77318-6324
Phone: 936-537-2975???
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Billy, I believe what Paul was referring to is an SMA connector.
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Ok, I have searched and cannot find out what an ama connector is. Can you please explain?
I have wired my whole shack with RG-6 Quad Shield using type F connectors. Yes, do understand it is 75 ohm, but have solved that problem. Have 75 ohm SWR bridges to start with. Was restricted to VHF/UHF for a few years and came upon a good supply of Quad Shield.
Just like uhf cable and sattalite, the Quad Shield beat the regular plain coax. I've got it now, so I have to use connector adaptors on all my current rigs.
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Don,
the condition of your QMX reflects exactly what I'm getting.? I've built several qrp-labs kids but never had a sound issue. I just wondering if we are unlucky and have a duff board. on a side issue my BNC connector was so stiff that today when I unplugged the
coax cable it pulled the innards of the board bnc. connector with it breaking of the pin making it basically non repairable. I'm gonna replace it with an ama connector as I believe Hans has provided for both types of connectors.?
Paul DJ0CU G4ADF?
-- N5SE
Billy Wayne Moore
7066 Shady Knoll Ln
Willis, TX 77318-6324
Phone: 936-537-2975???
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Donald S Brant Jr
DL2ARL
Matthew Pullan
N5SE