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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Re: #qmx Don’t Use USB-C PD to power your QMX?!
#qmx
Hans,
Also take into consideration that this issue is likely to be amplified by the rapid decrease of the capacitance of the X5R/X7R caps (in case you used them)??C102, C104, C105, C502, C507 under the influence of voltage increase (0->5V->12V).
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).
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.
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. 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.
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.
73, Guido
Hi Evan?
Yes that could be a possibility too. Doing it on the supply rail isn't because there's a capacitor on the potential divider which slows everything down too much. Yes perhaps a fast loop could run just for 5V protection.
Another possibility nobody has mentioned, if hardware modifications are to be contemplated, is just making the zener diodes bigger. What about changing the 500mW zener to a 5W type?
It also all depends what "problem" we are trying to "solve". Being able to cope with a sudden jump in supply voltage from 6V to 12V? Or something more? On Sun, Sep 3, 2023, 3:03 PM Evan Hand < elhandjr@...> wrote: Hans,
Is it possible to set an interrupt routine based on time to sample the 5-volt input and shut down the output when it reaches a threshold value greater than 5 volts but less than the 5.6-volt zener voltage?? If the timing of the power loop is 1 ms, the fast interrupt loop would need to be on the order of 0.25 ms to be effective.? This would be a very short routine to sample and shut down only.? I have used this concept in industrial control systems to handle alarm conditions with insufficient processor capability to run the entire program within the required time.?
An alternative is to store the value of the input voltage and turn off the PWM signal until the voltage stabilizes for several slower control loop cycles.
There are many strategies possible with the fast timed interrupt loop.??The A-to-D conversion times do come into play.? For the control situation, a direct read capability bypassed normal I/O processing.
73
Evan
AC9TU
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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?
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It looks like the T4857 product is thermoplastic made in Taiwan. I also have a ceramic set like Tisha which was also recommended by K7QO.
But I recently bought a vintage radio and had to buy yet another set, because none of my other tools would fit the
2mm hex cores in a vintage SX-190 that I am restoring. The Hozan D-16 is made from Delrin, but I have no idea if
that's a step up from thermoplastic.
I haven't cracked any cores yet, knock on wood...
73 de Russ, va3rr
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On Sun, Sep 3, 2023 at 11:09 AM, Tisha Hayes, AA4HA wrote: Be careful, ceramic is very fragile and you can't do anything more than
trimming adjustments, never use it as a conventional screwdriver. But it beats
the pants off of those plastic tools or the ones with the tiny metal tips.
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Re: Perfect tiny backpack setup?
#qmx
Leigh,
What's your plan for a logging program? Is it part of digipi? Is it something separate that runs on the phone/tablet (not easy integration if we're just VNC to the pi)?
--
73 Jim K1IR
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Back in the early 1980's while I worked my way through university as a bench-tech doing more than a thousand VHF/UHF radios over those years I was given a set of ceramic trimmer tools. It eliminated that entire sequence of adjust, remove tool, measure, add tool, adjust, remove tool... I could adjust while measuring without influencing the RF characteristics of the circuit. It even worked fine for doing those tiny multi-turn pots with the brass screw and the trimcaps and the hex tool for doing the slugs in inductors when peaking the helical coils.
If you do an amazon search on "8pcs adjust frequency anti static ceramic screwdriver kit" you will find what I currently use.
The original tools were just a piece of ceramic that was jammed in to a wad of rubber that was inserted in to a tiny cardboard tube.
Be careful, ceramic is very fragile and you can't do anything more than trimming adjustments, never use it as a conventional screwdriver. But it beats the pants off of those plastic tools or the ones with the tiny metal tips.
--
Tisha Hayes, AA4HA
Sr Engineer, 4RF Inc.
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Re: QDX - protection of BS17O PA
Thank you Sverre,?? I went to the link you provided and saw and read what I think I need to do.? Hope I can work you when I get my QDX's finished and tested.???
Take care and have fun.
73 Dave WA5DJJ
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Re: QDX - protection of BS17O PA
Dear Sverre,
Thank you for your explanation and you website that did a really good job of telling me what I wanted to know.? I will go find me some 47V Zenner diodes.?
Take care and have fun. I hope to work you on my QDX's when I get them finished and tested.
73 Dave WA5DJJ
SUPER QRSS/WSPR GRABBER
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N5SE
va3rr
Tisha Hayes, AA4HA