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QMX shows high SWR
A few months ago I successfully built the low band QMX, and it was fully working. This week I had a short interruption of the power supply, resulting in a blown D108. I replaced it, and also updated to FW 1_00_016 (was 1_00_010 before). Connected a dummy load, did a couple of tests, and everything seemd ok. Then I connected the antenna, receive is good, but as soon as I TX, the SWR protection kicks in. I checked the SWR of the antenna with my IC7300, and it shows 1:1. Re-checked with analyzer, it also shows perfect SWR, so I'm pretty sure the antenna is good.
I disabled the SWR protection, sent a quick CW and was immediately spotted in RBN, so TX works. If I TX into the dummy load, no/perfect SWR is indicated and TX works, but into the real antenna, it shows high SWR and shuts off. Any ideas, what could be wrong? Tnx Robert |
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Re: oscilloscope use
Oscilloscopes all have very similar controls, your text should be applicable to them all.??
I have 2 Hantek 'scopes, one the box type and the other essentially identical except that it is headless; all of the controls are on an application which runs on a computer. The box type is more portable, the headless has an arbitrarily-large display. And don't skimp on bandwidth; 50MHz is barely adequate for 10 meter work; I went for the highest available at the time, 4 channels @100MHz.? 2 channels may be enough for your needs. I also opted for the internal tracking generator. Don't forget to budget for quality 10X probes if they are not included with the 'scope.?? I started my career in the '70s using Tektronix 'scopes with storage CRTs.? If you are used to those analog 'scopes you are in for a pleasant surprise as regards storage and triggering capabilities and convenience.? Hantek, Rigol, Siglent are all respected name brands in this mid-tier space.?? 73, Don N2VGU |
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Re: QMX locks up during keying practice
I believe that in the newest firmware as of now (016) that the QMX will mute the sidetone when the transceiver enters protection mode. But that should not make it lock up.
I experienced a total lock-up of the QMX while in practice mode one time earlier this week which surprised me. But it hasn't happened since. I run Iambic B at 22 WPM when practicing. I don't use a dummy load, I put the QMX in Practice mode (which prevents it from transmitting RF). It's possible that something with your dummy load setup, like an unreliable connection somewhere, is allowing RF back into the QMX, which can definitely manifest itself as a total lock up. If it happens to me again whilst in practice mode, I'll report back. 73 Roy - KI0ER? |
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Re: IQ mode Enabled on version 16
#qmx
Thanks Hans,
Installed V17 and the digi enablement is working perfectly.? Very happy. 73 de ZR6TM Timo |
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Hi all I have released firmware 1_00_017 at The most important features are the AGC and S-meter.? S-meter: it appears in the 3 characters to the right of the mode indicator character, when S-meter is enabled. The 15 vertical bars are worth 6dB each and therefore correspond to levels from S0 to S9 (9 bars) and?on up at S9+6dB, S9+12dB etc to S9+36dB when all three are full solid. The scale is calibrated in real decibels, but the accuracy of S0 relative to an actual signal input depends on the level of the gain setting you set for various bands in the Band Configuration terminal menu.? AGC: it's a quite complex sub-system and I have documented the concepts and parameters in the 1_00_017 operating manual at , section 5.21 pages 52-57 inclusive. Briefly...? AGC operates in the decibel domain, not linear. There is an AGC threshold below which AGC does not operate, it's a parameter specified in S-meter units. There's an impulse noise filter whose duration is configurable. The AGC slope is configurable so you can adjust it to your taste, you can have a gentle AGC action where strong signals are louder than weak ones, or an aggressive one where the AGC system makes everything the same volume. Hang time and recovery rate are also configurable.? The AGC system creates an audio sample delay line, which it analyzes for impulse peaks then applies the calculated AGC gain (attenuation) to the sound samples in the delay line. The action of the AGC is therefore effectively instant; no matter how strong the incoming signal, the time taken for the AGC to react to it and protect your ears is always zero,?no piece of strong signal reaches your ears. The length of the delay line is configurable and needs to be a minimum 1.3ms for CW. SSB has a lower minimum audio frequency so a longer delay line is required; the maximum configuration is 6ms which would be able to handle signals down to 83 Hz. Either way, it's a very small latency.? The S-meter also has a configurable "AGC action" display; if enabled, the S-meter looks like the Power/SWR meter function (during transmit) with two bars. The upper bar is the S-meter and the lower bar is the AGC action, with a configurable number of dB per pixel. It just helps you to see when AGC is active.? The S-meter configuration parameters were moved to their own sub-menu under the Display/controls menu, and include an S-meter update interval parameter.? I created a short demonstration YouTube video? . In this video I used a QCX, with about 150cm of wire attached to the antenna port, to generate a strong CW test signal. The BS170s in the QCX are toasted so this just produces very little actual power output but of course we are in close proximity, so the signal level "received" by the QMX is enormous, approx S9+30dB. In the video you can see heavy clipping when the AGC is off, which would no doubt generate a gigantic headache if you had earphones on; when I switch AGC on the signal is reduced to a comfortable S9 level.? I also tested the QMX with AGC on 40m at night, tuning around for strong signals with and without AGC and I believe it is highly effective.? The system is highly configurable, I suspect it may be TOO configurable; I will look forward to your feedback and suggestions on how it may be improved, and in particular it may be possible to remove some of these configurations, or derive or calculate them. The attached screenshot shows the configuration I used for the video. I must say though that it does not appear to be a delicate act, balancing parameters carefully; it seems generally to be very effective and insensitive to the exact settings.? I do highly recommend though that you read the operating manual pages 52-57 carefully; initially all the parameters will be zero and you need to set it up carefully, before enabling AGC. At the moment there are no default values. So let's see.? Other than that, I also added an LPF sweep tool (see example attached), which was discussed some time ago here. It "transmits" at 1/4 full power, into a dummy load (DO connect a dummy load!) while sweeping the transmit frequency, and plots the measured power output, after conversion to dB and normalizing the center frequency measurement as 0dB. It's indicative only, but quite interesting to see and educational, perhaps useful for debugging too.? Plus a couple of bug fixes; change list is:
So that's my week's work here.? 73 Hans G0UPL |
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Re: IQ mode Enabled on version 16
#qmx
Thanks mate, very nice of you to give this attention.
73 de ZR6TM Timo |
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Re: oscilloscope use
开云体育Is this book only available as a kindle version? I would prefer
good old fashioned paper if it is available! On 14/02/2024 06:39, Fernando TUSELL
via groups.io wrote:
I found this little book of use: |
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Re: An interesting diagnosis
Great work, Jeff, and good luck with the micro replacement! 73 JZ KJ4A? On Fri, Feb 16, 2024, 2:34?AM Andrew Lenton <a@...> wrote: A very interesting write up well done, not sure if I would have got there!! |
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Re: QMX V3? What does V3 bring?
?Hi?Gottfried Is it advisable to add mods 2, 3, 4, 6, 7 and 8 to old Rev 1 boards as well? There aren't any documented problems attributable to these issues on Rev 1 boards. The modifications 2, 3, 4, 6, 7 and 8 would work fine on a Rev 1 board. However - when you replace SMD parts there's a risk of damage to the board. Therefore I would in general, stop short of recommending these modifications be made to Rev 1 boards. In general I find that remembering "if it ain't broke, don't fix it" normally works very well for me.? 73 Hans G0UPL |
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Hi all QMX kits: FINALLY after some UNNECESSARY delays and FedEx FRUSTRATION Arrrggghhhh we finally got the 8 boxes of 1,000 QMX Rev 3 boards yesterday afternoon. My team are building two for testing right now. I don't expect any issues. My team are also flashing the bootloaders. The other components and enclosures are already prepared. Subject to successful testing we'll begin shipping the pending QMX kit orders today; there are around 250 orders pending so it will not happen instantly, but I hope we can clear the backlog within a week.? QMX Assembled (and QCX-series, QDX-series): See attached: we are making good progress on reducing the size of the backlog. The assembled radio waiting list is here: and I update it normally every weekday unless I have a brain lapse. It currently stands at 815 orders, down from a peak of 906.? Any urgent requests, please let me know.? We have two new employees starting on Monday. Which reminds me I need to order some new soldering irons and solder today otherwise that's not going to help us much, is it :-/? ?And we have a carpenter building two new 90 x 270cm tables for our 4'th room up here in QRP Labs towers.? 73 Hans G0UPL |
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Re: IQ mode Enabled on version 16
#qmx
Hi all I resolved?this issue in the forthcoming 1_00_017. 73 Hans G0UPL On Wed, Feb 14, 2024 at 9:41?PM <timo.vandermerwe@...> wrote: Thanks Adrian and Jim, |
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Re: PWR/SWR meter with FW #16
Hi Tim It isn't a bug, it's a change to the way the power meter operated; in 1_00_016 there are some additional parameters in the new "Pwr/SWR display" configuration screen (see attached). The reason you don't see power on dits is because the update interval you have, is too long, and the dits are fitting in between the power?meter updates; just make the update interval a bit shorter and it will fix it.? 73 Hans G0UPL On Fri, Feb 16, 2024 at 9:19?AM Tim Keene via <k5dez=[email protected]> wrote: ?I'm not sure if it has already been reported or noticed yet but I have a low band Version 1 QMX and a High band V2 QMX. With FW #14 the PWR/SWR meter works fine but when I install FW #16 the pwr/swr meter only works "normally" with the Dah paddle. If you hold the Dit paddle only one line of pixels come up and does not show the power or swr correctly. If I reinstall FW #14 again all is well. Can anyone else produce this "bug"?? Let me know please. |
Donald S Brant Jr
K9NUD-Steve
Andrew Lenton
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