Re: SWR Protection QMX mini
If I were in your shoes I would leave the SWR protection enabled. 3:1 is a reasonable threshold.
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Maybe you could double check your antenna and coax performance by using the ¡®Hardware Test¡¯ > ¡®SWR Tune¡¯ mode and monitor the SWR while fiddling with the antenna and feedline and see if you can pinpoint some instability.
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Re: SWR Protection QMX mini
An end-fed half wave needs a 49:1 transformer, not a 9:1! So that's probably not helping you any!
9:1 is used with end-fed random wires.
However, assuming for the moment that was a typo, the main times I've seen SWR change on me with? an antenna that started out "good" was when it was overheating. It's unlikely 5 watts is overheating it (unless it is in fact a 9:1, in which case, the impedance mismatch means all bets are off). Is it in direct sunlight or something else that might be heating the transformer?
Michael WD0OM
On Thu, Sep 19, 2024, at 14:17, Jack Kibelbek via groups.io wrote:
I¡¯m traveling in GB and attempting to activate several POTA parks while I¡¯m here. ?I¡¯m away from my test equipment and I¡¯m soliciting advice.
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I took my QMX low band and a 20m QCX for backup. I have a 12v Talent Cell power bank. ?Antennas are 20m and 40m EFHW that tested less than 1.5:1 SWR on 20m and 40m (also less than 1.5:1 on 20m with the 40m EFHW) both fed through 20 ft of RG-316 and a 1:9 UNUN.?
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My QMX is set to SWR protection ON at 1:2. ?When I start calling CQ, I can call off and on for about 10 minutes, then the SWR protection will shut down transmission. Rebooting the QMX will restore transmission for a bit. ?But after another 15 minutes or so, it¡¯s shutting down about every 2-3 minutes. Today I reset the SWR Protection to 3:1. ?It took a bit longer, but it was still shutting down about every 5 minutes. ?I switched over to using the QCX.
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I know that an antenna¡¯s tuning and SWR will vary from site to site according to the height, ground conductivity, etc,. ?But these antennas were fine at home. If the SWR is really above the set value, why does it take so long to trigger? ?
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Any idea what¡¯s going on? And any suggestions? ?Shall I turn the SWR Protection OFF?
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Thanks.
Jack N8EU
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I¡¯m traveling in GB and attempting to activate several POTA parks while I¡¯m here. ?I¡¯m away from my test equipment and I¡¯m soliciting advice.
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I took my QMX low band and a 20m QCX for backup. I have a 12v Talent Cell power bank. ?Antennas are 20m and 40m EFHW that tested less than 1.5:1 SWR on 20m and 40m (also less than 1.5:1 on 20m with the 40m EFHW) both fed through 20 ft of RG-316 and a 1:9 UNUN.?
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My QMX is set to SWR protection ON at 1:2. ?When I start calling CQ, I can call off and on for about 10 minutes, then the SWR protection will shut down transmission. Rebooting the QMX will restore transmission for a bit. ?But after another 15 minutes or so, it¡¯s shutting down about every 2-3 minutes. Today I reset the SWR Protection to 3:1. ?It took a bit longer, but it was still shutting down about every 5 minutes. ?I switched over to using the QCX.
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I know that an antenna¡¯s tuning and SWR will vary from site to site according to the height, ground conductivity, etc,. ?But these antennas were fine at home. If the SWR is really above the set value, why does it take so long to trigger? ?
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Any idea what¡¯s going on? And any suggestions? ?Shall I turn the SWR Protection OFF?
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Thanks.
Jack N8EU
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I fell over this a few minutes ago:
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The description points to the blog of jp3dgt:
https://jp3dgt.blog.fc2.com/blog-entry-868.html
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in japanese but google translate makes a good translation.
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73 de oz9ny, Niels
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Re: QMX just built with 2 (?) issues, for advice
Thanks very much Dave
I have reset, and gone into the menu.?
Can change bands now; ok.?
Now low out put on all bands ?- between 1.5 to 2.5 w across bands.?
I¡¯ll try diagnostics if I can get it wired for that.?
Thanks again for your help ¡ appreciated.?
Cheers
Dan VE7CTN
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Interesting measurements.
In your second post that updated the statement of the failure, you said that you had the external device connected to Vcc (5V), not Vdd (3.3V).? Is that correct? Or was it the 3.3V rail?? or both?? The answer to this definitely guides the troubleshooting process.
Being on the 5V Vcc supply is why I said you should check Q108 and Q105, since a back-voltage on the 5V rail should hopefully only affect this part of the circuit.
And your test shows that Q108 is likely blown, which would prevent the 5V Vcc supply from coming up.? The failure could also have damaged other components in that same part of the schematic, to the right of Q105.? Only tests/measurements could say for sure.? If there is a blown component that shorts to ground (e.g. D106), it could cause significant current draw on the 12V line.
But your tests also show something holding down the output of the 3.3V Vdd supply.? So obviously something is wrong here, too.? The only thing connecting across these two supplies is the 12V line, and it is getting enough voltage to power IC101.? Note that normally, the IC101 3.3V is only 'on' for about 1/4 second right after power-on, while the firmware boots and enables the more efficient 3.3V supply.? This is obviously not happening, so the mcu is never getting enough voltage to boot.? I'm not sure exactly what to look at next, but with the output of IC101 lifted, and power_on set, I would check the voltage on the 12V line, and at the input and output of Q109, Q111, Q108, and test D103.? That will give some additional data points to guide the debugging...? Good luck.
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Re: Question about QMX mid range assembly manual (assembly_1_04b.pdf)
Colour coding has saved me from a senior's moment or three ?
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On Thu, Sep 19, 2024 at 11:52 AM, Joe AI5DD wrote: I love the green!
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Re: Zeners Diodes in a QMX mini
4. Always use the 'tune SWR' feature of the QMX while tuning (menu -> hardware tests -> tune swr).? This is less convenient than just keying, but reduces the output power while tuning to 25% by default, and you can set it lower.? Similar effect to adding the 6dB external pad.
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Re: QMX just built with 2 (?) issues, for advice
Hi Dan Re band selection, check out? section 5.17 in? QMX operation manual:? "System config
This menu contains several system configuration parameters which don¡¯t seem to belong in any
other menu.
Band version
80-20m
Displays the band version of your QMX. You will have selected this at first power-up of your QMX.
You can change it in this menu but the Band Configuration and other parameters will not be
changed to reflect it; if you have chosen the incorrect band version at power-up and wish to reset
the configuration appropriately for the version you built, the best way to do this is using the Factory
Reset feature."ng The momentary reset on transmit you are experiencing sounds like external power supply voltage collapsing on increased current during TX Running diagnostics using Putty will shed some light on the issues you have. Hope this helps a little. Cheers Dave VE7AHT
On Wed, Sep 18, 2024 at 9:12?PM Dan Marriott VE7CTN via <danmarriott= [email protected]> wrote: Hello,
Just completed my QMX mini (20-10m).?
Loaded firmware without issue - use 9 volt battery at about 8.5 v.
Initial test with same battery .. low battery indicator, so switched to 9 volt LiFePo at 10.25v.
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Issues
- stuck on 20 meters, can¡¯t change bands.? All other menu functions seem normal. But band changing won¡¯t work.
- when keyed into a 50 ohm dummy load, the rig shuts off temporarily as if ¡°protection¡± was kicking in, as it boots back up immediately. ?
Suggestions?
Thanks,
Dan VE7CTN
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Re: Question about QMX mid range assembly manual (assembly_1_04b.pdf)
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Re: Question about QMX mid range assembly manual (assembly_1_04b.pdf)
Good catch. It should read "15 turn tap" to correspond with the photos.
I wound my L405a with green magnet wire.
GL de va3rr
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Re: Zeners Diodes in a QMX mini
On Thu, Sep 19, 2024 at 09:16 AM, Chris KB1NLW wrote:
Two things:
- Even with low SWR there can be high voltages at the finals (particularly on the lower bands).
- There are very fast high
3.? Use an absorptive bridge or 6dB pad between radio and tuner.? Make sure tuner doesn't tune after you remove/bypass the bridge/tuner.? I switch tuner off, the latching relays stay put.
73, Don N2VGU
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Thank you everyone. I went back to touch up the solder joints and noticed that R303 had gone missing ?. I'll address both now.
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Question about QMX mid range assembly manual (assembly_1_04b.pdf)
QMX: QRP Labs Multimode Xcvr (transceiver)
Assembly manual
--- PCB Rev 4 ---
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When reading the section for 60 / 40 / 30 / 20 / 17 / 15m version page 38,?talking about twisting the 15th turn in?Step 4 it continues on and says "section at the 19-turn tap gets tinned with solder nicely and evenly and easily."?Did I miss something? Does this refer to the 15th turn? I just want to be clear.
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Re: W2LI Magnetic Loop Antenna - Anyone Use This?
Hi -?
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Update on this - I have purchased one of the W2LI loops (to be delivered soon) and I will give feedback on how it performs on each band (40, 30, 20, and hopefully 17).
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We will see how good or bad it is with 5 watts - I'll test it using WSPR first.
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John - W3JED
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I push pieces of component lead cutoffs through the holes and solder them to the encoder leads to make a more solid connection.?
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73, Dan - W2DLC
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Re: Zeners Diodes in a QMX mini
Two things:
- Even with low SWR there can be high voltages at the finals (particularly on the lower bands).
- There are very fast high voltage spikes caused by automatic tuners that are too fast for the protection.
Hans will be taking care of (1).
For (2), at this time, only use an ATU with great caution to prevent tuning at full power.
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Please see this message: ?/g/QRPLabs/message/129999?
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Re: Zeners Diodes in a QMX mini
Why not take advantage of the SWR protection feature in the QMX? It seems to be a very capable technique to protect the finals.
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Is there a trend QMX BS170s blowing despite SWR protection?
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What Andy said about proper soldering of the encoder leads is right on.
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I had a QMX with an encoder issue and when I tested continuity with a DMM everything checked out. Turns out there was a hairline gap between the encoder pin and the solder pad that I couldn¡¯t see with my eye and the slight pressure from the meter probe was enough to close the gap.
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A rather pernicious problem, fixed by simply adding a bit more solder to the junction.
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Keith <keithlewis25@...> wrote: I recently finished building the QMX kit for 20 to10 mtr bands.
Everything seems to work ok but I am unable to get the transmitter side
working. I have gone over the board looking for bad joints and possible
shorts but everything seems fine as far as I can see. Can anyone get me
any suggestions how I can debug the tx side. Be grateful for any
suggestions. "Doesn't work" is a broad statement. What happens when you try to transmit? Something changes on the display? Current consumption is the same as when receiving? Are you sure that QMX is receiving audio? Have you tried the diagnostic menu? Go to Hardware tests -> Diagnostics. What happens when you press (and hold) P there? When I press P, I see the BIAS SMPS change status to ON, current around 30 mA, duty cycle around 14 %. Connect dummy load and press (and hold) T. When I do it, in addition to the BIAS SMPS, in the TRANSMITTER section I can see: Voltage: 10.0 V (it's 0.7 V without T pressed) Power: 3.9 W SWR: 1.08 What do you see there? Maybe next to Transmitter you see "SWR Protect"?
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va3rr
Joe AI5DD
Donald S Brant Jr
John Dusek
Daniel Conklin