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Re: QMX display unususal problem #qmx #dispay

 

Marek,

I'm not that knowledgeable either. But it seems to me the primary suspects would be the pins that interconnect the display to the main board. Both the socket and the pins. Are there good solder joints all around, no whiskers or other partial/sporadic shorts?

73 de Todd W2TEF
Re: Does the QMX need a mic preamp? #qmx #QMXplus #SSB Firmware beta 1_01_003 release #qmx #QMXplus #ssb

 

Hi Gary,
I eventually came to the conclusion that the QMX just didn't have enough 'juice' to drive the MAX9814 from the TRS terminal.
Thanks for confirming.
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Cheers.
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Mel. M0KMD
Re: #qmx #SSB Firmware beta 1_01_003 release #qmx #ssb

 

Hmmm... it has been working fine on the radios I updated to v1_01_003.
Is there a possibility that your power modulation circuit is broken?
For example Q507 shorted, so it can't change the transmit voltage?
Re: #qmx #SSB Firmware beta 1_01_003 release #qmx #ssb

 

Steve, please check Terminal - Diagnostics for the PA voltage in RX mode.
Maybe the amplitude modulator Q507 is broken. In this case you are able to TX but only with full power and without envelope shaping.
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73 Ludwig
Re: #qmx #SSB Firmware beta 1_01_003 release #qmx #ssb

 

Steve, in my experiments, I found that when setting the "Tune %" in the protection menu, you have to exit fully from the menu system for that setting to take effect. ?If I back out just one higher level and go to directly the Hardware test -> Tune SWR function, it does not take effect. ?But if I exit the menu system after changing "Tune %", it functions properly, and adjusts the Tune SWR power as expected (and also the SWR sweep power).
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That helps explain why the setting did not always update.? However, I am still having the issue that my QMX+ puts out full power regardless of the setting.
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--
Steve KA0SM
Re: PA mod for QMX+

 

The usual problem with (not entirely sure why) beefed up ?FETs is poor 10 metre performance
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Do you have any measurements ?for this Mod ??
QMX display unususal problem #qmx #dispay

 

Hi All,
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My mid band QMX Rev.2 developed display problem after 4-5 months of good working. Firmware 1_000_027 I build 12V version.
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After switching on all seems ok and works, but after 20-30sec display becomes corrupted. Initially it is just a few letters but soon after that all text is corrupted and gibberish.?
When I switch off and on top row is just black boxes.??
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If I leave radio switched off and detached from battery for day or so and switch it on problem repeats itself again. I mean first it works and then display problems start. I done this couple of times now and each time Initially it works and then after display stops to play a game.
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Connecting to computer through USB works and all diagnostics and LPF/SWR/etc... tests do not show anything unusual.
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Any ideas what's going on? I am not that knowledgeable to sort it out myself. Can you direct me what else I should check??
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---------------------------------
73 de Marek SP9TKW
Re: Tariffs?

 

All Han's needs to do is appoint an agent in Russia and ship via him.
Re: Does the QMX need a mic preamp? #qmx #QMXplus #SSB Firmware beta 1_01_003 release #qmx #QMXplus #ssb

 

Mel,
The MAX9814 tries to draw 3mA so it pulls the output of the QMX to near ground since 3mAx2.2k=6.6V when only 3.3 v is available
Gary
W9TD
Re: Too Much Power #qrp #cw #qmx

 

The diode drop technique is adequate for safety with “12v” batteries that are closer to 14v fully charged, but my goal is equalize the power as close to 5W as possible, across all bands when the supply is actually 12v.
Re: Too Much Power #qrp #cw #qmx

 

Battery measures 12v “key up” and sags to 10v - 11v on “key down” depending on band selection.
Re: QMX+ T507 winding direction?

 

Thanks Russ! Fortunately the Internet Archive's "Wayback Machine" has an archive of that page:
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Looks like a handy circuit. I may start using this in other projects.
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Re: #qmx mid-band receive #qmx #troubleshooting

 

Those scans look nice.? You have gained at least 6dB on 15 and 17 - maybe more.?
Now to test it in practice and see if you notice the change.
Yes, there is some other 'gain' factor going on; something attenuating the signal on 15/17 apart from the BP filter.? I wish I knew what it was.
Stan KC7XE
Re: QMX+ loose some characters while sending stored messages #qmx #QMXp #QMXplus #troubleshooting

 

hi, sorry, today I'm not able to test ... will inform you soon... tnx so long
Udo DF4BJ?
Re: Too Much Power #qrp #cw #qmx

 

A fully charged 12 V battery is definitely not 12V
Re: #qmx #SSB Firmware beta 1_01_003 release #qmx #ssb

 

On Wed, Apr 9, 2025 at 11:27 AM, Steve M wrote:
I am finding that the setting for the "Tune %" under the Protection menu has no effect on the power output when using the Tune SWR function under the Hardware tests.
Steve, in my experiments, I found that when setting the "Tune %" in the protection menu, you have to exit fully from the menu system for that setting to take effect.? If I back out just one higher level and go to directly the Hardware test -> Tune SWR function, it does not take effect.? But if I exit the menu system after changing "Tune %", it functions properly, and adjusts the Tune SWR power as expected (and also the SWR sweep power).
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Stan KC7XE
Re: Too Much Power #qrp #cw #qmx

 

开云体育

Hi Matt - just reduce your input voltage by adding some series diodes, rated at 2A or so.


Regards

Roger

8P6RX

On 09/04/2025 14:44, Matt - W6CSN via groups.io wrote:

The QMX mid-bander (60m thru 15m) is one of my primary radios for portable QRP operations for nearly a year now. The “problem” is that it puts out too much power in CW mode. Here are the numbers using a fully charged 12v battery into a 50 Ohm dummy load measured with an external watt meter:
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60m - 6.1W
40m - 5.3W
30m - 5.1W
20m - 5.6W
17m - 4.5W
15m - 6.5W
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QMX Firmware is 1.00.026
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Question; with the amplitude modulation capability that exists to provide SSB, can the CW mode be enhanced with per band configurations that enable trimming the power down to 5.0W for “by-the-book” QRP and to also lessen any risk to the hardware resulting from power levels that exceed 5 watts.
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I can also see a use case for an easily accessible CW power level “knob” for running QRPp without fiddling with the supply voltage.
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72,
Matt
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Re: Too Much Power #qrp #cw #qmx

 

The approach I used was adding a high current diode in the power line between the battery and the radio to drop the voltage and reduce the power output.
--
Steve KA0SM
Too Much Power #qrp #cw #qmx

 

The QMX mid-bander (60m thru 15m) is one of my primary radios for portable QRP operations for nearly a year now. The “problem” is that it puts out too much power in CW mode. Here are the numbers using a fully charged 12v battery into a 50 Ohm dummy load measured with an external watt meter:
?
60m - 6.1W
40m - 5.3W
30m - 5.1W
20m - 5.6W
17m - 4.5W
15m - 6.5W
?
QMX Firmware is 1.00.026
?
Question; with the amplitude modulation capability that exists to provide SSB, can the CW mode be enhanced with per band configurations that enable trimming the power down to 5.0W for “by-the-book” QRP and to also lessen any risk to the hardware resulting from power levels that exceed 5 watts.
?
I can also see a use case for an easily accessible CW power level “knob” for running QRPp without fiddling with the supply voltage.
?
72,
Matt
?
?
Re: #qmx #SSB Firmware beta 1_01_003 release #qmx #ssb

 

Possible Bug - I am not sure if this has been reported previously.? My apologies if this has already been discussed.

I am finding that the setting for the "Tune %" under the Protection menu has no effect on the power output when using the Tune SWR function under the Hardware tests.? I get 5 watts out regardless of the setting.? Also, if I change the protection setting, I will not see the change on the Tune SWR function until I do a power cycle.
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I have also seen the issue that Peter AI7YN reported with the frequency in the Tune SWR screen not always reflecting the frequency the VFO was tuned to prior to entering Tune SWR mode.
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--
Steve KA0SM
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