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QMX Frequency Offset?

 

Last night I attempted to chase a few POTA ops with CW my QMX Low Band, version _023.? I noticed that the dial frequency on my QMX to be 1500 Hz higher at 7.048 than the posted frequency on the pota.app web page at 7.0465. Curious, I got out my 40M QCX-mini, which has been calibrated with GPS,? and found the posted frequency to be accurate.
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Before I attempt to deduce the TXCO offset to bring things into order, I'd like to ask if:
a) is this a result of some configuration?
b) has anyone had such a major offset with the TCXO? Seems very unlikely to me.
c) it's curious that the offset is 1500Hz - the WSPR offset
d) has this been introduced somehow in ver _023??
?
The QMX is set with an out-of-the-box ver _023 configuration except:
1. The Audio/ CW Filter has been changed to 300Hz @ 700Hz?? and the Auto-offset/tone has been set to Yes;? and
2. Sideband has been changed to LSB
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I have not attempted a re-install of an older version and did not notice any such frequency offset before now.
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Ideas anyone?
?
73/72
Steve W6WU
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Hi steve,
Same here on qmx plus. Changed sideband agn to usb and it works.
72 de wolf, DK1HW
 

Wolf,
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Thanks for the reply. I only switched to LSB to try? it, no problem to switch it back to USB. Very low priority bug for me since I operate CW.
?
@Hans - maybe consider looking at this bug while doing the SSB development?
?
73/72
Steve
 

Hi,
No such issue here tested on my QMX+ (FW .023) on 18MHz.
CW mode, switched from USB to LSB and back. The displayed frequency and the actual TX frequency was always the correct (the same).
Just guessing: the offset you mentioned is perhaps 2 times the side tone? 2 x 700Hz = 1400Hz. This issue was present some time ago.
--
73 Bojan S53DZ
 

On Mon, Aug 5, 2024 at 11:03 AM, Steve G4EDG wrote:
Hi Steve
?
I like to use LSB for CW too (rising tone as you tune HF).
Setting CW-R to ON should sort this out in one operation
?
The CW-R facility is not working properly (yet) and appears to do nothing receive wise when it is set to ON, however the transmit frequency is shifted, in order to have the receive side of things working correctly, LSB must be selected. Its telling that the offset is 2 x the sidetone frequency.
?
This is all a bit of a pain if you then want to operate in digi mode, where you will have to select USB.....CW-R can be left on.
?
Give it a try and? let me know how you get on.
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73 Steve G4EDG
 

Steve G4EDG,
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Yes, CW-R with LSB displays the frequency correctly.
?
The operation that I thought would happen in CW Mode is that setting the sideband without changing to CW-R would be of no effect to the displayed frequency.? CW, of course, is neither transmitted on one sideband or the other and it is the receiver LO that is offset on a sideband to produce the desired audio tone; leaving the frequency displayed on the carrier.? I thought selecting LSB would have offset the the receiver by the amount of the currently selected filter /tone on that sideband leaving the displayed frequency on the carrier. However, it seems that this software implementation does not (currently).
?
Having said all that, this is not a deal breaker for me as I only need CW to work properly and have set the Sideband back to the default USB. My curiosity in exploring the features led down this path. However in the future is would be nice to have this sorted out in a proper way - whatever that is.
?
73,
Steve W6WU
?
 

Hello Steve & Steve

So I'm a little confused... what do I need to do in the firmware, to make this work properly??

73 Hans G0UPL



On Tue, Aug 6, 2024 at 4:17?PM Steve W6WU via <w6wu.ars=[email protected]> wrote:
Steve G4EDG,
?
Yes, CW-R with LSB displays the frequency correctly.
?
The operation that I thought would happen in CW Mode is that setting the sideband without changing to CW-R would be of no effect to the displayed frequency.? CW, of course, is neither transmitted on one sideband or the other and it is the receiver LO that is offset on a sideband to produce the desired audio tone; leaving the frequency displayed on the carrier.? I thought selecting LSB would have offset the the receiver by the amount of the currently selected filter /tone on that sideband leaving the displayed frequency on the carrier. However, it seems that this software implementation does not (currently).
?
Having said all that, this is not a deal breaker for me as I only need CW to work properly and have set the Sideband back to the default USB. My curiosity in exploring the features led down this path. However in the future is would be nice to have this sorted out in a proper way - whatever that is.
?
73,
Steve W6WU
?
 

Hi Hans, thanks for looking into this.
?
On the QCX the CWR function determines if you are listening on LSB (CW-R ON) or USB (CW-R OFF), either setting the TX and RX are one the same frequency and a QSO can take place as verified using my FT1000mp as the QSO "partner" the only thing experienced differently on the QCX is the sense in which it tunes i.e. tone of signal rises as you tune HF (CW-R ON i.e. LSB) or tone of signal decreases as you tune HF (CW-R OFF i.e. USB). So everything is happy there...a very neat function.
?
On the QMX the CW-R and USB/LSB settings seem to interact.
?
The combinations that result in a situation where is QSO can take place are:
?
CW-R ON and LSB and
?
CW-R OFF and USB ON
?
The remaining combinations do not result in a situation where a QSO can take place:
?
CW-R ON and USB (QMX must be tuned to 14.058.92 to hear the 14.060.00 signal transmitted by my FT1000mp)
?
CW-R OFF and LSB (QMX must be tuned to 14.061.02 to hear the 14.060.00 signal transmitted by my FT1000mp)
?
The above were judged by ear, but is interesting that the frequency difference is twice my preferred listening tone...550Hz ish.
?
My understanding (and preference!) of the QMX CW-R function is that it is purely for CW, and that the USB/LSB choice is for Digi/SSB only...in this way the invalid combinations could be prevented and custom settings for each mode can be made "set and forget" thus negating the need to change menu settings when a mode change is made.
?
So what's to be done you ask? I would say when CW-R is ON, LSB must be selected automatically and in CW-R is OFF USB must be selected automatically. These USB/LSB selections should be overridden when in Digi mode and USB/LSB selection is the user defined value.
?
I must admit I haven't checked if CW-R ON or OFF affects Digi modes in a similar way...if so it could be sorted in a similar way to the above
?
I hope this makes sense! and explains why some users may not be getting many answers to their calls as their transmit frequency is off by over 1kHz.
?
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Steve G4EDG
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On Tue, Aug 6, 2024 at 10:37 AM, Steve G4EDG wrote:
So what's to be done you ask? I would say when CW-R is ON, LSB must be selected automatically and [when] CW-R is OFF USB must be selected automatically. These USB/LSB selections should be overridden when in Digi mode and USB/LSB selection is the user defined value.
Slight correction, sorry.
?
73 Steve G4EDG
?
 

Hello Steve

Thanks?for the comprehensive explanation, I understand (I think, anyway). I have corrected it in the latest firmware version 1_00_025 which I released just now. Please check and see if it is all correct now.?

73 Hans G0UPL



On Tue, Aug 6, 2024 at 8:37?PM Steve G4EDG via <g4edg=[email protected]> wrote:
Hi Hans, thanks for looking into this.
?
On the QCX the CWR function determines if you are listening on LSB (CW-R ON) or USB (CW-R OFF), either setting the TX and RX are one the same frequency and a QSO can take place as verified using my FT1000mp as the QSO "partner" the only thing experienced differently on the QCX is the sense in which it tunes i.e. tone of signal rises as you tune HF (CW-R ON i.e. LSB) or tone of signal decreases as you tune HF (CW-R OFF i.e. USB). So everything is happy there...a very neat function.
?
On the QMX the CW-R and USB/LSB settings seem to interact.
?
The combinations that result in a situation where is QSO can take place are:
?
CW-R ON and LSB and
?
CW-R OFF and USB ON
?
The remaining combinations do not result in a situation where a QSO can take place:
?
CW-R ON and USB (QMX must be tuned to 14.058.92 to hear the 14.060.00 signal transmitted by my FT1000mp)
?
CW-R OFF and LSB (QMX must be tuned to 14.061.02 to hear the 14.060.00 signal transmitted by my FT1000mp)
?
The above were judged by ear, but is interesting that the frequency difference is twice my preferred listening tone...550Hz ish.
?
My understanding (and preference!) of the QMX CW-R function is that it is purely for CW, and that the USB/LSB choice is for Digi/SSB only...in this way the invalid combinations could be prevented and custom settings for each mode can be made "set and forget" thus negating the need to change menu settings when a mode change is made.
?
So what's to be done you ask? I would say when CW-R is ON, LSB must be selected automatically and in CW-R is OFF USB must be selected automatically. These USB/LSB selections should be overridden when in Digi mode and USB/LSB selection is the user defined value.
?
I must admit I haven't checked if CW-R ON or OFF affects Digi modes in a similar way...if so it could be sorted in a similar way to the above
?
I hope this makes sense! and explains why some users may not be getting many answers to their calls as their transmit frequency is off by over 1kHz.
?
?
?
Steve G4EDG
?
?
?
?
?
?
?
?
?
?
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Evening Hans
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Thanks for the incredibly fast turn around on solving this problem....Ive checked it out using all combinations of CW-R and USB/LSB and all functions as expected. I'll try Digi tomorrow just to make sure.
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Well done on the filters too, Ive selected 200, 300 and 500 at 550Hz....so there isn't the small step in tone....3 filters at this sort of bandwidth is enough for me! I wonder if you can use the upcoming SSB filter for CW? It would be great to have this added to the CW filter menu, assuming the centre frequency can be set to around 550Hz +/- The filter shape factor is so good, tuning the band with a 500Hz filter is hard work!
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I put the QMX+ through its paces on Saturday during the European HF Championship contest, there were some huge signals and was able to pull out weak signals between these quite easily...the RX showed no signs of crumpling...a receiver up there with the best...well done!
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73 Steve G4EDG
 

Steve and Hans,
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Wow! Thank you both, Steve G4EDG for the thorough explanation of the issue; Hans for addressing this so quickly; and Steve once again for verifying the update. I'm off now to load to gleefully load version 1_00_025 in both of my QMX's!
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73,
Steve W6WU
 

Hi Steve
?
Evening Hans

Good morning. Sunrise right now at QRP Labs HQ here in Summers' Towers (see attached);?+26C local and rising to?+37 midday.
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Well done on the filters too, Ive selected 200, 300 and 500 at 550Hz....so there isn't the small step in tone....3 filters at this sort of bandwidth is enough for me! I wonder if you can use the upcoming SSB filter for CW? It would be great to have this added to the CW filter menu, assuming the centre frequency can be set to around 550Hz +/- The filter shape factor is so good, tuning the band with a 500Hz filter is hard work!

At the moment you have the "None" selection which means the current Digi filter with passband 150-3200Hz. Later I will add more filters too. For now I just implemented what I already had coded up, since the main priority is the SSB work.?

73 Hans G0UPL

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