Hi all,

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just finished my QDX (high bands version) build and measured the output power of all bands:

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20m: 4.6W
17m: 4.9W
15m: 2.4W
12m: 3.5W
10m: 3.5W

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After reading I am a bit confused why there is significantly less power on 15m than on 17m as they share an LPF.

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Any suggestions for further testing/tweaking?

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73

Michael, DK1MI/N1BSD

On Tue, Aug 6, 2024 at 02:06 PM, Hans Summers wrote:

The original filters plus the combination filter pairs produce a total of 54 different filters as follows:

• Passband 50? ?Centers 625, 675, 725, 775, 825
• Passband 100? Centers 600, 650, 600, 750, 800, 850
• Passband 150? Centers 575, 625, 675, 725, 775, 825, 875
• Passband 200? Centers 550, 600, 650, 700, 750, 800, 850, 900
• Passband 250? Centers 525, 575, 625, 675, 725, 775, 825, 875, 925
• Passband 300? Centers 500, 550, 600, 650, 700, 750, 800, 850, 900, 950
• Passband 400? Centers 600, 700, 800, 900
• Passband 500? Centers 550, 650, 750, 850, 950

I also added a new sub-menu screen which allows the 8 passbands to be disabled/enabled from the CW passband selection, and in this way you can, if you wish, make sure that only filters are available which match your choice of Sidetone / CW Offset frequency.?

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Love those narrow filters.

Hans, just a cosmetic one - the filters were originally disabled after upgrade (v23->v25). I had to enable them one by one. Not a big deal at all, just wonder whether it was intended or something you might want to alter.

Thanks!

Everything is a compromise in engineering and everything extracts a price. I rarely bother if my antenna is below 2:1 for all sorts of reasons, such as tuning range over several bands, height above ground etc.

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https://www.wearecb.com/what-is-swr.html#:~:text=The%20radio%20will%20receive%20and,or%20less%20across%20all%20channels.

Hi Ludwig

Thank you for your help.? I have been away for a few weeks but now back and with a new probe.? However the new probe didn't tell me anything more that I had already found BUT I did find IC503 (74ACT08D) had slightly different output levels to the FET gates (along with the weird waveform).? I replaced the IC and now have power output on all bands!? The drive waveform to the gates is now much better.? I'm going to look at the filters now and fiddle with the toroids to see if I can get a more consistent output across the bands.

Now there is just the insensitive receiver.? I can read signals from 3uV upwards but the audio is quite noisy.? The 3uV level is consistent across all bands so it is something common after the filtering.? I tried a linear power supply but it made no difference.

Regards & thank you again.

Greg

well done Scotty such a short distance on 6 m is not easy. I am waiting for my QMX to find the fault but have a Flexradio 1500 on 6 m and mostly the skips were for larger distances. Make yourself a simple diamond antenna on a fibre pole. thats quick and easy. Look for the Rhombic Loop

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Martin

DK3UW

The PTT mod is simply to make PTT switching work when PTT switching is set to ground.

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It is mainly for when using an external amplifier to key that when sending.?

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I'd forgotten about this and wondered why my OG rev1 QMX was not keying my Tokyo Hy-Power HL-50B.?

Has screen colors?

I have not made the PTT modification yet on my QMX.

Right now of course it works perfectly on CW and ft8.

it’s not clear to me what the actual lack of functionality is.

Would ?something like a microphone not work when SSB is implemented?

I know this is a simple modification which I will do and I’m just looking for clarification… Thank you all.

I found some very inexpensive voltage regulators that will reduce the higher DC voltage to what ever you want it to be. They are rated for 3 Amps.

So getting 9 or 12 volts DC from that LiFePo battery is easy.

On Amazon they are listed as:

That is fantastic Zhenxing .? I have just ordered the CMX+ (as soon as the 1900Z CWT ended!).? I'm looking forward to the build and joining you all in playing with this radio.

I had to enable the filters one by one in the Audio/CW Filters/Choose Filters menu before they became available to select. Not sure if that helps anyone.

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73

Simon

Hi Zhenxing,

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I got your extio DLL file working on N1MM Logger+ with QMX+ v.25 and it is very interesting. This is getting exciting to me because I find it tedious to manually tune the VFO knob to search the spectrum for CW signals when they are sparse. I do see an offset when I click on the identified CW signal and I suppose this is as you mention (I am not using 700Hz).?

Anyway, awesome work and I look forward to being able to control the offset when clicking on an identified CW signal.

73! -Gregg?
W7GRM

On Thu, Aug 8, 2024 at 12:04 AM, @Ludwig_DH8WN wrote:

Do you find a "P" (practice mode) or a "S" (SWR protection) in the first row of the display?

Jon, whats with a "S"? Maybe your antenna has more than SWR 3 and the SWR protection kicked in?

(Resonant doesn't mean a low SWR in all cases.)

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Which current when sending?

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73 Ludwig

This is the procedure I use....

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Hi Ludwig,

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Thank you for the very quick response!

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Below are the configurations set for the radio.

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I don't have a dummy load on hand and assumed, probably poorly, that using a resonant antenna would suffice.

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-Jon

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All,

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???? I built my QMX+ as a 9V device; I frequently run field equipment from 6-packs of NiMH rechargeable batteries at 7.2V nominal.? This had me concerned about being able to also run it from my 13.8VDC home supply as I'd also like to run it from my "winter" location in the attached garage.? That fact, coupled with the fact that I got a flaky DC input jack on my QMX+, and I prefer to use Anderson Power Poles whenever possible for power connections, forced me to seek solutions. ??

???? I started out trying to switch MOSFETS using a zener diode to switch between either directly tying input to the rig when input V was below 9V, or switching that input power to a LM317 when it went higher than 9V, but that circuit didn't work very well.

??? Then I looked into LDO regulators that would regulate my input voltage to 9V whenever it exceeded 9V, and reduced it only slightly when below 9V.? As luck would have it, I had samples of Linear Technologies LT3086 LDO regulators in my junque box, so I built up a new rear plate for my rig sans the coaxial DC input and the unused QLG3 jack.? This plate has a pair of Anderson Power Poles for DC input, and acts as the heatsink for the LDO regulator.? I then whipped up a tiny PCB and mounted it (and the tab of the regulator) to the new plate.

??? As built, it outputs 7.9V as I tested it at 7.5V and fear blowing the finals in field operation.

???? I then added a 4-pin socket to the main PCB immediately behind the coaxial jack to use to insert the DC from the new regulator.? I left the Main PCB totally intact so I can revert to using the original rear plate if I need to.

???? When receiving, the LDO drops less than 50mV.? When transmitting, it drops about 250mV.? Much less than a typical diode, and enough loss for me to be satisfied.

???? Pix of the modifications are attached and schematics/PCB layouts are available on request.

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W2EB

Bill Lazure

East Syracuse, NY USA

Jon,

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could you show these values, connecting a dummy load to the QMX:

- Output, measured external

- Supply current when sending

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Do you find a "P" (practice mode) or a "S" (SWR protection) in the first row of the display?

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73 Ludwig

I discovered that running the following command in a Mac Terminal works really well to get into the QMX+ terminal, instead of installing PuTTY or another shell client. Sharing for other Mac users that may find this helpful.

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"screen" is the application/command

tty.usbmodem2101 is what my device is called (discovered by going into /dev and running "ls" command)

9600 is the baud rate

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screen tty.usbmodem2101 9600

I recently finished building my QMX+ and all the testing and diagnostics seem to be working well. I also hooked up an EFHW antenna and was able to receive CW on multiple bands.

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However, I went into terminal and ran some diagnostics and on every band I get a power reading of 0.0W and no SWR return even with a resonant 30M EFHW attached. Should I be concerned? I would've expected a power level to be read here.

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Thanks!

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-Jon

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