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Thank you!

I would like to purchase an assembled (working) 10 watt linear hf amplifier.

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Thanks,

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AC4OW, Sam

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I have ordered a low pass filer from eBay:

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Assembled 12v 100W 3.5Mhz-30Mhz HF power amplifier low pass filter LPF Kit

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Thanks again!

Also do you have the internal GPS? if so unplug it.

Also is it in a case? If so remove it.?

On Tue, Apr 1, 2025 at 07:54 PM, Michael Shiplet wrote:

However, the measured voltage across R105 went from ~3V (normal operation) to ~4V (frozen)

Michael, where did you connect the GND probe of your Meter to the QMX GND?

3 V ... 3.3 V would be ok. This signal comes direct from a controller I/O-pin and the controller runs from VDD 3.3 V. 4 V is wrong. Maybe VDD is going wrong after a few minutes. This would be dangerous for some IC especially the controller. Could you measure VDD. You may use JP105 to contact VDD. But TAKE CARE not to connect VDD to "+12V". This would destroy some important elements.

Could you measure the supply current from the beginning until the QMX stops?

Could you check temperature of IC101? But please take care it could be hot.

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I would avoid to transmit in the moment.

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73 Ludwig

Also replug the front panel and look at the display connection and while it's out check for a tiny bridge or a whisker that may be in there. That will answer a lot of questions before real assistance comes!

Alright, did the reset, correctly selected the QMX+ version from initial selection, and had about 2 minutes of solid listening time to a QSO on 20m. Thought maybe the reset was going to fix it until I went into the menu to change my keyer setting and it froze on me ?

Will try doing a reset next.

Just tried it - the board gave me enough uptime that I could send a few dahs. It looks like I'm barely putting out any power, but I did see the FWD meter on my ATU bump a little bit. I didn't wait long enough for the radio to freeze out though, so I was at least able to give it a gentle shutdown this time ?

Also is there time to do a reset before the pro analysts see this post? That will give you a headstart! I did notice a little quirky behavior on mine, right after I first powered it up.?

Do you have enough time to transmit into a dummy load on 20?? Does it kick out, immediately??

I have a rev.3 I didn't burn in yet. So let me see if it is working HiHi. You made me think ??

That pulsing signal like CW is what I get too, so I don't think it's external. It doesn't change with tuning, so it seems like something getting injected into the audio.

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73, Dan - W2DLC

Hi George,

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The 12V power source is a 6000mAh Talentcell rechargeable battery. To connect power to the radio, I'm using the included DC plug that I got as part of my kit, which I've joined to one of the barrel connector wires that came with the battery. So the battery's barrel connector connects to the battery, and the QMX+'s barrel connector connects to the QMX+.

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For the 9V, I just used an off-the-shelf 9V battery with a 9V battery-clip-to-2.1mm-x-5.5mm barrel plug.

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73,

Michael

N7WTM

Hi Michael,

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Please describe the power source in detail.?

Including DC plug.?

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73,

George?

K3GK

I finished my QMX+ kit 2 weeks ago.? I built it for 9V, and held my breath as I powered it up for the first time.? ?Everything seems to work fine, and all bands receive and transmit.? I called CQ a few times on CW and saw typical results on the reverse beacon network.? ?I have also worked some FT8 on various bands.? ?So overall, I feel like it is a successful build.? ?That being said, I do have a question about the power output.? ?Running into a dummy load, I get the output as listed below.? ?Are these figures typical on the higher bands, and if not is there anything I can do to help increase the output to where it should be?

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73, Jim (w8ykg)

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160M? 5 Watts
80M ? ?5 Watts
60M ? ?5 Watts
40M ? ?4 Watts
30M ? ?4 Watts
20M ? ?3.5 Watts
17M ? ?3 Watts
15M ? ?3 Watts
12M ? ?3 Watts
10M ? ?2 Watts
6M? ? ? 1 Watt

I tracked it down with a portable radio with shortwave with a signal level indicator (a must).? It was not easy since the RFI was coupled into the power lines and shrewd up many houses away.? The power lines acted as great complex antenna that masked the direction of the source.

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If your problem is from a charger it may be turning on for short periods to top up a battery.?

Thank you for reply, now to figure out where is it ? it will be hard since it shows once in a while and it lasts 3-5 minutes

I think it can be corrected with filters or settings somehow. When I change to DIGI mode on the QMX, a lot of these noises disappear. In the image below, the bottom portion was DIGI, the top portion USB on the QMX+ (Pressed the Mode button just as green line appeared to change to USB RX)

Whatever filtering or settings are different between USB and DIGI, the RX looks a LOT better in DIGI. Notice the lines at 750, 1250, 1750, 2250, 2750 are non-existent in DIGI. The lines at 500,1000,1500,2000,2500,3000 appear unchanged by this, but there is definately something different between RX in DIGI and USB.

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In this picture, I cycle back through USB to LSB. The bottom half is USB, the top is LSB.

Notice that when I switch between USB and LSB the tone or noise at 1500 and 3k both become more pronounced (stronger signal indicated by line turning red instead of yellow) Also the lines at 500 and 250 get stronger (solid yellow instead of broken yellow). Earlier today the LSB side was showing a pulsing tone at 750 almost like carrier from CW, but not in any CW pattern.. I did not get a screen shot of that while it was happening, but I now suspect it may have been an external signal. Note that all these signals I am highlighting are with the radio connected to a dummy load with a 36" piece of RG-8x

Solved. Q502 was missing.