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Low power on all bands, QDX high bands, assembled at factory

 

All measurements of power from a Daiwa meter (lowest range is 15W) via dummy load (very brief tests on antenna almost identical).
20M - 10M power out shows as 2.3-2.5W. I don't, however, think this is a radio problem, but instead I may not be getting enough audio "juice" into it.

I'm on Linux Ubuntu, Fldigi v.****.20 (which has the QDX/QCX hamlib file). The QDX shows up in portaudio devices for the system and in Fldigi. The Fldigi attenuator is at 0.0.
The Linux sound devices are the analog QDX ones. The input system volume control acts normally, that is the waterfall brightens or dims moving the slider.

However, there is not slider for the Output setting and fiddling with the overall system volume control has no effect.

So, in short, I think this is a software issue and as I'm not really a Linux whiz, maybe someone else can help me out figuring out if there is a way to boost the output audio, so I can at least see i that's the problem.

73,
Casey
 

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Study the manual on how the QDX works, and you will find that the audio level of the input has no effect on the power output. There is either enough audio to turn the transmitter on at full power, or there is not. ?While it is marginally better for frequency stability to turn the output all the way up (and drive a digital square wave into the radio), there is no output power control. Is it possible that the radio was built for 12 V and you are running it on 9 V?

73, Willie N1JBJ

On Aug 18, 2023, at 6:53 PM, Casey Bahr <hansva9@...> wrote:

?

All measurements of power from a Daiwa meter (lowest range is 15W) via dummy load (very brief tests on antenna almost identical).
20M - 10M power out shows as 2.3-2.5W. I don't, however, think this is a radio problem, but instead I may not be getting enough audio "juice" into it.

I'm on Linux Ubuntu, Fldigi v.****.20 (which has the QDX/QCX hamlib file). The QDX shows up in portaudio devices for the system and in Fldigi. The Fldigi attenuator is at 0.0.
The Linux sound devices are the analog QDX ones. The input system volume control acts normally, that is the waterfall brightens or dims moving the slider.

However, there is not slider for the Output setting and fiddling with the overall system volume control has no effect.

So, in short, I think this is a software issue and as I'm not really a Linux whiz, maybe someone else can help me out figuring out if there is a way to boost the output audio, so I can at least see i that's the problem.

73,
Casey
 

Yes, I know the input has no affect on the output, just noting that something is working between computer, software and rig.

It is built for 12V, currently running it at 11.8V, same behavior at 10V.

I now suspect the SWR meter is in error at the QRP level. I dug out my KX1, and to a dummy load, the rig says 4.0W out, but the SWR meter says 2W.

Nothing I can do about that. There's no calibration control on it.

tnx es 73,

Casey
 

¿ªÔÆÌåÓý

Casey,

If you have the Tx Attenuator set to zero in fldigi then that is the best you can do as far as audio into the QDX. Of course be sure your system mixer settings are set to 100% for input and output. My linux uses Pulse Audio so Pavucontrol is the name of the mixer. Alt+F2 and type pauvcontrol should bring it up if it's installed. If it's not installed install it "sudo apt-get install pavucontrol" . Some new versions of linux are moving to a different sound system that I know nothing about so can't help with that.

73,
Cliff, AE5ZA



On Aug 18, 2023, at 17:53, Casey Bahr <hansva9@...> wrote:

All measurements of power from a Daiwa meter (lowest range is 15W) via dummy load (very brief tests on antenna almost identical).
20M - 10M power out shows as 2.3-2.5W. I don't, however, think this is a radio problem, but instead I may not be getting enough audio "juice" into it.

I'm on Linux Ubuntu, Fldigi v.****.20 (which has the QDX/QCX hamlib file). The QDX shows up in portaudio devices for the system and in Fldigi. The Fldigi attenuator is at 0.0.
The Linux sound devices are the analog QDX ones. The input system volume control acts normally, that is the waterfall brightens or dims moving the slider.

However, there is not slider for the Output setting and fiddling with the overall system volume control has no effect.

So, in short, I think this is a software issue and as I'm not really a Linux whiz, maybe someone else can help me out figuring out if there is a way to boost the output audio, so I can at least see i that's the problem.

73,
Casey
 

Yes, it appears to be so. As Willie noted, once you get over the audio threshold (which it clearly does), it's full power out regardless.

I actually played with pavucontrol, btw, but the output was already set there at 153%.

I'm mostly convinced that the meter is wrong, since it also reports 2W from my KX1, whereas the KX1 reports 4.0W (at SWR 1:1). So, 2 x 2 is 4W, thus 2 x 2.5 from the QDX, should be just right.

So, I'll use it as-is and I am ordering an RF probe kit for my multimeter, which should settle the question. Nice tool to have anyway.

73,

Casey
 

Just to tie this one off ... I acquired an RF Probe kit from QRP Kits, assembled it and applied it.
My CN-501H SWR meter does indeed read low for my two QRP radios, but not by much actually. It displays 2.2W and the RF power calc is 2.9W with the probe (at 11.8VDC input). Filed under "good to know".
?
73,

Casey

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