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A number of times I've had the situation in digital mode where the QMX is not transmitting as expected. I immediately get concerned that something is blown. The last time this happened I connected a dummy load and went to the diagnostic screen in terminal mode and still no transmit. Only then did I think, oh, maybe transmit lockout. Sure enough, cycle the power and its back working again. I wish there was some indication on the screen for transmit lockout. I've blown so many finals in the QCX and QDX that my first thought is always something has failed.? |
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Hello ?
Are you running the latest firmware? In the latest firmware, in the diagnostic screen there's a reason indicated, above the transmitter testing section in the bottom right, whenever transmitting is not occurring. It can be things like the VFO is outside a defined band (and TX outside band limits is disabled); or TX is disabled on the band you are on. Most common is that SWR protection?has been triggered, which would be indicated by an 'S' on the screen.? I don't know of any situation where the radio can be locked from transmitting but there is no displayed indication of why.? 73 Hans G0UPL |
开云体育In addition, I discovered almost immediately that too much audio
drive into the radio for digital modes will inhibit transmit.? I
thought something was wrong with my QMX when it wouldn't transmit
but for a brief second, but when I turned down the audio drive to
100% (Linux pavumixer) it behaved normally.? Presumably it can
overwhelm the ADC.? The audio was turned up for another
application but the laptop thought it applied to the QMX as well. 73 Charles - NK8O On 1/13/25 07:10, Hans Summers via
groups.io wrote:
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Hello Charles
There is no ADC involved. All transfer from the PC to the QMX is digital via the USB audio sound card emulation of QMX. So what happens if you have a sinewave at full 100.0% volume, the sinewave peaks and troughs hit the peak numbers the digital transfer is capable of. If you go beyond that, then the peaks "wrap around" so you then get a frequency component at even harmonics, at a lower amplitude; QMX will then measure the incorrect frequency, as well as determine that the amplitude (of those wrapped peaks) is below the threshold and it will switch off the transmit.? It's all correct behaviour of QMX.? 73 Hans G0UPL |
开云体育Hans, Thank you for your excellent explanation!? I wasn't worried about
it at all, it was just a discovery as I was investigating CW works
perfectly but digital was being squirrlly.? I've seen other
comments about this but no one had a reason.? Just user error, as
is typically the case. Other than tweaking the low pass
filters on a few bands, I have not much left to do on this QMX.? I
have been on the air and made quite a few FT8 contacts with a
little over 3 watts out, and some surprising CW contact.? The next
challenge will be to try it out in a rapid-fire WWFF activation
with a pile-up, but I'm beginning to think this might become a
regular in my park activation line-up.? It's like a lot of
things.? I worry a lot less about a $150 radio than gets the job
done than my very expensive KX2 & KX3, and others in the
cadre.? It cost less than my first QRP rig in 2011, and performs
rings around that radio.
72
Charles - NK8O
On 1/13/25 10:29, Hans Summers via
groups.io wrote:
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