Hi all
General:?
Please be patient... this is a new rig, and we have yet to accumulate?collective trouble-shooting experience. I have just had a nice QSO with Earl 4Z4TJ on JS8Call, 5W QDX at both ends, on 40m. I also copied Earl on 20m WSPR yesterday. My QDX has been working faultlessly all weekend. I logged in to my PC remotely from my mobile phone and had many QSOs around Europe on FT8 on 20m and 40m, as well as working Muhsin TA1MHS on FT4, FT8 and JS8Call on Saturday. Even middle of the night last night I woke up and couldn't get back to sleep... went downstairs and sat on the sofa operating FT8 for an hour on 40m. That put me to sleep :-)?
The rig works and is reliable. Nevertheless we are now nearly 500 people building it at once, and some problems are going to arise, and we will need to build up some collective experience with operating and troubleshooting, this is normal. So please nobody be disappointed. There are a growing group of us with working QDX, even making QDX-to-QDX QSOs. So be patient we'll all get there.?
Firmware
Please do make sure you are on the latest firmware. We need to have a common reference point and not introduce more unknowns into the equation.?
No transmit power due to assembly faults
There are many possible reasons for this.?
1. Low Pass Filter toroid connection problems; this should be identifiable with a DMM in continuity mode. But even if it shows continuity during your test, this is not a 100% guarantee that all is well - if you have an intermittent connection, you could "pass" the DMM test but fail power transmission when you turn the board over, for example. If you have low pass filter toroid wire issues (enamel not burned/scraped off), this could also cause low receive signal strength.?
2. Another cause of failure to receive well can be soldering issues on the receive signal path: the large T50-2 band pass filter toroid L12, or the receive mixer phase splitter trifilar transformer T2. In the case of T2, you have not just wire enamel issues to consider, but also, did you get all the 6 wires in the correct 6 holes.?
3. If receive is working OK, but transmit has no power output, this points the finger at the output transformer or the T1 output transformer, or L14 choke. Again enamel on wires. Or in the case of T1, there could be shorts between winding caused by nicks to the enamel.?
4. Another possibility is issues in the band switching. There are four through-hole inductors, that have to be installed by removing the SMD inductors, as per the manual. If there are any mistakes here, then the corresponding band low pass filter cannot be switched into the circuit and you will get no power output on that band (as well as reduced receiver sensitivity).?
No transmit power due to configuration issues
Now if your radio is assembled properly, you can STILL have no transmit.?
An easy mistake to make, is to improperly configure WSJT-X on the "Radio" setting screen. By default, QDX VOX (Voice Operated Transmit) is disabled. Therefore CAT on WSJT-X must be properly configured, selecting Kenwood TS-440S as the CAT protocol. But you must also set up PTT method as CAT. The default in WSJT-X and JS8Call is VOX.?
If your QDX has VOX disabled, but the PTT Method set up in WSJT-X is VOX, then the PC will produce the correct sounds but QDX will just ignore them and not commence transmission.?
Of course you have to have selected the QDX sound card in the Audio setting too... and who knows, maybe in Windows there are other details to take care of in the audio settings. Same applies to Linux.?
If on the other hand, you enable VOX on the QDX, then it is easy to mistakenly send PC sounds to the QDX and enable the transmitter when you do not intend to do so. So CAT control of PTT is preferable.?
Dropped USB connections
If you suffer dropped USB connections - then I cannot rule out firmware bugs, they may be found - but a very definite possibility is common mode feedline current issues (RF in shack). On Friday when I had just put up the antenna at the new QTH I had this problem (the antenna orientation is not very ideal). Every time I put the radio into transmit, the USB connection got dropped. That was solved with a feedline choke consisting of 10 turns coax around an FT240-43 ferrite core. After that all the problems disappeared.?
It is also worth noting that a shorter USB cable could help, or clip-on ferrite on the USB cable.?
RF problems, grounding problems, all are very real and I think underestimated by many radio amateurs. Maybe you think you have a good ground. Maybe you even drove into the actual soil, a big copper rod. Still if your shack is upstairs, then shack ground will be several meters above the real ground, and several meters cannot be ignored even at HF!?
A tuner? 1.05 : 1 SWR? Yes but SWR does not prevent feedline problems either. Many people put a tuner in the shack between them and their coax feedline. But actually what you are now tuning is your antenna?+ feedline combination. Now since your coax is effectively now actually part of your antenna, you could have a significant RF right there brought into your shack.?
So a lot of problems can and do occur, and can be different with different radios, or different power supplies... and yet are not the fault of the radio.?
By "dropped USB connections" that can mean the audio connection and/or the serial data connection.?
Transmitting?out of band
Remember also that if you try to transmit on bands or frequencies below 80m, or above 20m, then QDX will just refuse. In that case the LED will not start flashing.?
Please transmit at full volume
Never use the slider on the right hand side of the WSKJ-X window, to try to reduce output power. This has NO effect on the QDX except to reduce the accuracy of the audio frequency measurement. The same applies to any gain settings in your audio settings on your machine. There is NO POINT AT ALL to running WSJT-X at anything other than full volume.?
"TX" signal and "RX" signal
These two signals are not automatically complimentary.?
When the radio is switched from Receive to Transmit, the RX signal will go low. During Receive, it will go high.?
The TX signal is more accurately a Key-down signal.?
Now the RX signal will go low, when the radio is switched into transmit state by the appropriate CAT command from WSJT-X. However the TX signal will not go high, until valid audio is detected and measured. Only at that point, will QDX activate the TX signal (put it high i.e. 3.3V).?
In order to get TX high, two conditions are necessary (assuming VOX is disabled, and WSJT-X is set up for PTT Method: CAT):
a) The radio must have been placed into transmit mode by receiving a CAT Command?
b) The radio must receive audio from WSJT-X and measure it properly; so WSJT-X must be sending audio to the QDX USB emulated sound card correctly (WSJT-X configuration, any other sound configurations on your PC).?
5V tolerant pins...?
To avoid introducing too much info to this thread, Fred W0FMS, I am going to reply separately to lay this one to rest.?
73 Hans G0UPL
Bob Benedict, KD8CGH
David Wilcox K8WPE