I finished mine yesterday an I had about 25 QSOs on 40 and 30 m (40m with Dipole, 30m with lw). Than I changed to 20m (Magnetic Loop..... I tuned the Loop before with my TS940 got get the resonance frequenzy, good SWR) . Also 5 Watts with about 13V. Than.after 10 times calling CQ.......Smoke. I burned two BS170. I substituted all 4. I can receive , and I hear the Transmission with my TS940, but no Power at the output behind the low passes.
I made a measurement directly at the Transistors. with the RF probe (thanks to George Dobbs :)? ). 40V, about 4Watts. Seams to bee, that the new Transistors are working. But no Power to the Antenna Socket. Something destroyed within the Power line... :( . Any Idea ? I never made anything with SMD. First time for me was the replacement of the 47?H. But it worked well.
Maybe C34 damaged ?And as a result, no power arrives the low passes ?
73 de Matt , DL1SER

?

Hello Bob,

Congratulations on your 40 meters success.? This does indicate that the build is most likely OK.? Hans Summers has written a post that describes what some of the causes might be for low or no power output.
/g/QRPLabs/message/74132

Based on your symptoms, I would suspect that the USB audio connection is being interfered with.? Look at the?"TX" signal and "RX" signal?section of the post.??

Note that there are two conditions to get power out as stated in the post.? The one is being met: The CAT command to set the rig in transmit mode is being received.? I suspect the other one, a valid tone from the PC, is not.? The most likely cause of this is that there is RF blocking the USB audio when it first keys up and quickly knocks out the USB connection for long enough to drop out the TX signal.? The CAt command is still active, so it appears to be in transmit mode.? This is supported by the current draw NOT going high as it does on 40 meters.? One possible way to verify might be to try transmitting into a shielded dummy load and see if you get power on all bands.

Hans indicated steps to take to address this issue.? My suggestion is snap-on ferrites, as that worked for me with my other RF-sensitive rig to computer connection.? In trying to find out the cause of my low power issue I have blown the BS170s and need to replace them before I can verify that the ferrites work for me with the QDX.

Out of curiosity, what are you using for an antenna?

Good luck and happy hunting (for the bug).
73
Evan
AC9TU

Hi,

Nov. 8 update:

My QDX order did not move since October 31st… 9 days since the last update…. still stuck at Grace-Hollogne. :-(

I called Fedex for an update. Because I am not the shipper, they cannot provide me information or the reason why my package is stuck there.

73

--
Jeff | VA2SS

I recently completed assembling my QDX and and updated the firmware. I have been testing it before stuffing it into its case. WSJT has no reported problem controlling the QDX. It receives on all four bands as expected. I wound T1 3:2, get 4.4 watts out with 12 volts power on 40 meters and have made several contacts. On the other three bands I can receive, and on selecting tune or transmission the led indicates transmission, but there is zero.zero watts power out. The current draw also does not increase from that of receive mode.
From the 40 meter Xmit I know the PA transistors are good. Since I don't see a higher current draw on Xmit on the other bands I assume it's not that the other LPFs are hosed. The led indicates transmission so the controller got the message and from 40 meters I know it can activate transmission. Any ideas what to test next?
--
? 73
??? KD8CGH

C34 , what happens, if this conductivity is crashed ?

Matt,

This takes the output from the PA to the LPFs. I see it is a SM device, position shown on page 33 of the manual. Might be worth a look.

Has anybody got a measurement of the Voltage (Output each BS170 while transmitting)? , that I can compare with ? Output of the BS170 Transistors? would be nice so get this Info. Than I know, that the substituted BS170 are doing the job. It?s so frustrating, 3 Day Work and having good first FT8 QSOs with that tiny device and than......:(.

If you are seeing 40 volts at T1 output with your probe then you should see some power out.
Looking at the schematic from T1 RF goes through C34 and on to switching diodes D4,5,6.
I am reluctant to suggest you use your probe to trace the output as the PA is producing power that is going nowhere. More damage could result.
That is why I suggested testing with as low a voltage as possible powering the QDX .

73 Alan G4ZFQ

I set up my QDX "exactly" as described by Hans in the manual and was also getting rig control errors from WSJT-X. It passed the CAT test, but asked to reconfigure when changing bands, tuning or transmitting.? It turned out that I missed the setting of Mode to none. I changed that and everything worked.
--
? 73
??? KD8CGH

L5/7/9 O.K. Alan, I?ll try. But they worked well before the crash. Each Band with full power.

C34 , what happens, if this conductivity is crashed ? I can receive without Problems and I can hear the FT8 Signal with my control TS940 beside in the shack (without an antenna). So , The transmission works, but no Power output . Iám not experienced with SMD soldering :(.
I was happy to get the four 47?H away from the board. :)

Has anybody got a measurement of the Voltage (Output each BS170 while transmitting)? , that I can compare with ? Output of the BS170 Transistors? would be nice so get this Info. Than I know, that the substituted BS170 are doing the job. It?s so frustrating, 3 Day Work and having good first FT8 QSOs with that tiny device and than......:(.

73 Matt, DL1SER

Hi Chris,
I am running wsjtx on a raspi 4 but to my QCX mini and use the CAT port \dev\ttyUSB0. This seems to work fine.

73/Ken g4apb

Sorry - thatt should've read Month KM6WT and Gregg W7GRM

开云体育

Mine worked well to finish the alignment of my Classic QCX.

The QRP Guys power/dummy load/SWR bridge device works well and I just used it to test my Classic QCX that I just completed. Excellent device.

Dave K8WPE

David J. Wilcox’s iPad

Thanks, Theo, for bringing this issue up again.? In February Hans acknowledged the matter and was going to look into it as soon as things settled down.? I've not seen or found any resolution as yet.

But in the thread you've so helpfully provided a link to, there're findings and suggestions by Mont Pierce KM6WT and Greg and me that point strongly to the source of the tone being the (next intended) Tx frequency signal at the Si5351 CLK2 pin out.? That might be checked further by removing the resistor in the path that feeds the CLK2 alignment signal to the antenna input. ? Mont and Greg (and maybe others) have suggested a firmware mod (move the Tx frequency well away from the Rx frequency during receive) as a fix.? If I'm right, removing that resistor (after alignment!) might also do the job.

I'm not going to mess with my mini any further - I very nearly killed it already with ham-fisted replacement of op amps!? (Hint: don't try that with lead-free solder)

73
Rod G0VKX

Hans,

Boa, you have still 3000 SMD inductors on stock... :o)

For the Rev 2 boards, do you plan to use the same SMD inductors ?
And during assembly they have to be removed and replaced by the
extra delivered through-hole ?

73's de OE1MWW
Wolfgang

I use a Raspberry Pi4 to run WSJT-X 2.5.0 with an IC-7300 and it’s fine.? So I transferred the USB cable to the QDX and set up a new configuration for QDX exactly as described by Hans in the manual.

I get a constant error message ‘ Rig Control Error – do you want to reconfigure the radio interface?’?

The good news is that something is working - WSJT-X recognises the QDX, hovering over the port information brings up ‘dev/ttyACM0?? QRP Labs QDX transceiver’ and it decodes FT8 on 30m and 40m.? But only after I managed to set FT8 and the band by clicking on ‘Retry’ and quickly trying to click on the mode and band menus before the amber spot turned back to red.? I’m not fast enough with a mouse to succeed more than maybe 1 in 10 attempts so it’s an exercise in frustration.??

On 30m, the message detail shows:

Hamlib error:? communication timed out

kenwood_open: no response from rig

kenwood.c(863): kenwood_open return (-5)?

rig.c(1026): rig_open return(-5) while opening connection to rig

?

However on 40m, the message detail shows:

Hamlib error:? Protocol error

kenwood_open: cannot get identification

kenwood.c(880): kenwood_open return (-8)

rig.c(1026) rig_open return(-8) while opening connection to rig

?

I tried selecting TS440S, TS480 and, for good measure, several of the other Kenwood HF rigs listed but no difference.

I have checked and resoldered the USB connector on the QDX board and it looks fine.? I have also tried a different USB cable.?

I should be most grateful for any suggestions as to how to resolve this issue.

Many thanks.

?

Chris? G4CWS

I get 40V with dhe RF probe (2x Voltage Peak of die Wave => about 4Watts). But no Sigs at the BNC connector anymore. Seams to be something destroyed between the P.A. and the low passes ? Any idea? I designed the QDX fpr 12V 3:2 Transformer.

Matthias,

When testing the PA I suggest powering the QDX with as low a voltage as possible, 7 volts or less, I'm not sure of the absolute minimum. Possibly as low as 5.5 volts, The regulators are specified 1 volt drop-out.

Check C34 and all soldered joints on LPF inductors.

Operation of the BPF selection can be checked on receive. Testing volts at L5, 7 or 9 should show low (0.6 volts?) on the selected band.

73 Alan G4ZFQ