I assembled my QDX this week, built for a 9v supply. ?All went well, interfaced with WSJT-X v2.5.1 on Toshiba laptop running up-to-date Windows 10. ?In WSJT-X under settings, the Audio tab shows ¡°Digital Audio Interface (QDX Transceiver)¡± as present for both Input and Output, and selected. ?The Radio tab shows Rig as Kenwood TS-480, CAT Control over Serial Port COM3, and PTT method CAT. ?Test CAT works, Test PTT puts QDX into Transmit mode it appears, with the LED?triple light flash mode on the QDX. ?The receiver works fine on all four bands. ?BUT there is no RF output at all. ?Putting the QDX into transmit with Test PTT in the Radio tab, or Enable Tx, or Tune, causes the LED to flash, but no RF output. ?Scoping the unit out, I see no signal on the gates of the BS170 transistors. ?Examining IC5, the 74ACT08, I see CLK0 at pins 9 and12 and CLK1 at pins 1 and 4 both present at expected levels. BUT the Tx line is low in both Receive and Transmit modes. ?So the outputs on pins 8/11 and 3/6 are always low, thus no drive to the BS170s. Resistance checks on the Tx line with the QDX not powered show 10K Ohms to the +5 volt rail (through R5) and 12.5K Ohms to ground. ?So there does not appear to be a short holding Tx low. ?Looks like something is pulling Tx low at all times, in both Receive and Transmit modes. ?Hard for me to see how it could be anything other than the microcontroller. ?Has anyone else experienced this with the QDX? ?I installed firmware 1.01a and the EEPROM.QDX and that made no difference.
73, Ben ?K0IKR
