开云体育

Got my low band QMX up and running again... Kapton tape to the rescue. Did the 2.5mm power connector, as well as the sides and bottoms of both encoders on the control board.

QMX 80-20
Rev 3
Firmware 1_00_018

Power : 8.00V 0.500A bench supply
QRP Labs 50 ohm dummy load

Firmware install : ok
Power up : ok
LCD working : ok
Terminal emulator : ok

Band config screen looks similar to the manual section 8.5

Hardware test : all ok

Audio filter sweeps : 20,30,80 have straight yellow lines, red line is only about 10-20dB down ?

RF filter sweeps : 30,40,60 & 80 look messy ?

Image sweeps : not sure I understand what I should see here ;-)

SWR sweeps : 20, 30 & 80 look ok, but issues with 40, 60

LPF sweeps : i think 20,30 & 80 look ok ?

Any comments / suggestions appreciated.

ZL2EF

When in doubt, resolder the leads on L401.

I ended up rewinding L401 three times, and resoldering the leads about six times altogether before mine was right.? I still wasn't completely happy with the sweeps, but the radio did great during the CQ WPX contest - I'll take results over diagnostics any day!

I had a look at the schematic and identified the toroids, capacitors, diodes and inductors related to 60/40m. Re-flowed 5he solder on all of those and the swr and lpf sweeps look normal now.

Still have weird audio filter and image sweeps, but will start a new topic on that.

This is what I did, may be of help to others...