Hi to all the group members
Happy to see that the group is still alive.
I have in my workbench a friend's QRP++ with S/N 15XX which needs attention. Las weekend I switched it on and had the S/N on the screen followed by an odd frequency reading. Trying to switch bands through the MEM button did not work properly. My best guess is the the battery is exhausted but I do not know if perhaps the EPROM is corrupted as well.
Although there is audio, no reception in any band with the rig connected to an antenna. I checked it on TX and unfortunatelly just a few mW read on my WM-2 wattmeter. I checked as well the iddle current of the IRF510 and with the power pot set to the minimum PWR the current was 980mA.
As far as the Index-1 mixer is used bidirectionaly I wonder if it is out of order. I remember that the rig was quite sensitive to static. I have still to perform some measurements in order to know what is wrong. Regarding a possible replacement for the Index-1 mixer I think that the Minicircuits SBL-1-MH+ would be suitable and 100% pin compatible. If anyone else has experience with it or any other alternative with +13dBm LO signal, please advice.
I would appreciate any directions/suggestions regarding the repair. I would start checking the LO signal level, then inject a 50microV signal and track it in the RX path. If the mixer is deffective then I would replace it and check again the rig on RX and after on TX to see if the IRF510 is also "ill" or if there is PWR out. Replacing the IRF510 would not be an issue unless having to disassemble the whole rig to access to it. Then set the bias according to the known insructions.
Many thanks in advance for any feedback helping to repair the rig.
72/73 de Vicen?, EA3ADV
Vicenc Llario, EA3ADV