This stage handles the muting of the RX section when I PTT goes high. After soldering in all the component, the testing went according to plan, until taking resistance readings of the power rail.
The initial current readings were as expected, but when I switched the DMM over to read resistance levels, nothing registered. I was expecting to see around 7 Meg ohms at the 12V test point, 950 Ohms at the 5V test point and 10 K Ohms at the 3.3V test point. Resistance readings of the band pass filter’s secondary windings were fine.
That’s where I left things for the night. My philosophy is to sleep on it when things get tough.
It was at around 4am the next morning that I woke suddenly with the answer as to why the resistance readings for the power rail were non-existent: I was taking the readings with the power to the PCB turned on! So I took readings again, this time with the board dead and all was just as it should be.
Still flushed with success, I decided to push on and continue with the rest of the testing. All readings on my DMM were as they should be, so it was time for the best part, to solder in a temporary antenna, connect up a lead to the input of the computer’s sound card, start up the software (Rocky in my case) and see if the rig could detect a test signal on 7.046 MHz (the centre frequency of the 40m band that the rig is tuned to).
Now came the moment of truth.
Once the rig has been completed and installed into an enclosure I will try to filter out any signal images that mayexist.
This completes the build of the main board. Next is the difficult part: the PA filters.