My?Tuna Helper ][+ is experiencing issues with the T/R switching & after mucho troubleshooting my board looks a bit hacked as I touched up quite a few solder joints & changed out Q1, etc. I have the PN2222A pin out so I know it goes backwards to the silkscreen layout, but I changed it anyway since the first time around I installed it the other way automatically (never transmitting until this weekend), even though I read the instructions saying otherwise. Basically I seem to loose signal switching after the intersection of the 1K & 47K resistors. I measured with my RF probe, then removed the 47K part to doublecheck as the 2.2uF cap influences the measurement big-time.
How much transmitter power is needed for the T/R switching to work? I should hear the relay click & return depending on the Fast or Slow jumper settings, but Q1 is not switching at all. I measure 0.8 volts B to E, & 12.45 volts at the collector. I assume 300mw is enough TX power, but that could be an issue also that I did not consider. The PWR/OP SPDT switch works great as that is how I measured TX power originally.
I knew I had an issue as the Mute function on my Tuna Helper seems to mute my Icom comm. receiver all of the time when I plug in the RCA jumper. I could easily reverse the logic on the relay once I get it to switch with real QRPp TX power. But first I need Q1 to switch so that one side of the relay coil goes low to cause it to click over.
I have an older non-+ version of this kit unbuilt, I might build it up as well for comparison. Then take RF probe readings to compare.
Cheers,
Davey --KU9L?
David Knapp