Re: v4 ubitx stuck in transmit



Check your T/R line from diagram and see if there is voltage on it, then it will TX even with the raduino removed.
I suspect a speck of solder shorting somewhere.

Check K1 relay voltage on pin 8 and 9 - both should be 12V (means OFF) if one pin is 12 and other 0V then you may have
a shorted Q15.

Good luck!

At 27-01-20, you wrote:
Definitely a mystery. I thought I was in final stages of mods - last step was installing a second 45 MHz stage in transmit path. I powered on - found my ubitx stuck in transmit. I removed radiuno - still stuck in transmit. Finally I removed the xtal filter mod that was across R22 (yes I including a block cap and left the 50 ohm resistor) - still stuck in transmit - I do currently have nothing across R22 but that should not matter, I don't think for this circumstance.

Curiously, the bi-color LED is not showing red, but white - meaning I think both T and R might be engaged? Anyway that's my only clue at the moment. I guess next step is to see what is going on at the lower side of the board. None of my mod activity seems to be in vicinity of TR circuitry so I am puzzled.

Okay back to studying schematic to see where I could cause this circumstance, apparently on the main board.

73 Curt

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