On Sat, Mar 15, 2025 at 11:20 PM, lars anderson wrote:
i had blown the finals. i replaced them. then i ran diagnostics - normally - i verified that the transmit power (into dummy load) was back where it used to be. thinking it was solved i went back to the rtty contest and during my first transmit - the power supply went into current limit & drew down the voltage to ~6v.
Lars, a broken PA may cause a demage of Q507 the PA voltage regulator. (I saw this some times when other HAM gave me QMX for repair.) In this case the PA voltage is high all the time. In this situation RX may be ok and after replacing the BSS170 TX is working basically. But you don't have envelope shaping. This is dangerous for the PA like others wrote before. Please use Terminal and go to Diagnostics. Without TXing the PA voltage should be 0.x V and not some volt.
For debugging a possible broken Q507 be aware the PA voltage is switched on also in RX mode except you are in Diagnostics mode (or you switched off this feature in a deep configuration menu.)
?
73 Ludwig
