On Wed, Mar 26, 2025 at 08:12 PM, Steve N2IC wrote:
With all the BS170's removed, the Diagnostics screen shows the transmitter voltage at 10.9 volts. Ludwig says it should be close to 0 volts, but maybe that is with good BS170's.
Hello Steve,
Diagnostics should show PA voltage near 0 when in RX mode or PTT ON only (no key pressed or key "P" pressed). The PA voltage should be high in TX mode (key "T" pressed). It's clear for good BS170 installed and the driver signals to the BS170 are ok.
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It should be the same when no BS170 is installed. A totaly open Drain of Q507 may go to a different value like Stan wrote. But the Drain is connected via R508 and R509 to GND and via R525 and R526 to GND. The situation should be close to good BS170 are installed and not switched on for transmitting.
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If you see 10.9 V in RX mode something is wrong, Q507 is broken or the voltage to the gate of Q507 is wrong or there is a solder accident around Q507. Please leave Terminal - Diagnostics. This will turn on PA voltage (for some reason) or try to turn it on. Check voltage at S, G and D of Q507. If all values are nearly the same, differences are only a fraction of a volt you have a high probability of a broken Q507.
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73 Ludwig
