Hello,
I am hoping someone here may have some experience with RF amplifier operation.
I am using an amplifier operating at ~20-40 kHz (50 ohm), with ~10 ohm transducers. To match the impedance between the two I am using a step up transformer(SUT).
My tests were going well, I was able to run my transducer at ~20 kHz 100 W and monitor the temperature of the output stage transistors. The maximum temperature was ~44C.
However, something has now changed. When I try to repeat the experiment the temperature of my output stage transistors rapidly increases to beyond 60C, even at only 30 W power.
If I remove the step up transformer(SUT), and just have the amplifier running straight to the transducer, the matching is poor, but the increase in temperature does not happen. So the heating is not caused by mismatch of the amplifier and transducers.
We have looked at the SUT and it seems to be ok. We have looked at the amplifier and it seems to be ok. But when the amplifier and the SUT are used together there is a rapid increase in transistor temperature of the amplifier. So we can't use the amplifier for powers greater than 30 W because we don't want to overheat the unit.
We have no idea what is causing this problem. If anyone here has any suggestions it would really be appreciated.
Thank you for your time.
I am hoping someone here may have some experience with RF amplifier operation.
I am using an amplifier operating at ~20-40 kHz (50 ohm), with ~10 ohm transducers. To match the impedance between the two I am using a step up transformer(SUT).
My tests were going well, I was able to run my transducer at ~20 kHz 100 W and monitor the temperature of the output stage transistors. The maximum temperature was ~44C.
However, something has now changed. When I try to repeat the experiment the temperature of my output stage transistors rapidly increases to beyond 60C, even at only 30 W power.
If I remove the step up transformer(SUT), and just have the amplifier running straight to the transducer, the matching is poor, but the increase in temperature does not happen. So the heating is not caused by mismatch of the amplifier and transducers.
We have looked at the SUT and it seems to be ok. We have looked at the amplifier and it seems to be ok. But when the amplifier and the SUT are used together there is a rapid increase in transistor temperature of the amplifier. So we can't use the amplifier for powers greater than 30 W because we don't want to overheat the unit.
We have no idea what is causing this problem. If anyone here has any suggestions it would really be appreciated.
Thank you for your time.