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Simple question for RM HLA 300 plus
- Thread starter jimmy870
- Start date
Yes. with an antenna that has 2:1 swr it doesn't accept even 5 watts without shutting down.
Hmm. Fixing an antenna problem by blowing up the amplifier?
Would not be my first recommendation.
Sounds more to me as if your SWR meter is reading lower than the true antenna mismatch. Pretty sure the SWR sensor in the amplifier is set for three to one.
Using the manual found here: https://www.rmitaly.com/wp-content/...ale_tecnico_HLA_300V_plus_rel_2.01_MS1051.pdf
It really looks like TR11 is the shutdown transistor. Pretty sure D16 is the reflected-power side feeding zener diode DZ1 and then into the gate of SCR1. When the reflected-side reading is high enough to turn on DZ1, SCR1 activates and shuts down TR11. No trimpot is evident anywhere in this circuit. The turn-on voltage of DZ1 determines the threshold where protection kicks in.
73
Would not be my first recommendation.
Sounds more to me as if your SWR meter is reading lower than the true antenna mismatch. Pretty sure the SWR sensor in the amplifier is set for three to one.
Using the manual found here: https://www.rmitaly.com/wp-content/...ale_tecnico_HLA_300V_plus_rel_2.01_MS1051.pdf
It really looks like TR11 is the shutdown transistor. Pretty sure D16 is the reflected-power side feeding zener diode DZ1 and then into the gate of SCR1. When the reflected-side reading is high enough to turn on DZ1, SCR1 activates and shuts down TR11. No trimpot is evident anywhere in this circuit. The turn-on voltage of DZ1 determines the threshold where protection kicks in.
73
