Teardown of a Ericsson Radio Base Station RBS3206 (cell site amplifier)

[madsbarnkob]

All high resolution pictures: http://kaizerpowerelectronics.dk/teardown/ericsson-radio-base-station-rbs3206-teardown/



The RBS 3206 macro is an indoor Radio Base Station with one to four carriers and one to  six sectors at 20/40 Watt RF output power per carrier.

Besides the teardown and circuit analysis, there is also a deeper look into ceramic resonator filters, for some of the other components I have explained about these in earlier videos:
Up/Downconversion explained: https://youtu.be/qO127zY3voE?t=865
SAW filters explained: https://youtu.be/qO127zY3voE?t=963
Doherty amplifiers explained:

[4CX35000]

Doherty is 1930's technology, heavily used by high powered medium wave transmitters running up to 600 KW.

At unmodulated carrier the Class B stage (Carrier) is saturated, whilst the Class C stage (Peaking) is turned off. At Peak Envelope power, both stages should be saturated and therefore giving maximum efficiency. From memory the power efficiency of the amplifier looks like a bathtub curve were maximum efficiency is at 0% modulation or 100% modulation, and least efficient at 50% modulation.

[madsbarnkob]

Doherty is 1930's technology, heavily used by high powered medium wave transmitters running up to 600 KW.

At unmodulated carrier the Class B stage (Carrier) is saturated, whilst the Class C stage (Peaking) is turned off. At Peak Envelope power, both stages should be saturated and therefore giving maximum efficiency. From memory the power efficiency of the amplifier looks like a bathtub curve were maximum efficiency is at 0% modulation or 100% modulation, and least efficient at 50% modulation.

Actually it is most effiecient at 50% and 100%, the "bathtub" you refer to is between 50% and 100%.