Technical Manual

ATLAS 4500 Multimode Station Technical Manual July 2016 A-11
Controller Board Appendix A - 700/800 MHz Circuit Descriptions
A.3.2.5 Power Coupler
The PA feeds an output RF coupler port, providing about 6 dBm at 100 W output.
This is for DPD use, and is fed to the Exciter.
A.3.2.6 Power Detector
Next, the output RF passes a directional coupler. This is used to sense PA forward
and reflected power. The FWD VOLTS goes to CN – 11. REFL VOLTS goes to
CN – 12.
Detector sensitivity gives ~ 3.5 V at 100 W at center of the band.
A.3.2.7 Harmonic Filter
Next follows a 4-stage elliptical low pass filter inside a screened cover. This
provides attenuation of all harmonics.
A.3.2.8 PTT Power Control
The PTT line from CN – 8 controls the Switch TR2. This switches 24 V and allows
PA FET bias to operate. PA bias is nominally set for 4 V at CN2 – 7 and pot-
adjusted for ~3 A.
A.3.2.9 Auxiliary Circuits
The PA contains a 3.3-V regulator IC7 with 5 V in from CN2-14, a temperature
sensor TS1 on CN2 – 13, and a serial flash IC11 using I2C bus on CN2- 9, 10.
A.4 Controller Board
This section contains information on the following Controller Board components:
• PA Interface
• Exciter Interface
NOTE
A harmonic filter network is added to keep response flat.