BARC-IIFC collaboration meet RF Solid-state Power Amplifiers at 325 MHz RFSS, TPD, BARC

Outline of the presentation Proposed Projects Specifications Scope of work Design Assembly Tested results RFSS/TPD/Physics Group/BARC

Solid-State Amplifiers Development Deliverables under the collaboration 1 kW, 325 MHz SSPA 3 kW, 325 MHz SSPA 7 kW, 325 MHz SSPA RFSS/TPD/Physics Group/BARC

Specifications 1.Center frequency : 325 MHz 2.Bandwidth : 1 kHz 3.Power output (1 dB), CW : 1, 3, and 7 kW 4.Gain (1 dB), minimum : 67 dB 5.Gain Stability : +/-0.5 dB 6.Cooling : Water Cooled 7.Input & Output VSWR : 1: Harmonics & Spurious : <30 dBc 9.Efficiency (Total) : > 60% RFSS/TPD/Physics Group/BARC

Scope of work Modules design & development ( 800 W – 20 nos.) Feed Back circuit design and development Interlock and protection circuit design (internal to RF amplifier) Power combiners & splitters design Directional couplers design Heat sink designs PCBs design & Fabrication Integration of sub-systems RFSS/TPD/Physics Group/BARC

Design Initial design based on FR4 Based on FR4 thermal performance, design changed to PTFE Design based on non-linear model of device Push-pull amplifier Class AB design Matching networks with micro strip- & capacitor Simulated power output Vs freq.Simulated efficiency Vs freq. RFSS/TPD/Physics Group/BARC

Test Set-up of RF power module  One amplifier prototype assembled  Bolted to water cooled heat sink  Test set-up arranged with  SMPS power supply  Power meters along with sensors  VNA & SPA  Signal generator  Drive amplifier  Spectrum Analyzer  Directional couplers  Test Load RFSS/TPD/Physics Group/BARC

Test results 325 MHz Amplifier with FR4 substrate 1.Short time test (1/2 hr) : 1 kW 2.Long term test (8 hrs) : 800 W 3.Power gain (1 dB) : 19.5 dB 4.Efficiency : 68 % 5. Input VSWR : < Harmonics : <-40 dBc 325 MHz, 1 kW board Power splitter / combiner 1:2 Power Combiner / splitter: Two 1 kW boards will be combined with this power combiner. Each 1 kW amplifier will be operated at 800 watt for achieving long term stability RFSS/TPD/Physics Group/BARC

Test Results of 325 MHz RF module Recorded power variation over 8 hours Hours Output Power RFSS/TPD/Physics Group/BARC

Comparison of Specifications Specification Fermi Lab SSPA Developed Remarks Center frequency (MHz)325 Bandwidth (kHz)100>100 Power output (kW)10.81 kW test is under progress Power Gain (dB)67>70Inclusive of drive PA Efficiency (%)6068 Gain Stability (dB)+/-0.5<+/-0.5 Harmonics (dBc)<-30<-40

350 MHz, 1.8 kW SSRFPA An amplifier has been assembled using 8 power modules (each of 250 watt), pre-driver, driver and 8-way power divider / combiner along with a protection circuit. This total RF set-up has been tested up to 1.8 kW. The power gain and efficiency of this amplifier is at 23dB and 43% respectively. RFSS/TPD/Physics Group/BARC

1.Preliminary testing of 325 MHz, 1 kW amplifier has been done 2.This 1 kW RF amplifier will be completed in all respects inclusive all its other sub systems. 3.Based on this basic 1 kW RF amplifier module, next 3 kW and 7 kW RF amplifiers will be developed. Future Work RFSS / TPD / Physics Group / BARC