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Re-purposing UMTS (2100-2200 MHz) power amplifier for QO-100 use (2400 MHz)
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README.md

README.md

UMTS PA from Fojutowo Microwave Meetup

The amplifier board comes from a commercial 2100-band cell amplifier. I'm planning to retune it to 2400 MHz for QO-100 DATV operation.

Board layout

Amplifier PCB

  1. Signal input
  2. MW6S004NT1
  • RF N-MOSFET
  • wideband matching (datasheet says "up to 2000 MHz" - lol)
  • 18 dB gain, P1dB >+37dBm (nice), 28V
  1. IL05AL(R)2140AAE
  • 2.14G isolator "2G14 P4N"
  • 0.6dB loss between 2110-2170 MHz
  • 10W FWD max
  • 2.4 GHz attenuation? I guess not more than 3dB & poor isolation
  1. X3C21P1-05S
  • 5dB splitter for 2000-2300 MHz
  • maybe wideband just enough - DS ends on 2300 MHz
  • ideal replacement: X3C25P1-05S (2300-2700 MHz) - 4€ @ Mouser
  • why 5 dB? need to figure out the layout (Doherty amplifier..?)
  1. AT2S15N / AFT20S015N
  • 1800-2700 MHz, N-MOSFET
  • ~17 dB gain @ 2100 MHz, P1dB 16W, 28V
  1. AFT21S240-12S
  • N-LDMOS
  • internal matching 2110-2170 MHz
  • ~20dB gain, P1dB 230W, 28V
  • datasheet page 7, 2400 MHz: >20dB gain, -10dB IRL
  1. [SKYFR-000819]
  • 0.5 kW 2110-2170 MHz isolator
  • to be replaced with a piece of semirigid coax?

Steps

  • remove one of the small silver filters and measure its frequency response
  • supply bias voltage to the respective stages, possibly by reusing the AMC7812 chip instead of homebrewing own bias solution
  • read AMC7812 datasheet, check if it has some kind of internal memory
  • identify left-hand-side connectors (where's the main VCC? top left?)
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