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  • Manufacturer: Enigma Broadcast

300W FM Broadcast Reference Design using the BLF278

$19.00 USD (excl. VAT)
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Product description

The FM300v2 is a broadband 300W amplifier for the FM broadcast band. We've recently managed to source a quantity of used BLF278 transistors at a great price, so have provided a reference design so that a low-cost, high performance amplifier can be constructed from the plans provided here. 

This design is available as a paid download. Files will be available once a purchase is made. 


  • Broadband 300W FM broadcast amplifier operating from 87.5-108MHz
  • Only 0.5-1W input drive required
  • Microcontroller controlled on-board 2-stage thermal and SWR protection 
  • Fault output to power down exciter during a fault
  • High efficiency - cool running
  • High reliability - designed for years of continuous use at 100% duty 
  • Low harmonic content, suitable for direct connection to an antenna
  • PCB Gerber files and full construction details with parts list provided as a digital download 


  • Power gain 25dB typical
  • Gain flatness +/- 1.3dB
  • Output power 320W typical
  • Efficiency 68-78% (73% typical)
  • Output power 270-345W (320W typical)
  • DC Current consumption (main supply) 48V, 8.5-10.5A (9.5A typical)
  • DC Current consumption (pre-drive) 12-15V, 1A
  • Input power 0.5-1W
  • Harmonic output -74dBc typical 

We sell many of the parts to make this amplifier, and full details are provided on the parts list. 

A limited number of PCBs are available here

A programmed microcontroller for this design is available here



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