Digital MOSFET 15W FM RF amplifier, with SWR meter

This wideband no-tune FM broadcast band amplifier unit was developed to supplement the PCI MAX line of fm transmitters, but will work great with any LPFM (low power fm transmitter) on the market. It takes the signal and amplifies it to the full power of 15W. It can also be used to extend the range of stronger small transmitters, up to about 1W of output power (amplifier's sensitivity can be adjusted with jumpers). No tuning is required as the amplifier is a fully wideband design. It also features a built-in SWR foldback protection with 10-LED bargraph display. Unit works from a stabilised DC mains power supply (12-15V at 3A) or car battery.

The manual for this unit can be found here.

Here and here are two small movies to show how it all works. Its best to save it to hard disk and than play with VLC or Windows media player. Our Cyber Max Micro test unit was used to drive the 15W booster+. A dummy load was attached and Daiwa CN-101L SWR/POWER meter . 15V power supply was used to power the booster.

What's great about this unit
- Power is now adjustable digitally with UP/DOWN keys, adjusted power is shown with 10-LED bargraph display
- SWR meter included, current value is shown with 10-LED bargraph display
- Truly wideband, no tuning necessary
- SWR and TEMP protection circuit
- It CAN be used with PCI MAX cards or other small FM transmitters (up to 1W max.)
- FAN speed is regulated and it spins down when not needed

Technical specifications:
- RF Input Power: 5-1000mW (selectable via 2 jumper)
- RF Output Power: 10-15Wtyp (20W max)
- RF Output Power: Adjustable from 0 to max via up/down keys.
- Output connector: BNC
- Output Impedance: 50 Ohms
- Input connector: F (designed to match easily with the PCI MAX transmitters)
- Input Impedance: 50 Ohms
- Frequency Range: 85-110MHz
- Spurious/Harmonic rejection: Harmonics: > 50dB min.
- Built in SWR fold-back protection (with a 10-LED bargraph display)
- Power Supply Required: 15V/3A
- PCB board: 145x110mm, double-sided professional PCB
- Enclosure: 105mm(W)x115(L)x35(H)mm, black anodized aluminum
- Size matches the cyber max micro enclosure