300 Watt MOSFET Broadband Amplifier Using MRF141G

The following segment will provide the enhanced Motorola schematic for any typical application for the MRF141G (which includes parasitic stabilization features), a broadband power RF MOSFET which will place out a conservatively-rated 300 watts across the FM broadcast band. The flange about the MRF141G ought to be mounted to a heat spreader, a copper plate 5/16" thick and 6" x 8", which is then mounted to the heatsink with 6-32 machine screws, if your heatsink is drilled and tapped.

I recommend getting the two transformer assemblies, instead of trying to create them, due to the fact 15-ohm hardline is not straightforward to come across. I've had great results ordering them from:

RF power techniques
17827 North 26th St.
Phoenix, AZ 85032


The component numbers are TUI-9F and TUO-9F along with the price is about $20 each and every.

This amplifier has the notable attribute of variable acquire manage via the bias adjustment trim pot. It may possibly be used in conjunction with an SWR bridge circuit to limit energy output inside the event of large SWR triggered by harm towards the antenna in the course of a storm, or a person inadvertently disconnecting the coax transmission line. For those who wish to apply a failsafe shutdown system that is triggered by reduction of PLL lock, I nevertheless suggest a power provide cutoff relay for total basic safety having said that.

CAUTION: This amplifier operates at very high power ranges. You are able to obtain severe RF uses up if coming in contact with open coax feeder from this amp. Moreover, if your broadcast antenna is roof-mounted, and it need to blow down inside a windstorm although fed at full power from this amp, it may possibly commence a fire in certain sorts of roofing insulation! Be extremely cautious with all the utilization, set up and operation in the unit.

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