MRFE6VP6300H

I have the MRFE6VP6300H in the AR305 circuit now.
I have had to change the input transformer from a 9:1
to a 4:1 and add some inductance to both the input and
output.

The amplifier oscillates at about 230 MHz and the only
way I can stop the oscillation is by placing a capacitor
across the output of the dual FET. This is not optimum.

So far I am getting about 150 watts out with around 27db

of gain at 70 MHz with a power supply of 48 volts and
drawing 6 amps, the device is biased on at 2 amps.

The input match appears quite good but the output match
is lousy. I would probably have been better off starting
with a fresh design and doing away with the ferrite loaded
output transformer which gets very hot (yes I managed to
burn my finger on it by accident). Still these Freescale
devices look to be the bees knees for modern amplifiers
up to 600 MHz.

Innovantennas 6 el 4M LFA-ZTR

For those of you that are interested in antennas here is a picture of my
new 6 element beam for 70 MHz. There is just about enough clearance
to fit it on my mast.

I am currently looking at a Freescale MRFE6VP6300H 300 watt LDMOS
device as a replacement for the venerable MRF151G in one of my amplifiers.
The device is in the same package, runs off the same voltage, and the Freescale
Appnote uses a very similar matching circuit to the AR305 based circuit I
currently have. It will be interesting to see how well it works. The Freescale
device has a much higher gain and it considerably more rugged than the
MRF151G also Digikey sell them for less than the 151 can be bought on eBay.