70MHz Power Amplifier GW4RWR

Introduction
This was a MRF1946 driving a 40W device, a 2SC2540. The combination gave over 25W out for about 300mW in.

Implementation
I wanted to avoid the extra bulk, weight and cables of an external power amplifier. PA had to be on the rear panel. The rear panel was drilled and filed out to accommodate the heatsink - which was sawed to reduce its height; it originally had cooling fins on both sides, the inside ones were filed away.

Update: June 2014 - replaced the PA with an RA30H0608m Mitsubishi block. I was having erratic instability issues with my homebrew PA. This block, by comparison, was plug and play. 30mW in for >40W out! I've padded the input to prevent the output from reaching 30W. Halleluja! This felt rather felt like admitting defeat, but I'd wasted soooo much time tweaking/boxing up/reopening.