I picked up a clean HW-8 a while back and finally did a mod I've wanted to try for a while. I designed a super simple amp using a single MRF-454. It uses a 9:1 broadband balun on the input and output in order to sort of match the 'few ohms, mostly resistive' input and output impedance of the device to 50 ohms. The transformers are wound as a 3 to 1 ratio on binocular style cores. I mustered this little perf board amp into the HW-8, placing it electrically after what was the original final amp stage but before the low pass filter section. That took advantage of the existing LPF architecture, and dovetailed perfectly with my inherently lazy way of doing things. I fired up the HW-8 and saw over 10 Watts output on 40 meters when running on 12 V. When I increased the voltage to 14 volts I saw about 17 Watts out. The heat sink is just a piece of metal attached to the MRF. It's reassuring to know I'm using that device way below its rated output just in case I try to load the rig into a case of Budweiser at the next Field Day. Next, just for grins I ran my monster HW-8 10 Watts into my ALS-500M. That gave me about 200 Watts output CW. Yep, we ain't runnin' QRP no more, nope......
