I ran my 49-er at 11.5 volts accidentally and destroyed the original D882. Up until it smoked, I was getting around 5-6 volts out. When I replaced the D882 and adjusted the output of R1, I'm now getting about 3 watts out - which is just fine. I wouldn't advise running the D882 any higher than the 4 volt peak to peak voltage as the manual states. Even at 3 watts out, I'm making lots of contacts with the thing. It's all in the antenna. :-)
I'm not sure it's worth the gain to ramp the voltage above 12V. Running 1.8W versus 3W probably isn't going to make much difference, but I think running at 13.8V runs a real risk of smoking the final. If you do run at higher power, make sure you don't leave the key closed too long.
Right now my 49'er with the DDS-VFO is managing 1.65-1.8 watts out as shown on my LP-100A and going into into a tuned doublet. I don't have a heat sink on the D882 at this time.
My 49'er and DDS-VFO R1 has been set to 4V P-2-P via my Tek 2213A oscilloscope.
I run a Elenco XP-752A Variable power supply. It's set at 12.0V even, and the unit is drawing 0.17a current idling, and a slight tad more on TX.
What I'd like to know is what voltage do most users run their 49'ers with the DDS/VFO at? (Assuming 12V levels)
I've seen that 49'er output wattage varies from 1.5 to at or above 3 watts based on bit's and pieces I've found on the web. I have the ability to go up to 13.5V but would like to hear from others on what you are actually seeing out of the unit and how the higher V affects the output wattage.