Hi Rich,
The "part 2" of the QST article on the WA2EBY amp notes that you can set a resistor pad up for 5 W input to the original 1 W input that WA2EBY's amp is designed for, but you waste 4 W in that pad so the amp is still driven with 1 W and you still get the designed ~20 W out using 13.8 V DC. ?Are you making a more extensive modification to get more power out?
(Of course, you can get more out of the amp with 28 V drive, up to 70 W with appropriate heat sinking - see Figure 7 of the Part 2 article available at ).
It seems also important to note that the amp is designed for CW/SSB operation only and not digital, because you just can't sink away the heat and not destroy the finals. ?In the thermal calculation section, he writes:
"These [thermal] calculations make it clear that the amplifier should not be used for AM, FM or any other continuous-carrier operation. The amplifier should be used only for CW and SSB operation where the duty cycle is significantly reduced."
73
Phil W1PJE
