Hi Noel,
Okay, I have had the B40D coupled up on the bench - Took me a while to make up all the Mk 4 connectors
Some details of the test equipment used:
Marconi 2022D RF Signal Generator set to 1.07MHz, 5uv carrier, 30% modulation at 1000Hz
Marconi 893 C Output Meter - Set to match 600R Impedance, and running on 3W FSD
With all of these settings applied, the AF gain on the receiver set to maximum, the Bandwidth set to 8KC, and the AGC off, RF gain to maximum.
I measured a peak (distorted) power of 2.95 Watts
At undistorted (to my ears) output, I measured 2.5 Watts
I had to back the AF gain down to clear the distortion.
So, in a nutshell, the amplifier in mine will certainly do 2.5 Watts.
I guess the question now is, why isn't yours doing the same?