[vintage_8bit]

I haven't rechecked my voltages comparisons between the 163 and MkIII yet due to the inconsistencies between my two meters.

I am confident with the EL84 measurements I made with the DC bench supplies though, with the HT at 250V bias at -7.3V results were aI = 53mA, mA/V = 14. This matched the 163 results close enough I thought?, see post 6.

I coudent see any signs of oscillation on the MkIII using an isolated scope. Please see attached, pictures of the grid waveform with and without the link in.

What I have tried since though is isolating the grid circuit to the valve using the thumb wheel switches and applying the 7.3V bias (as per the AVO data book for the EL84) with a DC supply. It was nice to see the anode current now the same as the D.C. bench tests, and the 163 at 55mA. Not sure what's next yet as cal procedure for bias appears to work. Do the waveforms look correct?............. I have just found similar waveforms in Martins "AVO VCMs Circuit Comparisons" literature.