Farnell 352C 1GHz Spectrum analyser

[Wanderingfree]

Thank you Jeffrey. A long time since I looked at that formula (back in the 70's I think) I have an AVO 8 Mk 6 so I will use that. Interestingly the previous owner did the resistor mod. It's difficult to imagine that it would have been released with the tube behaving like that unless it's down to the age of the tube but I will as you say leave it as it works.