Can't get a consensus what a cutof reading on a B&K 465 means

[Chris K]

I have 2 10BP4 CRTs, On a Sencore Super Mack on the cutoff setting, one of them has no needle deflection, the other has deflection about 1/3 up the scale. According to the instructions, the higher needle deflecting CRT has better contrast resulting in a better picture.

I tested the same CRTs on a B&K 465. The instructions for measuring cutoff are below:



The cutoff voltage range for the 10BP4 G1 bias should be between 18 and 53 volts.

The low or no cutoff tube on the SuperMack gives a reading of 18V on the 465




The good cutoff tube on the Sencore gives a reading of 40V on the 465 according to the instructions




However, the instructions for the 465 say the LOWER the G1 voltage is needed to move the needle to the cutoff position is a better thing for indicating better tube cutoff.

I am confused. Why does my bad tube on the Sencore have a low cutoff G1 bias cutoff on the 465 indicating, by the instructions, better cutoff?

Dazed and bewhildered. Is this a typo?

[old_tv_nut]

What is the procedure on the Sencore?
I'm looking at a Super Mack manual and don't see a cutoff setting, just four fixed grid bias settings.
http://nestreble.ca/Sencore/CR31%20Manual.pdf