[sdiy] A simple 12AX7 vacuum tube tester schematic..

[Matti Kari]

Hi,

> The problem with this tester is that
> for the 12AX7 the manual says:
> GOOD if it reads 22 or more on
> a 120 scale!! Most tested 12AX7's go
> from 15--23..! Not quite acurate.

What comes to my mind is that since your tube tester is quite old, the 
internal components may have aged and that is causing poor test results. 
It may require rebuild.

Btw., I really don't know much about 'modern' electronics, i.e. anything 
that works with transistors ;) But I've been playing around with tubes 
and especially Hammond organs for several years so I think I may know a 
bit about that. Components (especially wax capacitors, carbon 
resistors...) drifting is very common in Hammonds.

-- 
Matti Kari   ||   Vesalantie 38a, FI-00940 Helsinki
maza at maza.fi || http://maza.fi/ || +358 40 838 6607
hammondleslierhodestubeanalogsynthlinuxinternetetc.