life or old scopes and CRTs. Note rom Tektronix.

[Opcom]

The attached note is from Tektronix publication of the 1950's. When a CRT or oscilloscope is idle for a long time, a procedure helps to "reactivate" the cathode.

I do not know what the trouble cause is, but suspect the small precision clearance between the cathode and grid, a common thing in CRTs of most types, and more so in precision CRTs.

The procedure reminds me of the gentlest procedure for CRT rejuvenation. IMHO chemical stuff builds up in the tolerances and this causes problems either shorts or emission blockage.

Keep the old scopes shining!

[WQ9E]

Interesting Patrick and thanks for posting!  I have several older Tektronix scopes dating back to a Type 514AD that belonged to my father.  It along with my dual beam 555 and 556 scopes don't see much use anymore since my main bench scopes are a pair of 7854.  There was a service note from Tektronix in one of my 7904 manuals indicating a resistor change which lowered heater voltage for replacement CRTs and mine had been updated to reflect that change.