Re: 2465B calibration temp?

Chuck Harris <cfharris@...>

1) there is absolutely no need to cool anything in the
2465B while it is out of the case. Not U800, not anything.

The only caveat to that is don't leave the scope laying on
the bench with the front panel overhanging the bench.

2) calibration can be done over a very wide range of room
temperatures, see the manual.

If yours is outside of the specs published in the manual,
and, it was inside of the specs in the manual when you calibrated
it last, you have a bad part that needs replacing... likely a trimmer
pot... especially likely one of the 10K resistors on the A5 board,
if it is a late serial number 2465B.

Electrolyte from failed SMD electrolytic capacitors etches the
elements of the 10K reference resistors, and if they weren't
replaced, they will drift ever upward in value. Similarly, any
electrolyte left on the A5 board will be hygroscopic, and make
the circuits on the board drift.

-Chuck Harris

Jean-Paul wrote:

Raymond and Victor,

Many thanks! I have done full cals on these but some years ago. Am Aware of cooling of A1 PCB, U800 etc with case open.

I have TEK manuals printed originals, PG506 and TM501, attens, terms etc.

To précise the questions:

IF the scope was already full CALed but the V or H is still off 1-3 % (perhaps bad first attempt at CAL?) can the V/H CAL be done with case closed or it must be open to reach trimmers?

Best Wishes,


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