Re: 6DJ8 substitute idea - reverse engineering


Michael W. Lynch
 

It needs to be remembered that TEKTRONIX built their equipment to operate within specifications while using various tubes and transistors which fell into a relatively broad envelope of performance. It is absolutely not necessary to use tubes or transistors on the very bleeding edge of their performance specifications. One needs components that are in spec, but certainly NOT (in most cases) perfection. This is the insanity of those who scavenge tubes from old scopes, these tubes are very likely NOT going to pass ALL of the various and rigorous inspections that "audiophooles" seem to require. Sorting through 50-70 year old USED tubes and hoping to find perfection is one definition of insanity. It would be something akin to sorting through each and every transistor in a circuit, then attempting to get every one of the same type to be matched in every respect; simply impossible. TEK knew that these scopes would run for many thousands of hours and that if any semblance of reasonable accuracy was to be maintained, there have to be considerable latitude in the performance requirements of the individual components. Otherwise the instruments would require calibration before every use as these components will change ever so slightly during each use.

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Michael Lynch
Dardanelle, AR

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