The 58x series were the first Tektronix scopes to use distributed deflection plates and the last to use distributed amplifiers for vertical deflection. At 100 MHz (down-rated to 95 MHz in 1962 and 85 MHz for the 581A) with the Type 80 plug-in and up to 85 MHz with the dual-channel Type 82, they were the highest-speed general purpose scopes of Tek's tube scope era (the 1 GHz 519 was specialized with no vertical amplifier).
The vertical signal path of the 581 is the same as that of the 585. It uses the T581 CRT. Type 581 scopes with serial numbers up to 510 use an all-tube trigger circuit. Starting at serial number 511, the 581 uses tunnel diode triggering.
A Type 581A was introduced in 1963, and it is specified to have a bandwidth of 85 MHz instead of 100 MHz. The somewhat relaxed bandwidth specification improved CRT production yield which had been a problem when the scope was specified to 100 MHz.
581 vertical output amp (distributed amplifier) driving CRT