some people think the old scopes are slowly.
They use plugins, it`s the old laboratory class.
The most sensitive Inputs are 1A7A differential input plugins, they provide 10µV/cm with a fine s/n.
The fastest warm inputs are Inputs Type "N", sampling more then 1GHz
The fastest spectrum analyzer plugins are 1L40, the provide at maximum 40GHz on 500 Series tube scopes
The 1L5 spextrum analyzer plugin provides full audio analysis from 50Hz up
The 1S2 Plugin works as UHF TDR
Tek549 accept all of them and provide storage by the CRT.
But something can be wrong.... so a triple nickel will accept this high tech plugins also, that works. But this scope is so much hot inside that the temperatur sensitive germanium transistors in the extremly fast plugins can be grilled by the scope, so we will not plug in them in a 555. Other scopes like the 556, all 53x and 54x will do that perfect.
Another thing is the sweep voltage, the oldies have mostly 150V, but some of them only 100V. So spectrum analyzer plugins have a switch at backside to selet the sweep voltage. Also, in the 547, 549 and 556 the sawtooth is connected in the slot and plugins can read it from there, all older scopes must feed the sawtooth by external wire in the front of the plugin to use it.
In the 56x scopes, they use smaller plugins , "3-" series, is the complete vertical amplifier a part of the plugin. This means, you calibrate this plugin personally to its scope ! In another scope plugged the calibration will be lost.
The larger 1- Series plugins have no problem to be swapped bec. the input sensitivity of the slot will be calibrated. Only the verticaL POS in Dual Beam Scopes maybe the plugin must be corrected by screw driver from the front when you swap an upper beam with a lower beam slot.
greetings
Martin