Re: 7904A readout bounce

Roger Evans
 

I have just had a look to see what my 7934 (same Y amplifier and channel switch) does at slow sweep speeds. If I put one of the Y traces near the top of the screen and one at the bottom and set the sweep speed to 100msec/div then I see a small shift of the top and bottom readout positions as the beam alternates between the two traces. The movement is at most 0.05 of a major division, quarter of a minor division When the upper beam is displayed both readouts move slightly downwards, when the lower beam is displayed the readouts move up slightly. If I put the two traces near each other, anywhere on the screen, the readout does not move. At 10msec/div the movement is about the same but more objectionable, at anything faster than 1msec/div the readouts are steady. This seems consistent with thermal effects and David explained it very clearly.

IWhat sweep speeds are you using and how much movement of the readout do you see?

Roger

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