I am working on doing a restoration on a Tektronix 485 for the lab and I have been arguing with it for a little while. I am curious if anyone has run in to a scope that does not like to trigger at low frequencies? I am currently working on the 50 Ohm calibration and it seems that the scope in 50 Ohm mode REALLY does not like to trigger under 1.2Mhz. So it is struggling with 50 Khz cal signals. Vertical amplitude is good trigger is flakey. I have heard that some of these the TD¡¯s go kind of deaf at the high speed side of things but not the low side. Any ideas what might be causing this. I am continuing to investigate further.
Zen
