tek 453 scope mod

[m3vuv]

hi all ive a tk 453 scope ive repaired,just out of interest it has  a nuvistor front end,just wondered if anyone here has converted one to a fet front end ,dont need to but may be an option if a nuvistor dies,cheers m3vuv.

[JohnPen]

I haven't converted the Y amp front end nuvistors but have replaced the A timebase nuvistor with the FET equivalent as per 453A.  This came about when the A TB nuvistor failed, proved by nuvistor swapping, plus an associated tunnel diode failure.  I did look at replacing the B timebase nuvistor but as that one was OK I left it alone.  I did investigate whether to update the front end circuitry to FETs but decided to leave well alone.  To modify the existing Y board would be quite complex whereas the TB changes were easily modified on the existing TB board.  Probably one should create a small PCB with the 453A FET circuitry on it and then replace the nuvistor related components.  Maybe someday but I hardly use the 453 these days as it is very much a backup scope in case my regular scope has a problem.

John

[m3vuv]

yup i think i will leave well alone for now,im like you i have an hitachi scope i normaly use,so im using the principal if it aint broke dont fix it.73 m3vuv.

[Cyberdragon]

Nuvistors apparently have a 50,000 hour life, don't mess with them.