Stan or Patricia Griffiths <w7ni@...>
I have a real problem with the way Bill's and my forum works with my
computer. It takes forever to load and I just don't have the time to wait.
Bill says he can fix it as soon as he gets time to do it. In the mean time,
I have some info for you regarding your 454 nuvistors. See below:
Hello All,This is correct. 154-0461-00's are also known as 8393's.
and I haveYes. The 157-0107-00 is an aged and checked 154-0461-00 (8393). It has been
aged for 100 hours, checked for microphonics and grid current.
CanI don't think the transconductance of the nuvistor is very critical in this
application. I notice 8393's are not checked for transconductance when they
are selected to become 157-0107-00's. I believe the randomly varying
transconductance you see is related to the drift you see. I think the aging
process causes the nuvistors to eventually stabilize.
I notice that Tek uses two part numbers for thePaul, I would just use some plain 8393's in the input circuit of the 454 and
check them for microphonics by jarring the instrument slightly and watching
the trace for noise. I think the cal procedure calls out a test for grid
current. Grid current shows up as a vertical trace shift while grounding and
ungrounding the vertical input at the most sensitive position of the vertical
Hope this helps.