tek 7xx4 series brightness dimming after power on


Alberto, IZ2EWV
 

Tnx Jean-Paul!

Your bench seems to be well equipped, too! I love these plug-in
oscilloscopes, which I dreamt to play with when I was attending
high-school! Having space enough, nowadays they are a must in our benches
and... they have nothing to compare with the present instruments (not to
take anything away from my R&S HMO 3034...).

I cannot tell you about brightness stability of my 7104, because I got it
recently (it has been laying abandoned for at least 10 years in the lab
room of my ham radio club, and finally I decided to make an offer and give
it one chance again!). It was tested there, but for short time and I'm
pretty sure (for the adage: good things come in threes) that when I will
keep it powered on for some minutes - respectfully for the microchannel CRT
- that the filtered AC socket or the RC snubber or something similar in the
switching PSU will give news of them!

73 de Alberto, IZ2EWV

Il giorno martedì 7 gennaio 2020, Jean-Paul <jonpaul@...> ha
scritto:

Hello Alberto: Wonderful to have these vintage scopes, in perfect
operation and on the bench!

Just checked, my 7904 (NOT A) has no variation in intensity after turn on,
and the 7104 microchannel intensifier has a ferocious beam intensity
timeout/limiter, I believe the 7104 time out is inversely proportioned to
beam current. The more modern 2467/B also have the timeout but in a more
advanced implimentation.

Chuck and Dennis, any comments?

Jon



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