Hi David,
Here is what the head of Tek's Laboratories (he also designed the vertical
deflection plates in the 7104 CRT) had to say:
"Dennis: I turned on both my 7904 and SC503. In a ten minute span I did
not see any change in the trace brightness. So I don't have any evidence
that there is such a drop -- at least on these two scopes. There was
nothing that we ever recommended from the CRT group that would have led to
such a design feature. Maybe it's caused by a noisy intensity control."
Dennis Tillman W7PF
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-----Original Message-----
From: TekScopes@... [mailto:TekScopes@...]
Sent: Friday, December 19, 2014 9:56 AM
To: TekScopes@...
Subject: RE: [TekScopes] 7904 trace dimming
Hi David,
I have seen that on other 7000 scopes and even on some of the small TM500
scopes (SC501, SC502, SC503, SC504, and MR501). It is subtle. It was the
subject of some comments on the forum many, many years ago.
I will ask a friend of mine who was in the CRT group if he knows what causes
it.
Dennis Tillman W7PF
-----Original Message-----
From: TekScopes@... [mailto:TekScopes@...]
Sent: Friday, December 19, 2014 8:55 AM
To: TekScopes@...
Subject: [TekScopes] 7904 trace dimming
Hello All,
I am noticing that as my 7904 is warming, the trace dims. It does this
about 3-5 mins after power up and does so all at once. In other words, it
is not gradual dimming. I need to increase the intensity by one mark on the
knob scale in order to return the trace to similar intensity as before it
dimmed. It does not dim beyond that throughout the day after this initial
"dimming."
Has anyone else experienced this?
Just tinkering in the lab.............
Cheers,
David
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Posted by: d.garrido@...
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