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Re: 7844

 

I went back and tested it again revealing some problems which were not
apparent before. The 7CT1N was definitely not designed to operate
this way.

It works well enough in alternate mode but that has some
disadvantages. It should work in chop mode but the logic built around
Q204 and Q208 disables the collector supply between chops (why?) and
the chopping rate is so high that the collector supply amplifier and
probably later stages cannot keep up. Removing Q212 should fix this
and it does allow it to work in a horizontal slot but in a vertical
slot it still has problems with vertical smearing.

So without modifying the 7CT1N, it would appear that using a 7844 is
the way to go.

My 7CT1N is a little weird and is probably not operating quite as well
as it should so it may be that the vertical chopping artifacts are
peculiar to it.

On Thu, 24 Mar 2016 22:18:58 -0700, you wrote:

Hi David,
I never tried this experiment in a regular 4 slot MF. My conclusion was that
I needed the dual independent beams but I don't remember the reason. There
may be a way to do it provided you don't try to make it too complicated and
if I had the ALT and CHOP settings correct. But there would be a lot of beam
switching going on and I don't know how that would affect the curves on the
screen. They may get chopped up pretty badly

The 7844 didn't care whether the 7CT1N was in the Horizontal or the vertical
slot. No beam switching was necessary so each set of curves was perfect. I
did repeat the test on the 7844 with both 7CT1Ns in the vertical slots and
then with both in the horizontal slots and finally with one 7CT1N in one
horizontal slot and the other 7CT1N in one vertical slot. So maybe what I
was trying to prove was the incredible versatility of the 7844. It is
definitely an amazing scope!

Dennis Tillman W7PF
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