Re: 7A21N question


Craig Sawyers <c.sawyers@...>
 

Hi Miroslav

That unattached board is to replace vertical amplifier in your scope and
it's output attaches directly to deflection plates. The 7A21N is just a
carrier for board, as well as for small ceramic based hybrid (located on
main board, towards front panel). That hybrid replaces CRT termination and
facilitates trace position. The connection for trace position goes through
that 4 pin connector on top rear of plug-in, almost never used by other
plugs. One of things in the baggy is a cable that goes from that 4 pin
connector to the hybrid. Note plastic clamp, screw and nut in the
baggy, to
route the two wire cable.
That is all extremely helpful - thanks! I pulled the side off my 7834 and I
see exactly what you mean - a subset of the holes on the 7A21N board fit the
y amp hole pattern, and it is clear where the various cables fit. I guess
that the pattern of fixing pillars in the 7A21N fit the y-amp board that is
removed from the scope for storage.

However I bought this unit for my 7912HB, which is stated to work to 1GHz
with the 7A21N. However, the y amp board in the 7912HB is a very different
beast to the unit in the 7834 and 7904, and there is no way that the 7A21N
susbtitution board will fit. So I guess I really do need a manual for the
plug in to work out how it all fits for the 7912. I suspect that the 7A21N
works with the 7912 *without* swapping out the y amp board (it has more than
750MHz B/W with a 7A29, so the y deflection amp must have a >1GHz bandwidth
itself).

As for single ended input, that is effected dynamically (in real time), by
inserting terminator to inverting input and using remaining one for input
signal.
Sounds good

Cheers

Craig

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