7104: Difference between revisions

The high horizontal speed necessitated using [[distributed deflection plates]] also for the horizontal deflection system, which reaches a  

bandwidth of 350 MHz.  Option 2 adds a horizontal delay line to make the high horizontal bandwidth available for X-Y mode  

at a phase shift of <2&deg; up to 50 MHz, nullable at any frequency up to 250 MHz.

The Micro Channel Plate's amplification degrades irreversibly with operation, in proportion to the log of total charge passed per display area.  For this reason, continued operation with a steady trace and especially at large beam currents must be avoided.  The 7104 contains a "limited viewing time" circuit to assist with observing this restriction.  At beam currents above 0.2 μA, a yellow indicator illuminates, and the beam will be shut down after 20 minutes.  The limit time drops to two minutes at an average beam current of 2 μA, and also limits the average current to that value.  Single-shot display current is not affected.  Despite this limiter, older instruments often exhibit darkening of the screen around the horizontal center line to some degree (see [[Media:Tek7104-200ps-singleshot-sin1-1g.jpg|screen shot]]).

Module A23 (schematic page <14>) contains the mains rectifier,

base drive circuitry, and power transistors of the inverter (aka, switcher).

These transistors produce a 25 kHz waveform that is fed to the primary of T1310 ([[120-1183-00]]),

whose secondaries provide the power for the rest of the scope.

Module A24 (also on schematic page <14>) contains the inverter control circuit

and rectifiers for the secondaries of T1310.

There are independently regulated and current-limited sections

for the −50 V, −15 V, +5 V, +15 V and +50 V rails.

To avoid a dependency cycle, the power supplies for the opamps are separate

low-current, low-efficiency zener clamps that in no way depend on the −50 V, −15 V, +5 V, +15 V or +50 V regulators.

The power supplies for the opamps produce −22 V, −5.6 V, +5.6 V, and +22 V.

To avoid exceeding the opamps' limit of 30 V total rail voltage, each opamp either gets

−22 V and +5.6 V, or −5.6 V and +22 V, depending on whether it needs more output swing

in the positive or negative direction.

The +50 V section produces the reference voltage ("50VS") for the other sections.

It uses a 9 V zener diode, VR1412, as a reference.