211: Difference between revisions

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{{BeginSpecs}}

{{Spec | Input Impedance | 1 MΩ // 130 pF }}

{{Spec | Sweep Range | 200 ms to 5 μs  per division }}

{{Spec | CRT | [[154-0642-00]] (<B080000) or [[154-0699-00]], 6(V) × 10(H) }}

{{Spec | Dimensions  | (H/W/D) 3" × 5.2" × 8.9" (7.6 cm x 13.2 cm x 22.6 cm)  }}

{{EndSpecs}}

==Internals==

Triggering is done using  U65 [[155-0048-01]], which contains a horizontal amplifier (for external), trigger, and sweep generator.

The output of U65 drives the second section of dual output amplifier IC  U25 [[155-0057-00]] whose output is fed to the H-plates via output transistors  Q119/Q122.

Instead of the transformer, a capacitive divider is used to step-down down the line voltage. C210 is the capacitor for providing charging voltage and C212 gets parallel to C210 for line operation. The value of these capacitors needs to be adjusted based on operating line frequency and voltage. Manual suggests recommended values of these capacitors for common line frequency and voltages. Input AC must be sinusoidal to offer the correct reactance to step-down the line voltage.

Regarding his experience as a Tektronix manufacturing engineer for the CRTs for the Miniscope

<blockquote>

I was the weld lab manager too.  We designed, tested, selected electrodes, and weld

settings for the elements inside the CRT.  

The CRT division had a great concept where the new engineers work at each station

for a week or two learning all the processes and actually making parts.  The side

advantage is you meet the production people and when you need something you know who

to ask.

using a pilot program where the same assembler worked on all phases of the tube.  

The other CRT's were being built by a person that only did one portion of the

assembly. As an example, the deflection plates were assembled and carefully aligned,

the next operator may not realize that and if accidentally bent, tried to bend them

perform every process, they could see what was important and what could be improved.

The primary goal was to find ways to improve the processes.  By performing all

The cathode for the Miniscope CRT was a critical part of the design.  It took

several tries to get that right.  It was being done in conjunction with our partner,

flat wire.  This reduced the power necessary to heat the cathode to the required

temperature.  This was important for a battery operated device.  The spacing

The cathode was a small disk with the triple carbonate coating blown on to the

surface at a precise thickness.

aimed off the screen during the horizontal retrace.  This was faster and easier to

control with the associated electronics than changing the negative high voltage with

respect to the grid.

Glass rods hold the elements in place inside the CRT.  Having so many elements

embedded in such a small glass rod made them fragile.  The rodding process was

carefully controlled for temperature and time.

The bulb of the CRT was ceramic with an internal gold plating as the anode.  The

graticule.  After the faceplate was bonded to the bulb, the phosphor was allowed to

settle in a liquid onto the faceplate.  The liquid was poured out and then aluminum

resist burning the phosphor and reflected the light from the back to the front for a

brighter sweep.

The electron gun was welded to the stem with the pins.  That was inserted into the

neck, that was previously bonded to the ceramic bulb, and using a lathe with a

flash, the better is absorbed the impurities, but too much flashing could short out

metal parts.

A coil was wound around the CRT to allow for a trace rotation adjustment in the

oscilloscope.  This would correct for any small gun rotational alignment.

==See Also==

* [https://www.youtube.com/watch?v=BJTZIawR1Iw LazyElectrons Video: Tektronix 211 - Internals, battery replacement]

==Pictures==

Tek_211-wHood.jpeg | 211 with Viewing Hood Part [[016-0199-00]]

200 series compared.jpg | Tek [[214]] (top), [[213]] (center) and [[211]] (bottom) stacked

Tek_211-BatLevel.jpeg | 211 Battery charge meter

Tek_211-Internal-Top.jpeg | 211 Internal top

Tek_211-Top-WoAmp.jpeg | 211 Top w/o amplifier board

Tek_211-Internal-Bottom.jpeg | 211 Internal bottom

Tek_211-Int-Side.jpeg | 211 Internal LHS

211 int 05.jpg | Input Board (rear)  

211 int 02.jpg | Amplifier board  

211 int 03.jpg | Amplifier board  

211 int 06.jpg | Amplifier board (trace side)

211 int 04.jpg | Power supply board

211 int 07.jpg | Power supply board (trace side)

Tek_211-OPTransistors.jpeg | Output transistors

Tek 211 battery pack.jpg|Tek 211 internal battery pack

</gallery>

[[Category:200 series scopes]]