11A52: Difference between revisions

* [[Media:070-6114-01.pdf|Tektronix 11A52 User Reference Supplement]]

* [[Media:070-7391-99.pdf|Tektronix 11A52 Extended Service Manual]]

* [[Media:070-6786-00.pdf|Tektronix 11A52 Service Reference]]

<!--* [http://w140.com/tek_11a52_nvram_replacement_addis.pdf 11A52 NVRAM Replacement Guide by John Addis] -->

* [[Media:Tektronix 11k plugin NVRAM replacement.pdf|Tektronix 11k Plug-in NVRAM Replacement]]

{{Spec | Bandwidth | DC to 600 MHz plus 100 MHz and 20 MHz [[Bandwidth Limit Filters]] }}

{{Spec | Deflection | 1 mV to 10 V per division in 1% calibrated steps}}

* High-Resolution Calibrated DC Offset

* Fast Overdrive Recovery

* Input 5V RMS overload protected with manual reset

Each input channel has a separate 50 Ω attenuator containing two ×10 attenuators, a skin effect correction network, an AC coupling capacitor, a signal pickoff for the input protection network and a switch selecting the calibrator or signal input. In normal operation the calibrator signal to the attenuator is instead connected to ground.  

The signal output of each attenuator feeds a hybrid through a (blue) 50 Ω cable.  The hybrid looks like packaged M377s found in other instruments. It contains a 50 Ω termination resistor, a diode bridge that protects the M377 from transients too fast for the input relay to react, and an [[M377]] amplifier IC.  The input signal is connected to the + input of the [[M377]] amplifier.  The cable lengths set a standard delay per plugin.  

The M377's − input is connected to the [[ACVS|ACVS (Analog Control Voltage System)]] output located on a daughter board.  

The 11A52 is very similar to the 11A32.  There are a few differences.  The difference in bandwidth (600 MHz vs 400 MHz) is due almost entirely to the difference in input attenuators.  The 11A52 50 Ω attenuator is passive and contains no amplifier.  Additionally the 11A52's M377 sees a 25 Ω source impedance (a terminated 50 ohm transmission line). The 11A32's M377 is driven by the 50 Ω output impedance of the [[M474]].

The [[11A32]] and [[11A34]] have only one transient response adjustment per channel.  This adjustment affects the high frequency response of all six of the M377's fixed gain settings (1 mV div - 50 mV/ div).  The 11A52 has the added luxury of a high frequency adjustment for each of the M377's six gain settings to optimize the response at each setting.  These settings are manually set under computer control and stored in NVRAM.  They need to be reset when the 11A52's NVRAM is replaced.  The NVRAM's internal battery typically lasts 20 to 30 years.

If you care to write down the 11A52's twelve calibration constants while the NVRAM is still alive, you may simply enter them into the new NVRAM.  If you do not write them down, you may observe the transient response and set the calibration constants also via a personal computer.  Instructions for this are found at [[11A-series plug-in NVRAM replacement]].

An analog switch injects test currents, positive and negative, into the summing junction at the input of each M94. The outputs are checked by the self-check software routine.