Review and teardown of Tektronix TCA-1MEG high-impedance Buffer Amplifier System for 7000/70000 series scopes

While ago we got TCA-1MEG dongle for Tektronix oscilloscope to allow high-impedance probing with 7K/70K series.

Features & Benefits

  • Bandwidth – DC to ≥500 MHz
  • Input Impedance – 1 MΩ / 10 pF
  • Bandwidth Limiting – Full/100 MHz/20 MHz
  • Input Coupling – DC/AC/GND
  • Includes P6139A, 500 MHz, 10x Passive Probe
  • TekConnect Interface Delivers Superior Signal Fidelity, Unparalleled Versatility, and Ease-of-use


  • Verification, Characterization, and Debug of Sophisticated Designs in Communications, Computer, and Semiconductor Electronic Environments
  • Jitter and Timing Analysis (Computer Systems)
  • Disk Drive Analysis
  • Investigation of Transient Phenomena
  • Spectral Analysis
  • Power Supplies/Inverters (Switching and Linear)
  • Semiconductor Devices (SCRs, IGBTs, FETs, CMOS)
  • Electronic Ballasts
  • Industrial/Consumer Electronics
  • Mobile Communications (Phone, Satellite, Relay Stations)
  • Motor Drives
  • Transportation Systems (Electronic Vehicles, Electric Trains, Locomotives, Avionics)

It’s useful to take a look inside of unit, without going too deep, as device fully functional and currently in use.
Case holds everything in place with help of four bolts. After removing them, outer cover slide out freely:

Everything holds in place with help of three PCBs and ribbon cables:

Main PCB is using ceramic or alumina-kind substrate to aid frequency response and reduce parasitic effects.

Auxilary signals are routed by ribbon cable and additional FR4 PCB with just breakout connectors and passives:

On BNC input side there is additional PCB to provide coupling with I2C and power for active probes:

Input port support construction:

Here’s TCA1-MEG attached to ours Tektronix CSA7404 and active probe and available options on scope vertical setting menu:

Comparison to passive TCA-BNC adapter, which provides only 50 ohm path for TekConnect interface:

Author: Ilya Tsemenko
Created: July 4, 2015, 7:09 p.m.
Modified: Feb. 11, 2016, 12:06 p.m.