190
The Tektronix Type 190A and Type 190B Constant-Amplitude Signal Generators are sine wave sources that use feedback to provide a signal with an amplitude independent of frequency or load impedance, within stated limits.
The 190 was designed by Rodgers Jenkins.
The frequency range is 350 kHz to 50 MHz. The amplitude measurement is made using a peak-to-peak (envelope) detector in an external attenuator head that is connected to the main unit by a special cable. The 190A uses a 6110 double diode tube for the detector. The 190B uses two 1N87A germanium diodes for the detector.
The 190 is useful for measuring the frequency response of a device whose input impedance varies with frequency. If a standard 50 Ω signal generator is used for this purpose, the frequency-domain variations of the input impedance of the device under test will result in frequency-domain variations in the actual signal voltage that is applied to the input. This interaction between input impedance and gain measurements is often undesirable. Having a constant-amplitude source simplifies the measurement.
Key Specifications
- please add
Links
- Tektronix 190 restoration and modification by sv3ora
- Ceramic coils used in the 190 @ vintagetek.org
Prices
| Year | Catalog price | In 2026 dollars |
|---|---|---|
| 1959 | $300 | ~$3,400 |
Internals
The oscillation frequency of the 190B is controlled by a rotary variable capacitor in conjunction with a switchable set of ceramic coils. The variable capacitor rotates together with a drum that serves as the frequency readout dial. The drum is made of cream colored plastic and has a diameter of 5" (12.5 cm) and a height of 4" (10 cm). The frequency knob on the front panel of the 190B turns a rubber wheel which, by friction, turns the drum. The relatively large diameter of the drum provides for precise frequency control, long effective length of the readout dial, and ensures that the friction coupling between the frequency knob and the drum provides sufficient torque to turn the drum and rotary capacitor without any slippage.
The 067-0041-00 modification kit extends the low-frequency range of the 190A.
Pictures
-
190B
-
190B
-
190B
-
190B
-
190B
-
190B Rubber wheel rotating frequency drum
-
190B attenuator
-
190B attenuator
-
190B Attenuator connector
-
190B
-
190B
-
190A Attenuator Internal View
-
190A Attenuator front view
-
Attenuator connector
