SG505

The Tektronix SG505 is a ultra-low distortion oscillator plug-in for the TM500 system.

Tektronix SG505
ultra-low distortion oscillator Tektronix SG505 Produced from 1980 to 1993 Manuals Tektronix SG 505 Manual (PDF) Tektronix SG 505 Engineering Instrument Specification (PDF) (All manuals in PDF format unless noted otherwise)

Manuals – Specifications – Links – Pictures

Option 01 adds an intermodulation test signal function.
Option 02 adds a fully balanced output to +28 dBm and selectable source impedance with corresponding changes to the front panel connections. It also includes Option 01.

Key Specifications

Frequency range	10 Hz to 100 kHz nom. (typ. 9 Hz to 110 kHz) in four overlapping ranges
Frequency accuracy	3% of dial reading
Output level	+10 dB_m to −60 dB_m into 600 Ω in eight 10 dB steps, plus variable control +2.2 dB to −10 dB from calibrated position
Output impedance	600 Ω
Distortion	< 0.0008% (−102 dB) from 20 Hz to 20 kHz
Sync output	200 mV_RMS sine to 20 kHz, at least 120 mV @ 100 kHz; 1 kΩ source impedance

Internals

The SG505 uses a state-variable oscillator topology employing NE5534 opamps and an N-FET (151-1021-00) based AGC. Range switches change capacitors and AGC time constants, the main dial changes the integrator resistor.

It's internally an surprisingly unremarkable device, no special tricks or selected parts (except for the AGC FET, which is probably some COTS FET selected for threshold voltage and distortion), just an ordinary SVO, some NE553x, standard attenuator and that's it.

Pictures

Front Panel
PCB Right Side
PCB Left Side
PCB Left Side Detail
Front Panel
Option 2 3/4 View
Option 2 Front Panel
Option 2 Left Internal
Option 2 Right Internal