FG502

The Tektronix FG502 is a function generator plug-in for the TM500 system.

Tektronix FG502
function generator Tektronix FG502 Produced from 1974 to 1993 Manuals Tektronix FG502 Manual (OCR, PDF) (All manuals in PDF format unless noted otherwise)

Manuals – Specifications – Links – Pictures

It generates low distortion sine, square, triangle, positive and negative pulse, and ramp waveforms from 0.1 Hz to 11 MHz.

A squarewave trigger is available at the front panel. Variable DC offset is also provided.

Α voltage-controlled frequency (VCF) input controls the output frequency from an external voltage source. The output frequency can be swept above or below the selected frequency to maximum of 1000:1 depending on the polarity and amplitude of the VCF input and the selected output frequency.

An external gate input allows the generator to operate for the duration of an externally applied gating signal. This mode provides either a single cycle output, or a train of preselected waveforms, depending on the gating signal width and the generator frequency setting.

Key Specifications

Frequency	0.1 Hz to 11 MHz, resolution 10^-4
Frequency stability	≤0.1% for 1 hour, ≤0.5% for 24 hours (ambient +25 °C ±5 °C)
Frequency accuracy	<3% of full scale from 0.1 Hz to 1 MHz. <5% of full scale from 1 MHz to 10 MHz
Output Amplitude	>10 V_p-p open circuit. >5 V_p-p into 50 Ω (@ 10 kHz)
Output Offset	>±5 V_p-p open circuit. >±2.5 V_p-p into 50 Ω
Amplitude flatness	Sine, ±1.5 dB ref. to 10 kHz; Square, triangle ±3 dB referenced to sine
Sine Distortion	< 0.5% from 10 Hz to 50 kHz. Harmonics >30 dB down at all other frequencies
Triangle Symmetry and Linearity	Within 1% from 0.1 Hz to 1.1 MHz, 3% from 1.1 MHz to 11 MHz
Risetime (Square/Pulse)	<20 ns
VCF	10 V signal shifts frequency >1000:1
Ext. Gate	0 to >+2 V, not to exceed +15 V
Trigger Output	>5 V open circuit, >2.5 V into 50 Ω
Functions	Sine, Square, Triangle, + and − Ramp, + and − Pulse

Rear Interface

Output: A28 (GND A27)
Trigger Output: B27 (GND B28)
Gate In: B24 (GND B25)
VCF In: B21 (GND B22)

Repair Issues

Helitrim potentiometers are prone to failure due to cracking plastic axle.
(Tantalum) Electolytic capacitors, especially on the output transistors.
FG502 repair report @ amplifier.cd (German)
Article on Repair of Tektronix FG502 by amplifier.de (English Translation)
The Tektronix Function Generator Teardown - Paul Rako @ electronicdesign.com
For serial numbers below B050740, some FG502's may not shift Output Frequency 1000:1 with 10 V or less as specified. To correct this problem, change R125 from 10 kΩ to 9.41 kΩ.

Pictures

right internal view
left internal view
rear view
front plate