The Tektronix 3L5 is a 50 Hz — 1 MHz spectrum analyzer plug-in for 560-series scopes.
It is very similar to the 1L5 and can be used to measure the spectrum of signals. In conjunction with the 015-0107-00 "Swept Frequency Generator" (tracking generator), the 3L5 can also be used to make scalar frequency response measurements. A video filter switch was added to the later SNs (1971 Catalog). 3L5 is based on the swept-frontend design, where the first local Oscillator is swept for the spectrum scan. It is a full semiconductor design except for the final output amplifier, which uses a 8416 vacuum tube.
75 Ω Version
There is also a 75 Ω version of the 3L5. Its input is on the rear, via a coaxial connector. A lever on the front panel switches between two frequency ranges:
- 10 kHz - 1 MHz
- 18.010 MHz - 19 MHz
3L5 requires a timebase plug-in in the horizontal compartment to operate. Timebase plug-in units with serial no listed and below require modification 040-0413-00 to provide the sweep signal to the 3L5 (To pin 18 of the plug-in connector).
|Center Frequency Range||50 Hz to 990 kHz|
|Dispersion Range||10 Hz to 100 kHz|
|Input Impedance||≈ 1 MΩ // 30 pF|
|Input Voltage||Max. 300 V (DC + peak AC)|
|Vertical Resolution||Video - .1 v/div to 100 v/div, LIN - .001 V to 2V RMS|
|Internal Cal Signal||5 kHz ±1%|
|First LO Out||≥1 MHz (Sweep), ≥1 Vp-p into ≥1 kΩ|
|Recorder Out||5 mV to 15 mV into 600Ω|
1 MΩ version
75 Ω version