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Tektronix 7L18
18 (60) GHz Spectrum Analyzer
Tektronix 7L18

Compatible with 7000-series scopes

Produced from 1978 to 1984


Manuals – Specifications – Links – Pictures

The Tektronix 7L18 is a spectrum analyzer plug-in introduced in 1978 for 7000-series scopes. It occupies three plug-in bays in the oscilloscope.


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The 7L18 covers the range from 1.5 GHz to 18 GHz with the internal mixer and 12.5 GHz to 60 GHz using external mixers. Note that it will NOT do 1.5 GHz to 18 GHz in one span, it will only max span the range selected by the BAND/HARMONIC control. This range is determined by the heterodyne harmonic number and sign (sideband) and the range of the first LO, which is 2 GHz to 4 GHz.

The input attenuator range is 0 dB to 60 dB in 10 dB steps and is a standard Weinschel Engineering product driven by a belt. The range is encoded for the digital dBm reference level display. The signal then passes through a YIG preselector filter with a 50 MHz bandwidth. After the YIG filter, the signal enters the RF input of the mixer assembly.


Linley Gumm says:

Another disappointment was the 7L18 microwave analyzer project, one of the earliest Tek products to have a microprocessor in it.

"We started work on developing this product in 1974, and finally shipped our first instrument in 1978. As I look back, it was a terribly crude microprocessor, and we made every error in the book. Of course, we didn't have any of the tools that are available today."

Although the 7L18 never did sell well, Linley and his crew developed components and technologies that later were used in the 492. (TekWeek March 27, 1987)


The LO is a YIG tuned oscillator covering the 2 GHz to 4 GHz range. Its output passes through a sampler assembly used to PLL the YIG on small resolution bandwidths. The output of the sampler goes to the LO input on the mixer. The mixer IF output is 510 MHz.

The 7L18's components are controlled by an Intel 4004 4-bit microprocessor.



Service views:

Boards within the digital card cage (from back to front):

The microcomputer board is built using three very old Intel chips: an Intel 4004 processor, an Intel 4002 320-bit RAM and 4-bit output port, and an Intel D4289 standard memory interface. The D4289 connects the 4004 to the two 2K8 ROMs. Note that in an earlier version of the 7L18 there were 6 ROMs.

Internal views of the analog parts:

Custom ICs used in the 7L18

Page Class Manufacturer Model Part nos Description Designers Used in
155-0035-00 Monolithic integrated circuit Tektronix M053B 155-0035-00 155-0116-00 quad op-amp Mike Metcalf 3110 3S7 3T7 4010 4011 4012 4013 7L5 7L12 7L13 7L14 7L18 7S11 7T11 7S12 S-6 1461 4602 P7001 613 653
155-0056-00 Monolithic integrated circuit Tektronix M042E 155-0056-00 sweep control Val Garuts 26G1 26G2 26G3 314 4701 5B10N 5B12N 7L5 7L12 7L13 7L14 7L18 7S14 5S14N RG501 Telequipment D63 Telequipment DM63
155-0157-00 Monolithic integrated circuit Tektronix M180 155-0157-00 digital storage vertical control Don Kirkpatrick 7L5 7L14 7L18 491 492 492A 492BP 492PGM 494 494A 495 496 497P
155-0158-00 Monolithic integrated circuit Tektronix M181 155-0158-00 digital storage horizontal control Don Kirkpatrick 7L5 7L14 7L18 491 492 492A 492BP 492PGM 494 494A 495 496 497P