From TekWiki
Jump to navigation Jump to search
Tektronix 7L18
18 (60) GHz Spectrum Analyzer
Tektronix 7L18

Compatible with 7000-series scopes

Produced from 1978 to 1984

ROM Images
File Pos. Checksum
(All manuals in PDF format unless noted otherwise)
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.

Key Specifications

Frequency range 1.5 GHz to 18 GHz with the internal mixer, 12.5 GHz to 60 GHz using external mixers
Frequency span 0; 200 Hz/Div to 500 MHz/Div in 1−2−5 steps; Max (see note below)
Resolution bandwidth 30 Hz to 3 MHz in decade steps
Vertical scale 10 dB/Div, 2 dB/Div, or linear
Input attenuator 0 dB to 60 dB in 10 dB steps
Sweep 1 μs/Div to 20 s/Div, auto, ext, or manual
Digital functions two memory banks (A, B); Display A, B - A saved, peak hold

Please expand


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)

As Project Manager for the 7L18 I would like to express my thanks to those who contributed so much to the success of the project. Bob Bales worked on the sweep, span attenuator, YIG driver, and instrument-interconnect; Russell Brown and George Maney did the microprocessor programming; Carlos Beeck and James Wolf mechanical design of the microwave assemblies, with Dave Shores and Philip Snow providing the electrical design; IF design was done by Wesley Hayward; Jack Reynolds was involved in the early design of the phase lock circuitry with Steve Morton completing the work; Don Kirkpatrick designed the digital storage ICs with Dennis Smith doing the front panel and digital storage board; Al Huegli was responsible for the outstanding job of mechanical design. Virginia Morehead was indispensable in providing prototype support, as were the plant support people during introduction. Many other names should be included in this list but space doesn't allow.

(Tekscope 1977 V9 N3)


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.

The 7L18 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 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.


Documents Referencing 7L18

Document Class Title Authors Year Links
Tekscope 1977 V9 N3.pdf Article Digital Storage for a Microwave Spectrum Analyzer Dennis Smith Don Kirkpatrick 1977
Tekscope 1977 V9 N3.pdf Article A Phase Lock Stabilization System for 30 Hz Resolution at 12 GHz Morris Engelson Steve Morton 1977
Tekscope 1977 V9 N3.pdf Article A High Performance Transportable Microwave Spectrum Analyzer Linley Gumm 1977


Year 1978 1980 1982 1984
Catalog price $12,600 $14,600 $17,500 $19,400
In 2023 Dollars $59,300 $54,400 $55,700 $57,300


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:


Some Parts Used in the 7L18

Part Part Number(s) Class Description Used in
155-0028-00 155-0028-00 155-0028-01 155-0042-00 155-0042-01 155-0042-02 155-0042-03 Monolithic integrated circuit Miller integrator and delay pickoff 5030 R5030 5031 R5031 1401 1401A 1480 1481 1482 1485 26G1 26G2 26G3 314 335 432 434 4701 5B10N 5B12N 5B31 5B40 5B42 5S14N 7B52 7B53A 7B53N 7L12 7L13 7L14 7L18 7S14 AN/USM-281C RG501 Telequipment D63 Telequipment DM63
155-0035-00 155-0035-00 155-0116-00 Monolithic integrated circuit quad op-amp 3110 3S7 3T7 492 492A 492AP 492P 494 494P 496 496P 4010 4011 4012 4013 7L5 7L12 7L13 7L14 7L18 7S11 7T11 7S12 S-6 1461 4602 P7001 613 653
155-0056-00 155-0056-00 155-0056-01 Monolithic integrated circuit sweep control 26G1 26G2 26G3 314 4701 5B10N 5B12N 5S14N 7L5 7L12 7L13 7L14 7L18 7S14 5S14N RG501 Telequipment D63 Telequipment DM63
155-0157-00 155-0157-00 Monolithic integrated circuit digital storage vertical control 7L5 7L14 7L18 491 492 492A 492BP 492PGM 494 494A 495 496 497P
155-0158-00 155-0158-00 Monolithic integrated circuit digital storage horizontal control 7L5 7L14 7L18 491 492 492A 492BP 492PGM 494 494A 495 496 497P
Fairchild 3814 156-0306-00 Monolithic integrated circuit 4½ digit dual-slope DVM controller 7A13 7L13 7L18 DM501
Intel 4004 Monolithic integrated circuit 4-bit microprocessor 7L18