7D15

Manuals – Specifications – Links – Pictures

The Tektronix 7D15 is a 225 MHz frequency counter plug-in for 7000-series scopes, introduced in November 1972.

The 7D15 is optimized for timing measurements, having a 100 MHz oscillator and interval measurement averaging capability. It has two inputs and can measure frequency, period or time difference.

The front panel uses SMB connectors for arming, clock in/out and reset signals. The arming input for channel A is active-high whereas that for channel B is active-low. When one or both are connected to the scope's delayed gate output, the delayed timebase can be used to select the part of the signal to be counted, e.g. for burst or A-B interval measurements. With this connection, the arming interval is directly visible as the intensified trace in the "A intensified by B" display mode.

When installed in a horizontal plug-in bay, the 7D15 can use the mainframe's trigger signal as its input. In a vertical bay, it can display the gate signal. In "true gate" mode, this is the actual counter gate, however, this has a low repeat rate due to the counter's dead time. The "pseudo gate" mode improves this by showing the gate whenever the arming and trigger conditions are met, whether the counter is active or not. A third mode shows channel B's gate. The gate display signal is also available on a dedicated BNC output that can be routed to a scope input when the 7D15 is installed in a H slot.

Key Specifications

	— Frequency Mode —
Input frequency	DC to 225 MHz
Resolution	0.1 Hz min.
	— Period Mode —
Range	10 ns to 105 s, Averaging ×1, ×10, ×100 or ×1000
Resolution	10 ps max.
	— Time Interval Mode —
Range	6 ns to 105 s, Averaging ×1, ×10, ×100 or ×1000
Resolution	0.1 ns usable
	— Frequency Ratio Mode —
Range	10-7 to 104
	— Totalize Mode —
Range	0 to 108 counts
	— Manual Stopwatch Mode —
Range	0 to 105 seconds
	— Inputs CH A + CH B —
Frequency Range	DC (AC coupled: 5 Hz) to 225 MHz
Sensitivity	100 mVp-p (from TRIG SOURCE: 0.5 Div)
Max. input	200 V DC linearly derated to 20 V at 200 MHz
Min. pulse width	5 ns
Input impedance	1 MΩ // 22 pF

Internals

The 7D15 uses a number of Tek-made custom chips. The 155-0086-00, 155-0087-00 and 155-0088-00 legend generators are specific to this plug-in. The 155-0090-00 or 155-0171-00 four decade counter/latch/DAC chips implement the lower six counter digits. For the topmost two digits, the 7D15 employs ECL counters. ECL logic requires a −5 V supply, which a switching regulator (board A8) generates from the −15 V rail.

The 5 MHz signal from the (non-ovenized) internal reference crystal oscillator is divided down to a 1 MHz master clock. Optionally, the 1 MHz can be supplied externally as well. An internal VCO, phase-locked to the 1 MHz master, produces a 100 MHz input to the counter chain for timing measurements.

Links

• Tekscope Vol. 4 No. 5, 1972: The Oscilloscope Controlled Counter
• TekScope Vol. 7 No. 5, 1975 p.15+: Dave McCullough, Delayed gate aids oscilloscope digital measurements
• 7D11 and 7D15 Marketing Sales Release
• Tek 7D15 page @ amplifier.cd
• Tek 7D15 page @ barrytech.com
• Tektronix 7D15 Repair and alignment by Zenwizard Studios @ YouTube

Documents Referencing 7D15

Document	Class	Title	Authors	Year	Links
Aug 11 1972 7d11 7d15 marketing sales release.pdf	Article	7D11+7D15 Marketing Sales Release		1972	7D11 • 7D15
Tekscope 1972 V4 N5 Sep 1972.pdf	Article	The Oscilloscope-controlled Counter	Neil A. Robin	1972	7D15
7000 series brochure March 1973.pdf	Brochure	7000 series brochure, March 1973		1973	7A11 • 7A12 • 7A13 • 7A14 • 7A15A • 7A16A • 7A17 • 7A18 • 7A19 • 7A21N • 7A22 • 7B50 • 7B53A • 7B70 • 7B71 • 7B92 • 7CT1N • 7D11 • 7D13 • 7D14 • 7D15 • 7M11 • 7L12 • 7S11 • 7S12 • 7T11 • 7704A • R7704 • 7904 • R7903 • 7603 • R7603 • 7403N • R7403N • 7313 • R7313 • 7613 • R7613 • 7623 • R7623 • P7001
Tekscope 1975 V7 N5.pdf	Article	Delayed Gate Aids Oscilloscope Digital Measurements	Dave McCullough	1975	7D12 • 7D14 • 7D15 • 7B53A
7000 Series Digital Plug-In Applications.pdf	Application Note	7000 Series Digital Plug-In Applications		1977	7D10 • 7D11 • 7D12 • 7D13 • 7D14 • 7D15
AX-3957.pdf	Application Note	X-Y Displays with Interval Timing for Measuring SOA		1979	7D15 • 7A17
42W-5017.pdf	Application Note	Increased Measurement Accuracy Using a 7D15 Universal Counter/Timer in any 7000 Series Oscilloscope		1982	7D15
42W-5588.pdf	Application Note	Advanced Triggering Techniques	Roger Ensrud	1984	7A42 • 7D11 • 7D15

Prices

Year	1973	1976	1980	1984	1990
Catalog Price	$1,475	$1,600	$2,200	$3,200	$4,400
In 2023 dollars	$10,000	$8,500	$8,100	$9,300	$10,200

Pictures

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  7D15 front

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  7D15 left side. Note -5 V switching regulator (board A8) on the far left.

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  7D15 right side

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  Cam switch with contacts on both sides of the PCB

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  double-sided switch

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  double-sided switch

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  double-sided switch, bottom-side contacts

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  double-sided switch, through-board pins

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  7D15 powered on

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Components

Some Parts Used in the 7D15

Part	Part Number(s)	Class	Description	Used in
155-0086-00	155-0086-00	Monolithic integrated circuit	custom legend generator	7D15
155-0087-00	155-0087-00	Monolithic integrated circuit	custom legend generator	7D15
155-0088-00	155-0088-00	Monolithic integrated circuit	custom legend generator	7D15 • 7L13 • 7L14
155-0090-00	155-0090-00 • 155-0090-01 • 155-0090-02	Monolithic integrated circuit	four-decade counter, latch and D/A converter	7B85 • 7D01 • 7D12 • 7D15 • 7J20
155-0171-00	155-0171-00	Monolithic integrated circuit	four-decade counter, latch and D/A converter	7B85 • 7D01 • 7D12 • 7D15 • 7J20
2N3958	151-1054-00 • 151-1054-01 • 151-1054-02	Discrete component	dual n-channel JFET	FG503 • MR501 • M3 • PG505 • SC501 • SC502 • SC503 • SG502 • 1450 • 1501 • 1502 • 1503 • 221 • 5A23N • 5CT1N • 577 • 603 • 603A • 604 • 604A • 605 • 606 • 606A • 606B • 607 • 607A • 620 • 624 • 7CT1N • 7D15 • 7D20 • 851