Background

The Tektronix SG5010 is an audio signal generator plug-in for the TM5000 modular test equipment system. It can generate five waveforms: sine wave, square wave, SMPTE/DIN intermodulation test signal, CCIF intermodulation test signal, and sine wave burst. All these signals may be swept in frequency and amplitude. It can generate very low distortion (THD+N < 0.0008%; my own measurements) sine waves from 20Hz-20kHz. It is CPU controlled with selections made via GPIB or front panel keyboard. These characteristics made it very desirable as part of an audio amplifier test lab. These units command a high price: Several working units have recently (Dec 2023) been sold for $USD 1500.

I recently acquired a non-working SG5010 for a good price. This post documents my efforts (ultimately successful) in getting it working.

Tektronix SG5010 Overview

Tektronix SG5010 Front Panel

First … Read More »

The document describes the repair process of a Tektronix CG5001 Calibration Generator. It discusses the errors encountered during the power-up self-test and the components that were found to be faulty. The document also mentions the use of extender cables during the diagnostic and repair process.

Shaun Merrigan investigated Sprague 672D Electrolytic capacitor failures in the HP 70000 MMS test equipment. He found that due to thousands of hours of running time and high internal temperatures, many capacitors have failed. The capacitors made before 1990 are highly prone to failure, while those made between 1990-1999 show signs of aging. He replaced the faulty capacitors with Chemi-Con KYA and KZN series capacitors and all modules are now functioning properly.

The Hewlett Packard 70100A is the power meter module in the HP 70000 modular test system. This post will document a problem common to three 70100A units I have recently restored.

As part of the restoration process, I opened the modules to perform a visual inspection. What I found under the outer cover was this:

70100A PS CPU Board Solder Side Overview before repair

HP 70100A PS CPU Board Deteriorated Rubber Pads

HP 70100A PS CPU Board Deteriorated Rubber Pads

HP 70100A PS CPU Board Deteriorated Rubber Pads

HP 70100A PS CPU Board Deteriorated Rubber Pads

The rubber spacer pads between the circuit boards and the outer metal cover had deteriorated to the point of liquifying and running down board via gravity. All the pads in the three units I examined were afflicted to some degree. Several years ago, I documented a similar phenomenon … Read More »

This post will document my recent repair of a Tektronix 284 Pulse Generator. This device was introduced by Tektronix in 1967. It can produce:

A 50kHz, 200mv fast risetime pulse. Typically, tr < 70 ps

A 100 kHz, 1 MHz, or 10 MHz square wave at 10, 100, or 1000 mV

A 100 MHz or 1 GHz sine wave at 100 mV

The Tektronix 284 can be used to check the risetime of oscilloscopes, (both sampling and real time) amplifiers, transistors, transient responses, and for TDR work. The pulses are generated by a tunnel diode which is a semiconductor device capable of changing states very quickly. Tunnel diodes were invented in the late 1950’s in Japan and widely used in test equipment through the 1970’s. Tektronix used tunnel diodes in “pulsers” like the 284 and many oscilloscopes including the … Read More »

I have recently begun to restore several pieces of Hewlett Packard 70000 Series MMS (Modular Measurement System) equipment. The basic component of the system is a power and/or display frame which can house various test equipment modules. This post documents my restoration of the HP 70001A Power Supply.

The Hewlett Packard 70000 MMS is a high-performance, modular measurement system for RF, microwave, and Lightwave measurements. The MMS instruments include spectrum analyzers, signal generators, power meters, DMM, digital oscilloscope, counter, and more. The system is assembled by inserting the appropriate modules into a mainframe (which supplies power, cooling, and communication) along with a display.

Historically, the 70000 MMS system was introduced in 1986 and continued to be available through at least 2001 (based on HP/Agilent catalogs). The latest prices (1993) I could find for a couple of representative HP 70000 systems follows (all … Read More »

I recently completed the construction of a PC controlled vacuum tester: The Roetest. This is a computer-controlled tube tester which works as follows:

Using the PC software, load the tube data from the extensive database

Verify the tube data and pinout on the screen; the tester configures the pin connections automatically

Run the tests for shorts and filament continuity

Run the required tests

Test the tube at full voltage and current (not a pulse test)

Save the result

Add the tube and test data to inventory

Roetest V10 Front Panel and case

Roetest V10 Main board and plug in boards

Roetest V10 Front Panel

Construction Details:

4600 Solder Joints

600+ Components

20 separate circuit boards

Mechanical work for socket boxes + drilling and tapping heatsink

150+ hours

Using the PC software, load the data for the TUT (Tube under Test). Pinout and base connection information is taken from an extensive database of over 22,000 tube types.

Roetest … Read More »

I have previously written about the substantial number of different modules available for the Tektronix TM500 and TM5000 module plug-in systems. Since the equipment is now anywhere from 20 – 40 years old it needs to be refreshed and/or repaired before going back into service. This often means working on the modules while they are not installed in the power frame:

TM500 Extender Overview: Connects between module and power frame.

TM500 Extender Overview: Connects between module and power frame.

Dan Meeks Extender Closeup. This extender allows monitoring of all supply voltages and currents. It also has LED indicators for each voltage rail.

Extender Plugged into Power Frame

Extender Plugged into module. This allows working on the module outside of the power frame.

From the image above, the extender board projects beyond the edges of the plug-in. This means that the plug in … Read More »

Introduced in 1966, the Tektronix 106 Square Wave Generator is a signal generator which can produce fast rise (<1nS @50 ohm loads positive or negative going) or high amplitude (120 Volts, high impedance load) square waves from 10Hz to 1MHz. It is used for oscilloscope calibration, risetime testing and for triggering extremely fast rise (<100pS) tunnel diode pulsers. The 106 uses a combination of vacuum tube and discrete solid-state technology. This is the sort of equipment that was used for development and testing during the NASA Apollo Program through the 1960’s.

The cost of the Tektronix Type 106 was USD 590 in 1966 or about USD 4900 in 2021 dollars. I was fortunate enough to obtain one of these units in decent condition and I was able to restore it to better than factory specification. What … Read More »

The Tektronix TM5006 is a 6-Bay power frame which can host and power either TM5000 or TM500 plug-ins .

Tektronix themselves had about 130 different plug-ins available which comprised power supplies, signal generators, oscilloscopes, multimeters, test oscillators, calibrators, attenuators, filters, logic analyzers, frequency counters, audio analyzers and more. In addition, numerous third parties made plug-ins for the system. The total number of different plug-ins numbered at least 200. The system was introduced in 1972 and was available in some form through at least 1995. The system is remarkably interesting from a technology standpoint because it encompasses the move from discrete transistor circuitry in early equipment, evolving through microprocessor-controlled units in later equipment. The more modern TM5000 equipment also had network interface (GPIB) capability for control and data acquisition.

In terms of cost, a basic … Read More »

This is an update to my previous post documenting my restoration/repair of two Tektronix Type 114 Pulse Generators. As of this writing I have completed some cosmetic work on the cabinets, front panels and carrying handles of both units. This includes cleaning and painting the cases, cleaning the front panels, knobs, BNC connectors and replacing the missing handle inserts.

Tektronix 114 Handle Insert Bottom Section Missing

Tektronix 114 Handle Insert New Aluminum Base Plates and OEM Example

Tektronix 114 Replacement Inserts and Tolex

Tektronix 114 Replacement Handle Insert and Tolex in place

Tektronix Type 114 Refinished Cabinet and Front Panel

Tektronix 114 Front Panel Cosmetics Completed

I have implemented a Maintenance and Inventory system which includes an equipment label with QR code. The code includes the Equipment Name, Serial Number, Instrument ID Number, and a summary of the latest service work completed on the unit. … Read More »

The Racal Dana Model 9478 Frequency Distribution System has an internal precision, oven-controlled crystal oscillator, or it can be phase locked to an external signal derived from a GPSDO or other master oscillator.  The system will automatically lock to an external signal above 100 mV, and with a standard frequency of 1, 5 or 10 MHz.  “In Lock” indication is provided.

I recently repaired two Racal 9478 units. What I found was widespread electrolytic capacitor failure such as I had never encountered before. A summary of the issues found in both units follows:

Virtually all electrolytic capacitors in both units (nearly 90 in all) had failed, showing either very low capacitance and/or very high ESR. Interestingly enough none showed short circuit failure.All the failed electrolytic capacitors were made by Philips in late 1980’s The -15v regulator was originally bolted … Read More »

The Cubic 3250 VLF-HF receiver is a 10kHz – 30 MHz DSP based radio receiver with 51 IF bandwidths and 7 receive modes. It falls into the category of professional/military grade equipment and the build quality certainly reflects this. According to Fred Osterman’s book, “Shortwave Receivers Past and Present, 3rd Ed.”, it was manufactured from the mid 1990s until at least 1998 (possibly later). I have found that the audio recovery and readability of this receiver is outstanding.

As both of my units were made in 1995/96, they are 25 years old and likely have thousands of hours of use. So I elected to replace all the electrolytic capacitors in the power supply with (arguably) an abundance of caution.

The Cubic 3250 VLF-HF receiver is a 10kHz – 30 MHz DSP based radio receiver with 51 IF bandwidths and 7 receive modes. It falls into the category of professional/military grade equipment and the build quality certainly reflects this. According to Fred Osterman’s book, “Shortwave Receivers Past and Present, 3rd Ed.”, it was manufactured from the mid 1990s until at least 1998 (possibly later). I have found that the audio recovery and readability of this receiver is outstanding.

These receivers have a VFD (vacuum fluorescent display) as part of the front panel/human interface. The VFD in one of my units must have had many, many hours on it because it was quite fuzzy and dim, to the point of being blurry:

Aged, dim, blurry VFD

The old display on the CDR 3250 showed considerable burn in when viewed using … Read More »

The HP3245A Universal Source (datasheet is copyright HP/Agilent) is a precision AC/DC voltage and current source that can provide a wide range of precise and repeatable voltages and currents up to +-100vdc and 100mA dc. It can also provide sine, square and arbitrary waveforms up to 1Mhz and 200vpp. Such an instrument is extremely useful in the lab for calibrating meters, driving current and voltage amplifiers and checking equipment. The particular units I have were built in 1992/1993 which means the electrolytic capacitors are approaching 30 years of age. I had decided to replace the RIFA line filter capacitors in (documented here) both my units and performed routine power rail voltage and ripple checking as part of that. For example:

+5.0840 4.4mv+15.194 30mV+18.625 29mV-18.691 28mV

The other power rails and HV Amp power supply also measured good, using an … Read More »

The BK Precision 879B is a good quality, dual display 40,000 count LCR (inductance, capacitance, resistance) meter with 0.1% basic accuracy. It was first manufactured in 2010 and is still available (2021) for around $420 Cdn. I purchased mine several years ago and find it very convenient and easy to use.

BK Precision 879B

Things I like about the 879B:

Open/short calibration completes very quickly as opposed to the DE 5000Decent quality Kelvin clips and smd tweezers40,000 counts for extra accuracyVery good accuracy when compared to my HP4263ALong battery lifeEasy to use menu system and quick setup

A common problem with these units is the lack of robust input protection. What this means is that if you forget to discharge a sufficiently large capacitor and attempt to test it, you will damage the front end of the meter which will … Read More »

The post discusses the condition of RIFA Y Safety capacitors, which were prone to failure due to a cracked outer case. The issues were reportedly resolved after Kemet acquired RIFA in 2007. However, flawed capacitors remain in equipment older than 2007. The author has replaced many such capacitors in various older equipment, improving their safety and functionality.

I have completed the electrical restoration of one Hickok 209A VTVM. This included:

Replacing all the paper and electrolytic capacitorsReplacing all the carbon composition resistors (most were out of tolerance)Installing a polarized AC plug, line fuse and proper safety capacitorReplacing the meter movement (original was mechanically damaged)Rebuilding and restoring the battery holderBalancing the bridge tube resistorsGiving the unit a full check on all modes and ranges

With all of the above complete I can declare the unit ready to use. The cabinet still needs to be cleaned and refinished, but that will have to wait until warmer weather arrives and I can work outside.

The results of my testing were very interesting. I used my lab equipment (see below) to check the 209A on all of its ranges and modes (with the exception of the decibel range). … Read More »

RIFA Safety Capacitor Failures have been documented by many of us who restore and maintain vintage electronics equipment. One very spectacular failure was caught live here: courtesy Dave Jones of the EEVBLOG. These capacitors were widely used in test equipment manufactured during the late 1980’s through the 1990’s. The consensus is that the capacitors fail because the outer case (presumed to be a type of epoxy) develops cracks which allows moisture to penetrate the body of the capacitor. This leads to internal short circuits which cause the capacitor to fail catastrophically. Because these capacitors are line to ground, they could see line voltage whenever a piece of equipment is plugged in, even when switched off. The crack network can develop to the point where large pieces of the outer case spall off, exposing areas of … Read More »

This is the sixth part of an “N” part series documenting my restoration of the Hickok 209A VTVM, SN 1333254.

Hickok 209A VTVM Restoration Part 6: Component replacement decisions

In this Part 6 of the series I will document the condition of the passive circuit components in the Hickok 209A VTVM, and justify why I decided to replace (or not replace) them.

Initial resistor and capacitor measurements Hickok 209A

Starting with the resistors, I measured 8 initially, and of those 5 were out of marked specification on the high side. One more was right at the high side specification and two were within specification. These were all 5% and 10% tolerance carbon composition resistors. Based on these data, I made the decision to replace all the 5% and 10% carbon composition resistors. I used 1% metal oxide resistors with … Read More »

This the fifth part of an “N” part series documenting my restoration of the Hickok 209A VTVM, SN 1333254. Hickok 209A VTVM Restoration Part 5: Checking the meter movement.

This piece of test gear is all about the large, beautiful meter movement, so I need to determine if this one works properly. What I intend to do is connect the meter to a precision power supply and good ammeter through a current limiting resistor and then determine how the meter responds. The meter is supposed to be a 500uA full scale movement.

Here is the test setup:

Analog Meter Test Instrumentation Setup

A 10kohm limiting resistor is connected in series with the power supply. The power supply is a Tektronix PS5004 and the meter is a Tektronix DM5120.

Full Scale Deflection on the meter was about 497 uA:

Analog … Read More »

This the fourth part of an “N” part series documenting my restoration of the Hickok 209A VTVM, SN 1333254. Hickok 209A VTVM Restoration Part 4: Restoring the battery holder.

In Part 3 of this series I documented the condition of the D Cell battery holder and outlined the restoration plan for the unit. The first step is to remove and restore the corroded battery holder.

Hickok 209A SN 133254 Corroded Battery Holder

Besides the obvious corrosion, the white connecting wire to the negative terminal was corroded under the insulation from the battery spring clip to the switch solder lug. I replaced the entire length of this wire. The other short wire and ring terminal were cleaned as described below.

Hickok 209A SN 133254 Corroded Terminal Wire

The process I used to restore the battery holder:

Desolder the two … Read More »

This the third part of an “N” part series documenting my restoration of the Hickok 209A VTVM, SN 1333254. Hickok 209A VTVM Restoration Part 3, corrosion issues and restoration plan.

As mentioned in Part 2 of this series, a visual inspection of the chassis of the 209A revealed a serious corrosion problem with the battery holder. The corrosion had migrated to the bottom of the case but not to the remaineder of the chassis. There were no batteries in the unit when I received it.

Hickok 209A SN 1333254 Battery Holder Corrosion

Hickok 209A SN 1333254 Battery Holder Corrosion

Hickok 209A SN 1333254 Battery Holder Corrosion

Hickok 209A SN 1333254 Battery Holder Corrosion

From the above images, it is clear that the battery holder will require some corrosion mitigation and restoration. Fortunately, it is restorable as the parts are … Read More »

This the second part of an “N” part series documenting my restoration of the Hickok 209A VTVM, SN 1333254. Hickok 209A VTVM Restoration Part 2, visual inspection.

Outside visual inspection results:

Overall good visual condition outsideMeter appears to move freely and does not stickMeter face is excellent and there are no scratches on the glassMeter bezel is dirty, but does not appear to be corrodedArea of corrosion noted at bottom of caseThe case has some minor paint scuffs and nicks accumulated over the past 60 yearsLine cord appears to be original and looks to be in good conditionHas an original rubber grommet where the line cord enters the caseNo obviously broken parts: lamp, pin sockets, dials are in good conditionHas DC Probe (reads 3.36 Mohms)No AC probe but does have the 4 wire AC probe connectorNo pin tip test … Read More »

This is the first installment in a multi-part series documenting my restoration of a classic Hickok 209A VTVM. First a description and some images:

This is a Vacuum Tube VoltMeter (VTVM) with a nominal 12 Mohm input impedance and one of the largest mechanical meter movements found on commerical/consumer equipment (viewing area about 8.5 inches diagonal). It was produced from about 1947 (earliest direct evidence) to at least 1961 (catalog reference). One of the units I have has 03-09-55 written in grease pencil on the back of the meter movement. The cost in 1947 was (reportedly) $133 USD which is about $1500 USD in late 2018. In comparison, the HP 410A (a lab grade instrument) sold for $245 USD in 1948 or about $2500 USD in late 2016 dollars. So the Hickok 209A was not aimed at the laboratory … Read More »

HP 1340A Display Repair

I purchased a couple of HP 1340A XYZ Displays which I thought would be useful as troubleshooting aids and as graphical displays of CRT technology (oscilloscope clocks, and the like). Upon receiving them, they both worked, but careful visual inspection showed some potentially serious problems. I will document the repair process here.

HP 1340A Overview

HP 1340A Overview

HP 1340A Overview

HP 1340A Overview

HP 1340A Overview

HP 1340A Rear Panel, High Serial Number

Visual inspection of the units revealed the following problems:

Heat damaged A1R81 (both units)Heat damaged A2R13 (both units)Loose mounting hardware and corroded wiring on A2Q2 (one unit)

Heat Damaged Components

LVPS A2Q2 Damage

Heat Damaged Components

A2Q2 is mounted directly to the case for heatsink purposes. The hardware was loose, therefore the transistor effectively had no heatsink. I suspect that it had been running hot for quite some time because the PVC insulation … Read More »

Based on my own observations and reading, the CRT in the HP 3562A is a marvelous piece of engineering. However, it literally fatigues over time and at some point the deterioration cannot be compensated for by the range of adjustments. The solution is to replace the ageing CRT display with a modern LCD. It turns out that SimmConn Labs has such a kit:

http://www.simmconnlabs.com/1401/2501.html

Terry at D-Lab Electronics did a good video on how to replace the original CRT with the LCD Kit from NewScope:

https://youtu.be/WKz7GYBON7g

Terry does a great job of documenting the replacement process, so I will focus on the before/after results. I will start with original CRT images, followed by LCD images and by split screen comparison images. Since I also purchased the RGB to VGA adapter cable from SimmConn, I will conclude with an … Read More »

When doing work on older audio gear it is sometimes necessary to maintain a 600 ohm impedance from, for example, a signal generator to a DUT or a piece of test gear. An easy way to do this is with a 600 ohm terminator. The article will document how I built such a terminator.

First I want to acknowledge the work of ElPaso TubeAmps (David Beard) who covered this very subject several years ago:

https://youtu.be/tIB3U-U29wg

50 ohm and 75 ohm BNC terminators are relatively easy to obtain, but 600 ohm terminators harder to come by. The solution is to build one as follows:

Obtain a suitable 50 or 75 ohm BNC terminator . You need the type which can be opened. One clue is that it may have flats on the end of the barrel which were used during assembly.The … Read More »

Early in 2018, I purchased an HP 3562A Dynamic Signal Analyzer for an excellent price on Ebay. The display looked great and it was physically in good condition. However, the unit failed the power on self test as follows:

HP 3562A Error Message on boot

This error code indicates a ROM IC failure.

HP3562A Diagnostic LED’s indicate Hex code 4 4 (0100 0100)

This code indicates a failure of ROM Chip U105:

HP 3562A Rev B ROM board. The problem ROM chip is the fifth chip down in first column (U105)

HP 3562A ROM Board Rev B

This ROM board is an older version using 32kx8 chips in two groups (Low Byte & High Byte) of 18 chips each. I had access to a second 3562A, and swapping ROM boards confirmed that the ROM board was the problem. Now I needed to:

Locate a suitable set … Read More »

AC Line Voltage 34 Hour Log

I recently updated my iPad Air 2 to iOS 12.1 only to find that it would no longer charge via my computer’s USB 3.0 port. Specifically, I had been using, for many months, a decent quality aftermarket cable to connect/charge the iPad to my PC. There were no issues with charging or connectivity using the same configuration prior to the iOS 12.1 update.

A bit of digging suggested a two-part solution:

Power off and restart the iPadUse a genuine Apple cable

Well, powering off and restarting (using the same aftermarket cable) did not work; the iPad still would not charge. However either changing to a genuine Apple cable or a different aftermarket cable together with a power off and restart, did work. The iPad is now charging normally from the USB 3.0 port on my PC. … Read More »

Ebay IC Tester Instructions

The ubiquitous IC/Component tester found on Ebay usually comes without any instructions or documentation:

The unit I purchased came with a one page, 2-sided photocopy instruction sheet, so I thought I would share it here:

As far as I can tell, this unit will identify and test the following:

Common linear and logic IC’s
Some transistors; seems to be limited to bipolar
Zener Diodes

It does not appear to identify:

LED’s
JFET’s
Three terminal regulators

Thanks for reading,

Shaun M

Tektronix CG5001/CG5011 Pulse Rise Time Measurement

I wanted to measure the rise time of the normal and fast edge pulses in a new acquired Tektronix CG5011 calibration generator.  The equipment line is as follows:

Tektronix TM5006 mainframe

Tektronix CG5011 Calibration Generator

Tektronix CG5001 Calibration Generator

Tektronix/Tegam 015-0611-01 Pulse Head

HP 83480A Communications Analyzer

HP 83483A Electrical Sampling Module (20GHz)

Background:  The original 015-0311-00/01 pulse head was used in combination with the CG551AP and CG5001 calibration generators. The 015-0611-00/01 pulse head is the later version  used on the CG5010 and CG5011 calibration generators.   The primary differences between the later 0611 and earlier 0311 are:

The 0611 has faster edge rise time of <150 ps or < 160 ps for the Tegam version
The 0311 has slower edge rise time  of <200 ps
The 0611 is larger (taller) than the 0311
The 0611 made by Tegam has an SMA output connector
The 611 made by … Read More »

Tektronix 7904A S52 Pulse Response

This post documents my investigations into the following vintage electronic gear:

Tektronix 7904A Mainframe (500 MHz Bandwidth)
Tektronix S52 Pulse Head (tr<25ps)
Tektronix S4 Sampling Head (tr < 25ps)
Tektronix 7S12 TDR/Sampler Plug-in

Here is the test setup:

Tektronix 7904A using 7S12 with S52 and S4 heads. 34ps system rise time. She’s working Captain (MS)

HP 8903B Audio Analyzer PCB Pad Replacement

Visual inspection of my recently acquired HP 8903B Audio Analyzer revealed that the polymer pads on the bottom side of the main PCB were seriously deteriorated:

HP 8903B Deteriorated Pads Overview

HP 8903B Deteriorated Pads Closeup

HP8903B Deteriorated Pad Macro Lifted

Besides making an unsightly mess, this residue may form corrosive products which, over time, could damage the PCB.  Also, the pads no longer perform their bottom cover to PCB isolation function.  So all the old pads and residue had to be removed and new pads installed.  Lintless wipes, isopropyl alcohol, and nitrile gloves were the chosen tools.

HP 8903B partly cleaned PCB

HP8903B Board Cleaned and Pads Replaced Overview

HP8903B Board Cleaned and Pads Replaced Macro

The residue cleaned up completely, and new pads were installed. I won’t need to … Read More »

Tektronix 7854 Waveform Keyboard Rebuild

From the Tek Wiki:

The Tektronix 7854 Waveform Processing Oscilloscope, introduced in 1980, is a 400 MHz combined analog / digital mainframe in the 7000 series that takes two vertical and two horizontal 7000-series plug-ins. In addition to a conventional analog (real time) scope, it contains an equivalent-time sampling 10-bit digitizer and a programmable waveform processor with GPIB interface. The waveform processor can be programmed using a detachable calculator-style keyboard, using postfix operators (“reverse Polish notation” like HP calculators) that operate on entire waveforms, not just individual numbers.

Tek 7854 Mainframe #2 after cleaning

Tek 7854 Mainframe after cleaning

It is to the repair of the detachable keyboard that this post is devoted.  I purchased a keyboard for a reasonable price only to find that some keys were intermittent, and some did not work at all.

Opening up the keyboard showed … Read More »

The uTracer Tube Tester and Curve Tracer

I have completed building my uTracer (micro Tracer) computer based vacuum tube tester and curve tracer.  This unit, designed by Ronald Dekker described on his website:

The uTracer is much more than a simple tube tester; it is also a curve-tracer. It measures both the anode as well as the screen currents for a range of specified bias conditions, and arranges the measurements in meaningful sets of curves. From these curves parameters like the transconductance or the output resistance can then be extracted and plotted as a function of bias. Alternatively the uTracer can be used as a tester which extracts important parameters like Ia, Rp, gm and um in your favorite bias point in a matter of seconds. http://dos4ever.com/uTracer3/uTracer3_pag0.html

Ronald Dekker makes this tester available as a kit, with detailed assembly and testing instructions.  One of … Read More »

Tektronix DSA602A Digitizing Signal Analyzer Part 1

I recently had the opportunity to purchase one of these units, and I am thoroughly enjoying the process of  checking its operation and getting to know how to use it.  This unit is a laboratory grade, very accurate digitizing oscilloscope from about 1990.  From the Tek Wiki entry:

Inputs
3 amplifier bays, up to 12 channels (using 11A34 plug-ins)

Resolution
8 bits; averaging of N acquisitions increases by log2(N) up to 14 bits

Display resolution
50 pixels/Div

Sample rate
DSA601, max 1 GS/s; DSA602, max 2 GS/s (one channel, left plugin)

Record length
512 to 32768 samples

Sweep rate
50 ps/Div  to 100 s/Div

ENOB
7.2 bit up to 10 MHz, 6.3 bit @ 250 MHz, 5.7 bit @ 500 MHz, 4.5 bit @ 1 GHz

Screen
magnetic deflection color computer monitor, 10″ diagonal (130 mm × 168 mm), 552×704 pixels, 22×11 infrared touch-screen grid

Power
90-132 V or 180-250 V, 48-72 Hz, 465 W (DSA601A) / 585 W (DSA602A)

Features

Automated signal measurements (rise, fall, period, frequency, width, delay, phase, duty … Read More »

Tektronix Scope-Mobile Cart Repair Part 3

Part 1

Part 2 

This is the conclusion to my repair of a Tektronix 202-2 Scope-Mobile Cart.  Recall that the problem was three fractured trunnion mount bosses which rendered the cart useless (and unsafe) under load.  My proposed solution was to place the bosses into compression by putting a 6mm countersunk bolt through the trunnion mount concentric with the existing hole in the boss.  By using appropriate sized washers between the top of the boss and the frame member I ensure that the boss is placed into compression and the frame member is securely clamped.  This avoids the tensile loading which fractured the bosses initially.

Trunnion to member closeup with new bolt and washers in place

The holes in the trunnion mount were countersunk to fit the flat head socket bolts:

Countersunk Hole for new bolt

Read More »

Tektronix 556 Dual Beam Oscilloscope Testing: Vertical Bandwidth

I have been doing some basic testing of my Tektronix 556 Dual Beam Oscilloscope, and I have documented some parts of this process.  I have also captured images of the traces, which I will share here.

Test Setup: Tektronix 556, 1A2 plug-in, Timebase A, Tektronix SG 503 Generator, and Tektronix TG 501 Time Mark Generator

I found the -3db vertical bandwidth of the 1a2/556 to be 65 Mhz, which is to be expected for the 50 Mhz rated 1A2.

TM 500 Module with Plug ins

TM 500 Module

50 kHz Reference Signal 6v peak to peak

Tek 556 with 1A2 Vertical 50 KHz BW Test

5 MHz Sine Wave 6v peak to peak

Tek 556 with 1A2 Vertical 5 MHz BW Test

20 MHz Sine Wave 6v peak to peak

Tek 556 with 1A2 Vertical 20 … Read More »

Tektronix 556 Fan Motor Repair Part 2

In this continuation of Tektronix 556 Fan Motor Repair Part 1, I have removed the motor and mount assembly and disassembled it.  Now I need to figure out the problem and rebuild the motor.

Tektronix 556 Fan Motor Overview, mounted in place

556 Fan Motor Rear

Tektronix 556 Fan Motor removed from mounts.  The Tektronix part number is 147-0029-00.

Tektronix 556 Fan Motor

Tektronix 556 Fan Motor removed from mounts.

Tektronix 556 Fan Motor

Tektronix 556 Fan Motor removed from mounts.

Tektronix 556 Fan Motor

The next few images show the disassembled parts of the motor:

Rotor, end bells and bushing assembly

556 Bushing Assemblies and Rotor

End bell inside, retainer, spring washer felt and bushing.

556 Fan Motor Bushing Assembly

End bell and bushing assembly

556 Bushing Assembly

Rotor and spacers

556 Fan Motor Shaft … Read More »

Tektronix 556 Fan Motor Repair Part 1

I was recently fortunate enough to acquire a Tektronix 556 Dual Beam Oscilloscope with many accessories and in good condition.  Unfortunately, the cooling fan on the scope was very loud and more concerning, it emitted an alarming metal on metal contact sound.  After verifying basic operation of the oscilloscope, I decided to repair the cooling fan.  This process is documented in the images and commentary that follow.

Part 1: Removing the Noisy Fan Motor

556 Cooling Module with filter and mesh screen removed.  The fan is connected to the chassis wiring at the ceramic terminal which is circled:

556 Fan Cooling Module Outside

Fan to chassis wiring connection terminal.

556 Fan Cooling Module Fan Connections

Inside of cooling module and bottom side of motor (fan blade removed):

556 Fan Motor Underside

Back side of motor (fan blade … Read More »

Tektronix Scope-Mobile Cart Repair Part 2

This post continues my repair of the Tektronix Scope-Mobile Cart and  trunnion mounts. Here is Part 1, which details the problem and my proposed solution.

The original design used 5/16″ button head bolts which screwed into the bosses and attached the aluminum box frame member to the polymer trunnion mount:

Trunnion to member overview-1

Trunnion to member closeup-2

Trunnion to member closeup with original fastener-3

Trunnion to member closeup with original fastener and cover in position-4

It is obvious that overtightening these bolts put the bosses into tension which caused them to fail.  The gap between the member and the boss “spring loads” the system and puts additional tensile stress on the boss.  While an aluminum casting could easily handle these stresses, the polymer obviously could not.

What I did was to glue the fractured bosses into … Read More »

Tektronix Scope-Mobile Cart Repair Part 1

I was lucky enough to obtain a Tektronix 202-2 Scope-Mobile Cart.

Tektronix 202-2 Scope-Mobile scanned overview image

Upon examining it, I found that the scope tray was loose and the tilt mechanism did not function properly.  The cause for this was broken trunnion mounts on both sides of the cart as follows:

Tektronix 202-2 Mobile Cart Chassis Parts

Trunnion Mount and Broken Bosses Overview

Trunnion Mount and Broken Bosses Overview

Three of the four bosses were fractured with the fracture surface indicating tensile overload.  I suspect that the bolts were overtightened and the bosses fractured. Overtightening loaded the bosses in tension by trying to compress the box frame member.  Unfortunately this type of polymer (some type of hard thermoplastic) is not good in tension.

Other mobile carts I have seen use cast aluminum for … Read More »

New Vacuum  Tube Box Scans

I have uploaded several new vacuum tube box scans including Philco, Canadian General Electric, Wards, and Hitachi (Hit-Ray):

Wards Tube Box_3

Wards Tube Box_2

Wards Tube Box_1

Philco Tube Box_4

Philco Tube Box_3

Philco Tube Box_2

Philco Tube Box_1

Motorola Small Tube Box_4

Motorola Small Tube Box_3

Motorola Small Tube Box_2

Motorola Small Tube Box_1

Lafayette Tube Box_4

Lafayette Tube Box_3

Lafayette Tube Box_2

Lafayette Tube Box_1

Hitachi Tube Box_4

Hitachi Tube Box_3

Hitachi Tube Box_2

Hitachi Tube Box_1

CGE Radiotron Tube Box_2 (4)

CGE Radiotron Tube Box_2 (3)

CGE Radiotron Tube Box_2 (2)

CGE Radiotron Tube Box_2 (1)

Wards Tube Box_4

Thanks,

Shaun M.

Tektronix 556 Dual Beam Oscilloscope

I had recently the unique opportunity to acquire a complete Tektronix 556 Oscilloscope setup.  This comprised the oscilloscope itself, the matching scope cart, original manual, probes and 12 plug-in units.  This in itself is rare enough, but in addition, this particular scope has the optically desirable blue phosphor CRT and Tektronix C-27 Camera Bezel.   This 50 MHz bandwidth oscilloscope was the state of the art when it was introduced in the mid 1960’s: Tekwiki Tek 556

This will be the first of many posts and updates as I work my way through checking and restoring this beautiful scope.

And now some images:

Tektronix 556 Oscilloscope

Tektronix 556 Oscilloscope

Tektronix 556 Oscilloscope

Tektronix 556 Oscilloscope

Tektronix 556 Oscilloscope

Thanks!

Shaun Merrigan

Tektronix Oscilloscopes 7904, 2467B, 2465B at 1GHz

The images to follow show a 1 GHz sine wave (amplitude not changed during the testing) on the following Tektronix oscilloscopes:

Tektronix 7904 with 7A24 vertical (400 MHz) and 7B92A horizontal

Tektronix 2467B (400 MHz scope)

Tektronix 2465B (400 MHz scope)

1 GHz Sine wave input on a Tektronix 7904 with a 7A24 vertical module

500 MHz Sine wave input on a Tektronix 2467B

1 GHz Sine wave input on a Tektronix 2467B

1 GHz Sine wave input on a Tektronix 2465B

1 GHz Sine wave input on a Tektronix 2465B

I have checked the bandwidth of the both the 2465B and 2467B used here, and they meet the 400MHz requirement at -3db (using a Tektronix SG504 with leveling head).  The bandwidth of the 7904 mainframe + 7A24 vertical plug-in used in this … Read More »

Tektronix 7904 Oscilloscope

Here are some images of one 7904 mainframe  with a 7A24 vertical module and a 7B92A horizontal module.  The scope screen shows the pulse from an S52 pulse head; the rise time is about 850ps which translates into a bandwidth of about 412 MHz.  Since the 7A24 plug-in is specified at 400 MHz, this is about right.

Very fast rise time pulse on a Tektronix 7904 with a 7A24 vertical module

This is the same pulse from an S52 pulse head but using an S4 sampling head instead of the 7A24 vertical amplifier

Very fast rise time pulse on a Tektronix 7904 with an S4 sampling head

Shaun Merrigan

Tektronix 7000 Series Equipment

I am doing some testing on recently acquired Tektronix 7000 series equipment.  Involved in these images is a Tektronix 7904A mainframe using a 7S12 TDR/Sampler plug in with an S52 pulse generator and S4 sampling head.

Tektronix 7904A Fast Rise Time Pulse

Tektronix 7904A Fast Rise Time Pulse

The rise time on of the pulse is about 32ps which translates to a bandwidth of about 11 GHz; all this for a few hundred dollars.

Shaun Merrigan

Fallout 4 Vacuum tubes and Nixie tubes

I have been working my way through Fallout 4 and during my explorations I noticed that the labs and military installations are loaded with vintage vacuum tube equipment.  I thought I recognized the front panel of at least one piece of gear:

Front Panel render from Fallout 4 (Bethesda Softworks):

Fallout 4 Front Panel

 Now compare this image with the front panel of the Racal RA-17:

Racal RA17 Front Panel

The resemblance of the Fallout 4 render to the real Racal RA17 is striking.  This Racal-like front panel appears in nearly every lab and/or military installation that I have explored.

Another rack of equipment very frequently seen in labs and military installations is this one:

Fallout 4 Equipment Rack (Bethesda Softworks

Fallout 4 equipment rack

This image clearly shows:

A nixie tube … Read More »

Numitron Clock Project

Numitrons are low voltage incandescent display devices perfected and marketed by RCA (see RCA advert above) in the early 1970’s.  I would call this a bridge technology as the display is incandescent, but can be driven by integrated circuits.   They were quickly displaced by solid state LED (light emitting diode) devices from the mid 1970’s onward.

This is a Numitron:

RCA Numitron Advert

The look and feel of a Numitron display appeals to me and I wanted to reboot my building and soldering skills , so I decided to build a Numitron clock.  I based my clock on the RCA DR2000 which has a beautiful 15mm display height and a board and parts kit (no longer available) from Richard White.  Here are some images of the construction process:

And here is an image series of the finished clock … Read More »

New Vacuum tube box scans

I have added several new images to my gallery of Vacuum Tube Box Artwork.

The new images include Westinghouse, Tung-Sol and Quality Brand tube boxes.

Quality Brand Tube Box Side 2

Westinghouse TV Receiving Tube Box Side (4)

Shaun M

New Section added: Vacuum tube glow, box scans and artwork

In the spirit of both preservation and exploration, I have added a new section to the the under Photography: Vacuum tube glow, box scans and artwork

Here I will be documenting the artwork used on vacuum tube boxes as well as showing some of the images I have captured of vacuum tubes while they are operating.  I will be adding more images over time as I work through my vacuum tube inventory.

12AU7 “Blue Glow”

Cubic Communications CDR-3250 VLF-HF Communications Receiver Fan Noise Solution Part II

This post will furnish additional detail about installing a quieter and more efficient rear panel fan in the Cubic Communications CDR-3250 VLF-HF Communications Receiver.

As I mentioned in the previous post, the duct/standoff/adapter can be made from wood. I chose solid pine because I had some in my offcuts box; plywood would be a good choice too.

The dimensions of the duct are: 75mm H x 60mm W x 15mm D as shown:

The holes are 55mm diameter (fan side) and 45mm diameter (receiver grille side). The hole on the receiver side had to be smaller in order to accommodate the 42mm bolt hole pattern of the OEM fan, while leaving enough material around the fastener holes for a sound mechanical joint. In addition, I happened to have 45mm and 55mm hole saws … Read More »

Cubic Communications CDR-3250 VLF-HF Communications Receiver Fan Noise Solution

I recently had the opportunity to acquire a Cubic Communications CDR-3250 VLF-HF Communications Receiver (two, in fact), fully functional, in very good condition. This is a very high quality, mil-spec receiver using DSP for the final IF, giving a large selection (51 possible, depending upon the mode) IF filters. It is stable, selective and has one of the best menu systems I have used in a receiver. Also the the audio quality and audio recovery is the best I have heard this side of a tube radio like the R390A or SP600JX. Oh yes, stereo headphones work (mono in both ears) properly from the headphone jack.

The receiver incorporates a small box fan in the rear of the chassis to pull air through cooling the modules and power supply (also at the rear). … Read More »