If you want one used scope for a general hobby bench, our pick is a Tektronix 2465B. It has four channels, 400 MHz of bandwidth and on-screen cursors, and it's one of the last analog scopes built to be repaired from a full service manual. If you want something simpler to learn on and fix, the 465 is the classic first scope. If you need to catch a one-off event, take automatic measurements or pull waveforms into a computer, you want a digital storage scope, and the TDS3054B is easier to live with than a TDS 540.
Analog or digital storage
An analog scope like the 465 or 2465B sweeps an electron beam across a CRT in step with the signal. You see the waveform live, with no sample rate or record length to think about, and a repeating signal looks smooth and natural. What it can't do well is hold on to something that happens once. A fast single event flashes across the screen and it's gone, unless you're using a 2467B, whose micro-channel plate CRT is there to make fast sweeps and one-shot signals bright enough to see.
A digital storage scope samples the signal, stores the points and draws them on a screen. That lets it freeze a single event, measure it for you and send the data to a PC. The limit is how fast it samples. The TDS 540 does 1 GS/s on one channel, 500 MS/s with two and 250 MS/s with all four running, so a single-shot capture on four channels has far fewer points to work with. The TDS3054B samples at 5 GS/s on each channel, which makes it the better single-shot scope of the two.
Tektronix 465 and 465B
Tektronix introduced the 465 in November 1972 and built it until 1983. It's a two-channel, 100 MHz portable with two time bases for delayed sweep, all solid-state except the CRT, with a voltage selector that covers 110 to 240 V mains. The 465B arrived at the turn of the 1980s with the same base specs and improved performance. There was never a 465A. You'll also see the 465M, the commercial version of the AN/USM-425 military scope, which uses soldered rather than socketed semiconductors and lives in a 455 cabinet, and the DM44, a multimeter option that fits on top of the scope.
They're simple and well documented, but old. Shorted tantalum capacitors are a known failure, and on most units the electrolytic filter capacitors in the power supply are old enough to be suspect. Neither version has an on-screen readout, so you read volts and time from the graticule and the knob settings.
Ask for a photo of a clean trace on both channels, plus one with the delayed sweep running, to show the second time base works. Look at the CRT for burned spots, and for a trace that's dim or fuzzy at normal intensity. Ask what the voltage selector is set to and whether the supply has been recapped.
Tektronix 2465B and 2467B
The 2465 family is where Tek's analog portables got a microprocessor. The 2465 arrived in 1984 at 300 MHz, the 2465A in 1986 at 350 MHz, and the 2465B at 400 MHz in the late 1980s. It has four channels, sensitivity down to 2 mV/div, switchable 50 ohm or 1 megohm inputs, and an on-screen readout with delta-volts and delta-time cursors. The 2467B is the same idea with the micro-channel plate CRT, which is what you're paying for if you chase fast single events.
Options change what a 2465B can do. Option 06 adds the counter/timer/trigger, usually called CTT, for precise time-interval, event and frequency counting. Option 09 is option 06 plus a word recognizer probe, option 10 is GPIB, and option 05 adds TV sync. Match the option numbers in the title to what you can see in the photos.
Three faults are well known. The calibration constants, the last setup and even the running hours live in a Dallas DS1225 battery-backed memory chip, soldered to the A5 board without a socket. Its battery was only guaranteed for 10 years, and when it goes flat the scope needs a full calibration. Later production 2465Bs also used surface-mount electrolytic capacitors on that A5 board that leak and corrode the tracks around them. And an IC on the same board, U800, runs hot with very little heat sinking.
Ask the seller whether the DS1225 has been replaced, socketed or backed up, and whether the A5 board capacitors have been done. Ask for a photo of the screen a minute after power-on, with the readout showing and a trace on each channel. A scope that has lost its memory can still show a trace, but its calibration is gone until someone recalibrates it.
Tektronix TDS 540 and TDS3054B
The TDS 540, introduced in 1992, is a four-channel, 500 MHz digital storage scope with a CRT display and GPIB as standard. Record length runs from 500 to 15,000 points, or 50,000 with option 1M. Option 13 adds RS-232 and Centronics ports and option 05 adds a video trigger. Tek followed it with the TDS540A, B, C and D, which changed the acquisition hardware and firmware along the way, so check which letter a listing really is. The common failure on early TDS-family scopes is surface-mount capacitors leaking corrosive electrolyte onto the boards. Ask whether the boards have been recapped, and look for crusty joints around the capacitors in any inside photos.
The TDS3054B belongs to the TDS3000 family, which started with the original TDS3054 in 1998. It's a 500 MHz, four-channel portable that samples at 5 GS/s on every channel, with a 10,000-point record and a color VGA LCD. Ethernet and a Centronics printer port are standard on the B, along with a floppy drive. GPIB, RS-232 and a VGA output come from the TDS3GV communication module, and extra functions come as plug-in application modules such as TDS3AAM advanced analysis, TDS3LIM limit testing and TDS3VID extended video. The TDS3BATC lithium-ion pack runs it for up to three hours, and it weighs 4.5 kg with the battery in. The later C version swapped the floppy for USB storage and dropped the parallel port.
With a TDS3054B, the modules decide what you're buying. Ask for a photo of the module slots and the rear panel so you can see which application and communication modules are fitted, and whether the battery pack comes with it. Then ask for a photo of the screen after power-on with all four channels on.
Which one to buy first
- To learn and to repair, a 465 or 465B. Buy one that has already been recapped, or plan to do it.
- For a general bench, a 2465B. Four channels, 400 MHz, cursors and a readout make it a scope you'll use every day. Favor one with a fresh or backed-up DS1225 and the A5 capacitors done.
- For fast single events on an analog screen, a 2467B. Buy it for the CRT. If you never look at one-shot signals, the 2465B does everything else.
- For saving waveforms, automation and single-shot digital capture, a TDS3054B. It samples faster on all four channels, and Ethernet is standard. A TDS 540 makes sense when you want GPIB and a big CRT and the boards have been recapped.
Checks for any classic Tek scope
A title that says "calibrated" proves little on its own. What counts is a dated certificate from a named lab, with the measured data. Our calibration guide explains what each kind of paperwork is worth. Probes rarely come with these scopes, so plan for a set if the photos don't show any.
Ask how the scope will be packed. These are heavy, and a CRT neck, a bent BNC or a snapped knob is the usual shipping damage. Double boxing with plenty of foam is what you want to hear. Check the mains voltage setting on arrival before you plug in, especially on a unit shipped from a 230 V country. Our eBay red flags guide covers the listing tells that apply to all bench gear, and the first bench build order shows where a scope fits among your other buys.
For more, see every oscilloscope we cover, the Tektronix page, or browse the whole catalog.
