The next best-kept test equipment series

[N8YX]

(Don't worry, Jerry, I'm making my way to the HP stuff. But it'll be their network and spectrum analyzers. ;) )

We've discussed the scope/waveform measurement goodies elsewhere so now it's time to cover the signal source and metrics equipment. The gear I'll describe in this thread is modular in nature, fits into a variety of power compartments (also referred to as mainframes) and comes in many flavors.

Amongst them:

DC power supplies - manual and programmable
Voltmeters - manual, autoranging, autoranging precision, programmable
Frequency counters - manual, autoranging, programmable
AF signal generators - manually tuned analog, low and ultra-low distortion analog, ultra-low distortion synthesized programmable
RF signal generators - manually tuned analog, leveled output HF/VHF/UHF (used for scope calibration), programmable synthesized VHF/UHF
Function generators - arbitrary and fixed-mode - manually tuned analog, manually tuned analog with sweep, manually tuned analog with independent sweep (to 40+ MHz), programmable, programmable arbitrary
Pulse generators - manually tuned analog, HV (80+ Vout) manually tuned analog, independent-mode manually tuned analog, programmable synthesized
Television alignment equipment - raster generators, digital video probes, calibration generators (we'll go over these in depth elsewhere)
Calibration and tracking generators - manually tuned analog, programmable digital CalGens, ramp generators and spectrum analyzer tracking generators for use with the 7L1x series and 49x series were offered
Audio measurement, quantization equipment - distortion/SINAD/THD measurement, audio power level meters
Waveform measurement - a variety of oscilloscopes in 5/10/15/80MHz bandwidths were offered, as was a 2MHz B/W X-Y display
Logic analysis - A few options here, and each requires a scope (internal or external) for display of waveforms. At least one word recognizer was made available.
Miscellaneous plugins - prescalers, receivers, gates, delay lines, time bases and many other types were offered, both from Tektronix and from industry partners such as Tegam, Metrotek, Spectracom, Pulse Instruments, etc. Tektronix also offered a 'roll your own' plugin kit consisting of a case, breadboard and blank faceplate - in both single and double-wide format.

[N8YX]

First off...to power and use any of these you're going to need a way to do so. Fortunately, Fred has spent (the equivalent of) millions of dollars on this stuff so you don't have to "trial and error" your bench.

A foreword about 500 (non-programmable) vs 5000 (programmable) series:

The 5000 series modules - being equipped with a GPIB I/O connector, in addition to multiple power headers - will NOT work in a 500-series mainframe without special modifications. The 500 series modules, however, WILL work in a 5000-series mainframe.

If the only type of equipment you'll be running is the 500 series stuff, you can use any of the TM500 mainframes. They come in 1, 2, 3, 4, 5 (portable) and 6-wide arrangements. The TM5000 frames were offered in 3 and 6-wide variants, along with a few specialty TM5003s which didn't have all power/communications slots populated. These are found as part of the DA4084 and AFG5501 packages; their usability with other 5000 series plugins varies depending on power and GPIB connector location.

So...if you're out scrounging the 'fests and want to run 5000-series equipment, be on the lookout for either of the following. In the case of the 5003, make sure all power slots are populated with connectors:

tektm5006a.jpg

[N8YX]

This is one of the handiest TM-500 power compartments to have. Load it up, fasten the covers on the thing and take along as airliner luggage.

tektm515.jpg

[N8YX]

Some thoughts on plugins, from a user's - not a collector's - point of view:

There are a number of modules which are classified as handy to have, and which weren't widely offered. Several examples are the TVC-501 (time to voltage converter; very useful with a scope plugin for trigger integration), the DA-4084 (incorporates a SINAD test, rather than the AA-501/AA-5001's THD+N test...ideal for communications receiver repair) and the word recognizer for the LA-501. A judicious shopper can still nab these for decent prices.

A little more up the pricing ladder but still fairly common are the SG505/WR/WQ audio oscillators, and the AF501 tunable filter/oscillator. A set of 505's (ideally, a Mod WQ/WR pair) is a must for audio power amplifier IMD testing and the asking price for these instruments reflects their demand. Even so...it's easy to find a stand-alone instrument whose performance meets or exceeds their claimed .002% THD. Thus, go for the better deal.

The synthesized variant is known as the SG-5010. Folks, there's no way in hell one of these is worth the $800-2000+ being asked by some equipment vendors...but we've only begun to scratch the surface of "ludicrous".

Presented for your consumption is the following:

http://www.ebay.com/itm/TEKTRONIX-TM...item3f1e6cc143

A "Best offer" of $300 is being damn generous, and the seller countered with a $550 offer.

FWIW, here's what one can get for that amount of money:

http://www.ebay.com/itm/Tektronix-24...item5aee1d24d9

4 channels of 400MHz goodness and GPIB programmable to boot. The 2400 series is a fine array of equipment.

So...Rule #1 when shopping for TM-50xx stuff is to never pay more for a module than an equivalent piece of gear (which is most times functionally superior) will fetch.

[N8YX]

And now a word about calibrators and generators.

First, NTSC analog-only stuff. Can anyone tell me why the following purveyor should put the pipe down?

http://www.ebay.com/itm/Tektronix-06...item45fee46916

A few similar items are listed from time to time and I'll update this accordingly.

Next - WWVB changed formats in 2012; their new phase-modulation scheme means that equipment manufactured prior to the changeover - such as these examples from the 80s and 90s - will not decode the time data properly. In fact, they won't even go into phase lock:

http://www.ebay.com/itm/SPECTRACOM-M...item337e596d6e

http://www.ebay.com/itm/Tektronix-TM...item35b3d62c0c

The last one is laughable. One wonders if the seller is aware of the fact it doesn't function as intended...

[AE1PT]

Nice series of posts, Fred. I have been thinking about the Tek mainframe series as a replacement for my 465B--and rolling that over to monitor service in the OP section of the shack. And I agree that the prices are insane...

From practical knowledge, I know that these equipment recyclers pay nearly nothing for the used equipment. It is most often bought by the pallet from universities as 'surplus', and by lots in liquidation sales from corporations that are downsizing or have become defunct. I miss the surplus warehouse at the University of Kentucky--I built a whole research center from the ground up with 'discards' from other departments. Everything from furniture on up. There was a mass spec unit I wanted to carry away but could not rationalize who would maintain and operate it... Everything was free for internal university transfer to one's inventory list.

Pennies for things, literally--by the pound or shrink wrapped pallet--and then they tack outrageous prices running into thousands of dollars. Sometimes if one bids often enough on many things good deals are still had. My Gigatronics and Advantest gear are examples of that. But most of it? Do these guys actually sell this stuff at these prices or does most of it end up in foreign markets at half the price?

[N8YX]

But most of it? Do these guys actually sell this stuff at these prices or does most of it end up in foreign markets at half the price?

I'm really beginning to think not, Pat. There's that whole "certification" bit: A lot of these so-called 'calibration labs' buy the stuff for pennies on the dollar, "calibrate" it then pass the savingsexorbitant lab fees onto prospective buyers.

One of the very first things I did when acquiring the Tek gear was to fork out the money for any required test fixtures, harnesses, extenders and calibration generators. The calibrators can be sent in for their yearly certification (if one gets overly anal about such matters) then used to repair anything else which makes its way across the bench.

Continuing the display of sheer eBay ludicrousness, the following is presented for consideration:

http://www.ebay.com/itm/Tektronix-SG...item20cf06b756

Did I mention that the unit requires a leveling head? They've been priced anywhere from $300-500. Whether or not they're actually being sold is another matter entirely.

You use a leveled signal generator to adjust gain compensation on a scope's vertical amplifier, and a '504 touts an output which is flat to within 1/2dB or so across the tuning range. Those scopes which offer bandwidth coverage into the GHz region must be checked with this type of a setup.

Back in December I managed to get hold of a like new '504 complete with head for $250. Due to miscommunication on delivery addressing, the seller and I chased the thing around for about a month. He even threw in a free Tek scope probe when it landed back at his shop.

The deals are out there - but unfortunately, so are the sellers.

[N8YX]

Onto today's TM500 plugin. It's by far the most common one available - was made for many years - and shouldn't fetch more than a hundred bucks even in 'NIB' condition:

The AM503 current probe amplifier. You use this in conjunction with a 20A clamp-on probe (pricy) or a large, 100A clamp-on probe (pricy ^2) and an oscilloscope. The scope's vertical deflection becomes a representation of the current flowing through the connector around which the probe is clamped.

Handy for automotive wiring and automation control systems troubleshooting. Damned handy, but not $1000 worth of handy (probes not included) which some eBayers think they can get for one. Hamfests or general electronics fleamarkets along with government auctions are your best bet for snagging one of these.

[N8YX]

Okay...let's put some measurement setups together. These are going to consist of both analog and digital arrangements, from the simplistic to the esoteric.

First is one which most communications electronics enthusiasts (ham, SWL, CB or scanner listener alike) will make immediate use of: A DMM/frequency counter combination. I am going to start by discussing counters in general and specifically mentioning a few wonderful counter modules which use the same (now unobtanium) Litronics DL-883A readout:

DC-503 (100MHz)
DC-508 (1GHz)
DC-508A (1.3 GHz)

All are great counters. Occasionally, a digit segment in the -883A (or the -882 2-digit devices used in the '503) will go bad. The original readouts are scarce but one can rob a working readout from an otherwise junk counter. Make sure to test a prospective unit before buying. When the counter is powered up, pressing its front panel 'Reset' switch will tell you everything you need to know about the entire display; should see a nice set of 8s.

(I would use a broken '503 to repair a display-defective '508x - not the other way around. The '508s are far too nice of a counter to relegate to the scrap heap. And a couple of us are working on a replacement readout for these units...IF we can find modern-day 3 digit readouts of a small enough form factor.)

That leaves us with a few remaining choices. My recommendations if using a TM500 series power module:

DC-502 (55MHz/550MHz pre-scaled)
DC-503A (125MHz)
DC-504A (100MHz, high-resolution)
DC-505A (225MHz)
DC-509 (135MHz) - can be used with /10 prescaler
DC-510 - same as the DC-5010 listed below but non-programmable; will work in a TM500 power module.

If using a TM5000 series module and space is limited, choose one of the following single-width programmable counters:

DC-5004A (100MHz)
DC-5009 (135MHz) - can be used with /10 prescaler

If, on the other hand, you aren't space constrained go straight for a DC5010. It's a two-channel, 350MHz counter which is adequate for almost every need the HF-focused ham/SWL can throw at it.

Should one need accuracy into the GHz region and want to keep things modular, you have a couple options. One is a DC508/508A unit. Another is the '509/'5009 unit with a DP-501 Prescaler ahead of it. Yet another approach (and one I would definitely consider) is to roll your own /10 prescaler and fit it into a defunct TM series module case.

(I'll cover "u-build-m" Tek TM constructs much later in this thread.)

tekdc5010front.jpg

[N8YX]

On to DMMs.

Almost all of these are single-width units and will work in both the TM500 and TM5000 series power units. A few have temperature measurement capabilities.

DM-501A (4 1/2 digit, voltage/current, resistance, temperature, dB-rms)
DM-502A (as above; 3 1/2 digit)
DM-504A (4 1/2 digit, voltage/current, resistance, dB-rms)
DM-511 (as above)

For TM5000 power units the following programmable multimeters are available:

DM-5110 (equivalent to a DM-511)
DM-5010 (as above, with Math functions; double width)
DM-5120 (6 1/2 digit high-precision; triple-width)

tekdm5120front.jpg