- E5071C ENA ⇒ Agilent (Keysight) ⇒ Network Analyzer
- CMA3000 ⇒ Anritsu ⇒ All-In-One Field Tester
- E4440A ⇒ Agilent (Keysight) ⇒ Spectrum Analyzer
- N9010A EXA ⇒ Agilent (Keysight) ⇒ Signal Analyzer
- 805C ⇒ Agilent HP ⇒ Slotted Line
- TDS1012B ⇒ Tektronix ⇒ Digital Storage Oscilloscope
- 85052B ⇒ Agilent (Keysight) ⇒ Standard Mechanical Calibration Kit
Do you ever find that because some equipment model numbers are so ubiquitous, when you search for them on your favorite search-engine or on Used-Line, they will return way too many results, most of them will not be connected to what you had in mind, and the model you were trying to find will only show up on page 7 of the results?
Of course, if you search for model Z3RA29-56L3 (not a real model number as far as I know), you are very likely to find what you are searching for on page 1 of 1. However if you search for model 123 (this is a real model number) on Used-Line, 300+ results could be returned, with a very low relevancy in terms of your personal search. The reason: Many manufacturers name their equipment models using numbers that include 123 in this exact sequence. Examples: 123, 12338, 1232A, 1230T, 123R, SPS-1230, 102-123, and so on.
As you must realize, searching for a model number made up of numbers exclusively – no letters – makes matters worse. The descriptions and synopses that accompany your results may contain your model number in a price tag or even in a specification. Take a look at this Used-Line listing for a Tektronix 492 spectrum analyzer, which showed up in the results of my search for a 123 Fluke ScopeMeter.
Do you see why my search pulled in this listing? The amplitude range is –123 dBm to +40 dBm.
So, what to do about this?
Well, you can code some new search algorithms and send them along with your resume to the recruiting department of your favorite search-engine.
Or, you can fiddle with various settings in your search engine to train it to guess what you are looking for. And, of course, in some search engines, you can use an advanced search function to search for an exact term. But this all takes a few steps.
So, take a look at what our developers at Used-Line have done to make searching a cinch.
Used-Line has reduced the number of steps typically required to narrow down a search – to a single click. Here is how it works. We will use model 123 as an example.
- In the menu bar near the top of any page on Used-Line, start typing 123 in the text box that is prefilled with the words, Find Category or Model#.
- Wait for a second or less to view a drop-down list of all the models on Used-Line that contain the number 123, such as SEM123D, 1123A, 212359, and 011-0123-00.
- Select model number 123 from the list.
What we have actually done here is to select a specific model. When we previously searched for a 123 and simply waited for the results to come in, the system returned the 300+ models on Used-Line that contain the number, 123. Now, after picking the specific model number, 123, from a selection of suggested model numbers, the system returned 20 models – all exactly what we were searching for. Not only has our search been narrowed down – it has zoomed right into what we were looking for.
No more clicking back and forth between pages and pages of irrelevant search results.
Now you give it a try!
The Digital Multimeter (DMM) is the most fundamental test and measurement instrument in the electronic technician kit or engineer’s lab bench. It provides a number of functions, the most common being resistance, voltage and current. Secondary functions can include temperature, induced current, low frequency measurement, and other routine tests needed to troubleshoot circuits.
Many technicians use more than one digital multimeter, as they tend to be designed to suit a particular purpose in various environments. A DMM used in a clean room or laboratory is totally unsuitable for use in an outdoor environment or under harsh or hazardous conditions. In practical use, the DMM may need to be operated while wearing gloves during an ice storm, or may need to be handheld, extremely compact, and lightweight for portability. They can be rack mounted in a semi-permanent installation to be in close proximity to equipment that needs to be constantly monitored.
Here is an example of a DMM that can operate in temperatures below -40°C: The Agilent U1273AX.
DMM accuracy standards
Some DMMs are functional and practical, even without routine regular calibration certification. When the tolerance of a resistor may be 10% or 20%, a DMM accurate within 3% is generally sufficient. In the days of analog D’Arsonval meters, parallax distortion and the vagaries of electromechanical movement could result in erroneous readings near 2 to 3%. DMMS are far more stable and immune to misinterpretation of the readout.
DMMs have a relatively high attrition rate. This is the result of multiple meters required by each technician in the field and not so much a failure of an instrument. DMMs are designed to be used hundreds of times a day, both in laboratory and field conditions. Field equipment is often subject to abuse from impact of a dropped instrument to total immersion in water and similar environmental hazards. Laboratory equipment needs to be replaced as technologies advance and evolve.
DMMs are basically the same instrument, regardless of the make or model. What distinguishes one from another are cosmetic appearance and the user interactive interfaces. Each of these differences are highlighted as features. Not every meter can have every feature; it is up to the technician to know which configuration on a DMM is optimal for any given situation.
DMM advanced or enhanced features
Some typical enhancements include dual displays, RS-232, USB or IEEE computer interfaces, audible alarms or tone feedback, which enables the technician to keep his eyes on the device under test rather than on the meter. High-priced options include very tight measurement tolerances. Some enhancements can include backlit LCD displays, as opposed to LED displays. Induced current “clamp meters” and similar exterior measurement accessories are usually optional, but may be included as a part of a package. Some features include hold and store min/max readings, auto-ranging or auto-sensing circuitry and similar hands-free operation. If multiple and various readings are necessary, these features can offer a vast improvement over manual ranging and repeated button-pushing to change DMM settings.
Here is a DMM with a USB host port on the front panel: The Tektronix DMM4040.
Advantages of used DMMs
Of course, this is where Used-Line comes into the story. Leasing companies, larger companies employing scores of technicians, or smaller small- to medium-sized businesses seeking to stay within tight budgets can be well-served by considering procurement of used and re-certified, discontinued models or factory-refurbished DMMs. This is a cost-effective solution that will serve the company now and into the future. All technicians have particular makes and models of test instruments that they have high-confidence with using every day. In field applications, many techs prefer Fluke and Simpson meters for their ruggedness, durability and useful features without resorting to gimmicks or unnecessary bells-and-whistles. Given that some DMMs can cost over $10,000, depending on the degree of precision and accuracy required, buying used or as-new discontinued instruments can make or break a budget.
Selecting the right DMM
Choose the best quality instrument that meets your need. With higher-priced test equipment it is a wise idea to lease an instrument to ensure its suitability to the task. Realize that equipment turn-over for many of the top leasing companies is due to deprecating features or advancing technology. Leasing companies frequently sell their equipment to used-line.com clients in sufficient quantities to make offering them at steep discounts possible, with no sacrifice to name-brand quality, dependability and service.
We can’t exit this blog post without showing a Fluke. If you’re looking for 365-day stability, have a look at the Fluke 8508A reference multimeter.
The new Tektronix handheld spectrum analyzers, the H500 and the SA2500, which were recently added to Used-Line.com’s T&M Specifications page, are ruggedized instruments with an interface that has been designed for high quality visibility and easy navigation in the field.
But these usability features do not detract from the analyzer’s performance specifications. With a 10 kHz to 6.2 GHz frequency range, a +20 dBm to -160 dBm reference level range, and 100% POI for transients with 125 µs minimum signal durations (H500), these spectrum analyzers pack a punch that can be found in many desktop analyzers.
However, according to Jim McGillivary, general manager of the Tektronix Source Analyzer Product Line, “…what makes these instruments truly revolutionary is our unique real-time DPX™ live RF spectrum display technology. No other instrument or technology offers such a practical, fast and easy way to discover unknown, randomly occurring digital RF events.”