Hickok Model 3300 Digital V.O.M.
THE new Hickok Model 3300 looks like a real workhorse of a portable v.o.m. except that, instead of the usual meter scale, a digital display is used.
Measuring only 8-in high by 5 7 /8-in wide by 4-in deep and completely battery-operated if desired, the d.v.o.m. is easy to carry and convenient to use.
The meter has a 3 1/2-digit display; that is, there are three complete 0-9 digit decades while the fourth digit is either a "0" or "1." There are 27 measurement ranges including 5 a.c. and d.c. voltage ranges, 4 a.c. and d.c. current ranges, and 7 resistance ranges. A high-voltage range (15 kV) is also available using a separate h.v. probe.
The meter may be operated from a 115-or 230-volt a.c. power line or from its internal rechargeable nickel-cadmium battery pack. The batteries permit a full 24-hour operation so that the meter can be used at field locations for extended periods of time. The meter may be operated from a.c. power while the battery pack is being recharged.
The bright fluorescent digital display consists of 7-segment numerical indicators, which provide a maximum display of 1999. Display features include an automatic polarity indicator, automatically positioned decimal point, and an out-of-range indication. Overrange is indicated by a blanked display which occurs when the reading exceeds 1999.
The reading rate is one per second.
The test probes are permanently attached to the front panel and are fitted with a captive strap, which secures the probes to the combination carrying handle and tilt bail.
For operator protection on high-voltage measurements, the case is completely isolated from the input terminals and contains no metal on the outside. Only the probes selected by the switch settings are connected to internal circuitry and no damage to the instrument will result if the wrong probes are used or if the instrument has been incorrectly set up.
A high-impact-resistant plastic case, shock-mounted readout, and a wide temperature operating range make this a rugged instrument for field applications as well as for laboratory and production-line use. Price of the Model 3300 is $395, including battery pack and regular probes.
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B &K Model 607 Tube Tester
DESPITE all the transistorized TV sets and hi-fi receivers, there are still a good many pieces of equipment that employ vacuum tubes. Not only does this include some not-so-new TV sets, but there are quite a few hybrid sets coming out this year that use tubes along with transistors and IC's. In order to test these tubes, the technician needs a simple and quick-to-operate tester like the new B&K Model 607.
The tester has a couple of unique features that are worth noting. One of these is a novel short-circuit test that permits the user to lock out one tube element at a time from the grouping of elements that are tied together for the usual shorts test. In this way, the user can isolate where any internal short occurs and not overlook other internal shorts that may exist in the tube.
Another interesting feature is the series of shape-coded windows through which the setup readings are seen. By sliding the tube setup chart booklet up and down behind the flap in the cover of the tester, only one line of readings at a time can be seen. It is like a built-in roll chart but without the roll. By making the opening with different shapes (hexagon, triangle, square, rectangle, circle) and by matching these shapes with the control numbers, the setting up of a tube test is very fast and requires no searching and hardly any thought at all. It's just a matter of pushing in a button and reading the meter.
The tester checks just about all presently available tube types for cathode emission, grid leakage and emission, and shorts and leakage. Less than 1 microampere of grid current can be detected. The manufacturer refers to the tester as a solid-state unit; it does use an FET amplifier to drive the meter for grid checks and there are semiconductor diodes for power-supply rectification and regulation.
The tester is housed in an attractive, weatherproof, durable attaché-type carrying case. It sells for $114.95. Test data on new tubes is available every four months on a $5 per year subscription basis.
General Radio Model 1542 Stroboscope
AN electronic stroboscope, which produces bright flashes of light at a variable repetition rate, has a good many applications. It can be used in the industrial area to "freeze" machinery motion for inspection and design; it can be used in schools or labs to demonstrate the principles of physics; and it can be used in the home, in clubs, or even the concert hall as part of a psychedelic light display with color organs for recorded or live pop music.
The new General Radio Model 1542 provides bright white light flashes from a xenon lamp whose rep rate ca be varied from 180 to 3750 flashes per minute. There is constant image illumination at any flash rate, while the flash duration can be as short as 5 microseconds. The stroboscope uses a reflector that confines the light to a beam angle of 40 degrees.
The unit operates from the a.c. power line from which it draws only watts. The case is unbreakable molded plastic with a face plate to protect the flash lamp. A threaded hole in the case is for tripod mounting.
The 1542 is useful for observing the working of high-speed machinery. Set ting the flash rate to coincide with the machine motion provides a "stopped image while the equipment is working A slight change in the strobe flash rat shows the machine moving in slow-motion so that its operation can b watched. Devices operating at speed greater than the strobe flash rate ca be stroboscopically observed by setting the flash rate to a sub-multiple of machine speed.
The company makes other more elaborate and more expensive stroboscopes. The Model 1592 is its latest and lowest-priced unit. It is available for $95.
Also see: EW Lab Tested
Testing Hi-Fi Equipment--Part 2. Test Procedures , Julian D Hirsch