What does the AT1000 Tube Tester do?
The AT1000 will automatically test diode, triode, tetrode, pentode and heptode vacuum tubes
for shorts, emission, mutual conductance (GM), and gas and heater-to-cathode leakage (where
applicable). It tests both single and multiple-section tubes. It also tests Electron Ray
Indicators (“Magic Eye" Tubes). A headphone jack is provided, to enable the user to listen
for microphonics in any amplifying tube, including power tubes.
What tubes will the AT1000 test?
The AT1000 accommodates 7 and 9-pin miniature tubes, standard octal tubes, and 4, 5 and 6-
pin small-base tubes with a heter or filament voltage between 1.0 and 12.6 volts. Direct
(filament) or indirect-heated (heater/cathode) tubes can be tested. Tubes with a grid or
plate cap can also be tested.
Many large power tubes, such as the 6C33C and 211 and 845 can be tested with optional
adapters.
How is the AT1000 different from other testers?
The AT1000 was designed with audiophile and musical instrument tube testing in mind. Unlike
many vintage testers that have only 165 to 250 VDC available for testing, the AT1000 can
operate tubes at up to 500V and 160 mA - the power levels output tubes see in real-life
equipment.
Many vintage testers were designed for television and radio tube testing. Some do not even
test transconductance, or GM, they only measure simple cathode emission.
Some vintage testers give you the results in arbitrary, meaningless, units. The AT1000
shows your emission results in DC milliamperes, and transconductance in mA/V (1 mA/V = 1000
uMHOs). In most cases, the test settings and expected results are taken directly from
vintage tube data books.
Vintage testers have mechanical analog meters that stick with scales that are hard to read.
The AT1000 has a backlighted LCD display, that shows you the test results after all tests
have completed. You can view these results indefinately, until you switch off the power, or
test another tube. The display shows you not only actual tube performance in engineering
units (DC mA, Volts, mA/V, etc.), but also gives you a "percentage of specification"
reading. Both Emission and Transconductance results have the percentage feature. It's a
quick and simple way to evaluate how your tubes are performing compared with actual,
published manufacturer specifications.
Other current-production tube testers and tube matchers are now available. Some can test at
up to 400V. But none perform such complete testing as the AT1000, or are as simple to use.
The AT1000 will test preamp AND power tubes - not just one kind. There are no analog
adjustments to make, no socket modules to rewire, and no measurements to make with external
equipment. The AT1000 sets up the tube pinout, tells you which socket to use, adjusts the
power supplies, times the warmup and makes the measurements. You just sit back and watch!
What about matching tubes, can the AT1000 do this?
Absolutely! Not only will it match tubes by plate current (emission), but tubes can further
be matched by transconductance. Matching of multi-section tubes is possible too, since the
results for each section of such a tube are displayed separately. And most importantly, it
will match tubes at normal current and voltage levels, faithfully reproducing the actual
operating conditions found in many amplifiers, preamps and other equipment.
How about roll charts, lookup tables, etc?
These don’t exist with the AT1000. The tester’s internal FLASH memory contains test data on
over 400 types of the most popular tubes, including vintage and high-end audio power and
preamp types, European types, mil-spec/industrial, and some transmitting types. By
connecting a personal computer, it is possible for the user to change, add, or delete tube
test setup data.
How long does it take to test a tube?
The time can vary, from as little as 40 seconds to about three minutes. It all depends on
the voltage and current values being applied during the test, and how many different
sections a given tube contains, whether Auto or Fixed Bias is selected, and a few other
parameters.
What tests does it perform on Electron Ray Indicator types?
The AT1000 is capable of testing tubes such as the 6E5, 6BR5/EM80, 6HU6 and more. The
display section of such tubes is tested using the nominal operating voltages, and allows
the user to check for brightness and shadow movement. If the tube has a separate triode
amplifier section, it is tested for leakage, emission, shorts, transconductance and gas
just like other triodes.
Tubes operate at high voltages, is the AT1000 safe to use?
When the directions, cautions and warnings in the manual are followed, the AT1000 is
perfectly safe to use. It should not be used by persons unfamilliar with the hazards of
high voltage and hot tubes. It should not be used by persons under the age of 18 without
the close supervision of a knowledgeable and responsible adult.
What special design features does the tube tester employ?
The AT1000 contains independently-adjustable Plate, Screen-grid, Control-grid and Heater
Power Supplies. Each power supply is fully regulated to within better than 1% of its full-
scale voltage, and is protected against overloads and short circuits. No pre-regulator or
stablizing transformer is needed, nor is recommended. Line voltage sag, drift and noise has
no effect on the test results.
The Plate/Screen and Heater supplies are each ramped-up over a brief interval, avoiding
thermal shock to your valuable tubes. The power supplies are also protected against
overheating by thermal protective devices. Should the unit overheat, the user is notified
to wait until it cools down, and further tests are inhibited until this occurs. Internal
fuses protect the unit in case of catastrophic circuit failure.
The Amplitrex AT1000 Tube Tester FAQ
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