Measure transconductance/gm and match plate current with high precision. An opportunity to verify what you buy or sell, or keep tabs on your tube and amplifier investment with total confidence and no guessing. We warrant the tester for 12 months parts and 6 months labor, provided tubes are tested in accordance with the manual instructions. This rebuild and calibration is good for approximately 5,000 hours of actual in-service testing use before any 'check-up' should even be considered, that is about ten years for most users. Testing is done in class 1A conditions as per tube manufacturers data references.
This is a very easy to operate machine, you set the dials according to the numbers on the roll chart, verify the meter setting and after the tube warms, and take your gm and (if desired) plate current readings. If testing is new to you, we offer on line or telephone support to get you going, although the manual is very clear on setup and testing. After the fact help is always available.
This TRIPLETT MODEL 3444 LABORATORY TUBE ANALYZER has been completely rebuilt and calibrated to the original 18 page factory standards calibration document. To the best of our knowledge, no other service has these documents. The tester is burn-in for over 48 hours and retested to re-verify calibration to 1% or less (Triplett allows 3%). The highest and finest grade components were used including Sprague ATOM capacitors, Vishay military grade resistors, and new old stock tubes. We measure actual component values before use.
The condition of this 50 year old machine is remarkable and perhaps the best we have seen in many years, we invite you to examine the photos, please note the case does have some small but normal wear and tear marks which have been touched up by a local artist. The meter and deck face is near perfect, a few minor edge blemishes on the upper far right and left. It was owned by the US ARMY originally, their certification sticker can be seen on the roll chart frame.
The tester Includes a copy of the manual and supplemental tube data thru 1972. The manual tells the proceedure to create new tube settings if desired. Please see the note at the bottom of this description for options.
Technical specifications for the Triplett Model 3444
Gm SIGNAL POTENTIALS AND RANGES
Four direct reading Gm ranges
Four signal potentials @ 5 kHz
Filtered DC, 85 volts. In accordance with EIA G-8 Committee recommendations.
0 to 10 megaohms at 85 volts (measurements made directly on the meter).
PLATE POTENTIALS AND CURRENT RANGES
Four filtered DC plate potentials.
Two DC plate current ranges Match tubes professionally by milliamp.
5 ma full scale
50 ma full scale
* please see option at bottom for upgrade to 10 and 100ma measurements (modified Triplett 3444-A circuit)
Two filtered DC bias ranges (on 50 division dial so that actual bias voltages can be read
0 to 5 volts
0 to 50 volts
Five filtered DC screen potentials
Twenty-three AC voltages closely regulated:
Gm CIRCUIT CHECK
Self checking GM circuit with 5 kHz signal source and vacuum tube micrometer.
Grid current test under operating conditions.
Cut-off measurement on voltage amplifiers.
Test for rectifiers is made under load.
DUAL PURPOSE TUBES
Single element switching set up for dual purpose tubes, such as 12ax7.
Firing voltage grid current and cut-off measurements in thyratrons.
Output 1.5 volts, 5000hz.
Rugged 200 micrometer, illuminated, with 4" scale length and knife edge pointer.
Noise test jacks for checking noisy or intermittent tubes.
Roll chart illuminated and removable.
Combination 4-5-6 prong; combination 7 prong; octal; loctal; 7 pin subminiature; 8 pin subminiature (round); 7 pin miniature; 9 pin miniature; nuvister on serial number above 3,000; acorn adapter (supplied with analyzer - stored in roll chart compartment). Octal, 7 pin miniature, 9 pin miniature are socket-savers for easy replacement from the panel. NOTE--The red dot on the panel next to the 7 pin subminiature socket indicates pin No. 1. This usually is indicated on the subminiature tube with a red dot.
PIN STRAIGHTENER DIES
7 pin and 9 pin straightener dies on panel.
Wood, gray leatherette covered
Red bulb lights with excessive overload.
3 amp, 250 volt, type 3AG in roll chart compartment.
Power 117 to 124 VAC
Option: expansion of the milliamp meter to read 100ma for tubes such as 2A3 which exceed 50ma. This requires removal of the 7 pin straightner where a switch is added giving a 1X and 2X ( or 3 X ) factor to the milliamp meter. Or, the change can be made permanently (no switch) so current is 10 and 100ma. This scale expansion allow matching of higher power tubes auch as a 2A3. The switch option is $55.00 and takes a few days to install and calibrate, it will delay shipping. The permanent change is 25.00. If you need up to 200ma reading ability, please inquire.
We have been in business since 1973. 1100+ positive feedbacks on eBay. We refurbish and restore vacuum tube testers, modern and vintage tube equipment, hot-rod and custom reworks included. You are invited to contact Joe at Tempo Electric an Audiogon member as a reference who had his 3444 fixed by us in one week after a California company had it for two years and returned it to him still broken. Please check our Audiogon feedback as well.
Buyer pays shipping and we require sign for and full insurance.
Why is this tester considered better than the Hickok 539 series ( or Western Electric)? Answer: because all Hickok testers (including TV series) use two tube based rectifiers and unless the pulsed DC from each side of each tube are always equal ( impossible unless balancing circuits are installed which we do) the differences are shown on the gm meter as a plus or minus of actual gm tube value. Only the Hickok 539C attempted to correct this problem BUT Hickok only corrected half the problem on just one tube. The Triplett 3444 has no issues like this. Hickok also used a 60hz power-line signal, the Triplett uses a 5000 hz generated signal. Many Hickoks' can damage frame grid tubes, the 3444 can not. There is good reason why industry, the military and government agencies such as the FAA turned to the Triplett 3444 in the 1960's and thereafter. This is likely the finest vacuum tube tester ever made.