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Tube Tester TV-7 U

Tube Tester TV-7 U; MILITARY U.S. (ID = 255274) Equipment
Tube Tester TV-7 U; MILITARY U.S. (ID = 255278) Equipment
Tube Tester TV-7 U; MILITARY U.S. (ID = 255279) Equipment
Tube Tester TV-7 U; MILITARY U.S. (ID = 55642) Equipment Tube Tester TV-7 U; MILITARY U.S. (ID = 209491) Equipment
Tube Tester TV-7 U; MILITARY U.S. (ID = 315937) Equipment Tube Tester TV-7 U; MILITARY U.S. (ID = 619122) Equipment
Tube Tester TV-7 U; MILITARY U.S. (ID = 619123) Equipment Tube Tester TV-7 U; MILITARY U.S. (ID = 619124) Equipment
Tube Tester TV-7 U; MILITARY U.S. (ID = 746722) Equipment Tube Tester TV-7 U; MILITARY U.S. (ID = 825706) Equipment
Tube Tester TV-7 U; MILITARY U.S. (ID = 825707) Equipment Tube Tester TV-7 U; MILITARY U.S. (ID = 825708) Equipment
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Tube Tester TV-7 U; MILITARY U.S. (ID = 55642) Equipment
MILITARY U.S.: Tube Tester TV-7 U [Equipment] ID = 55642 541x498
Select picture or schematic to display from thumbnails on the right and click for download.
For model Tube Tester TV-7 U, MILITARY U.S. (different makers for same model)
Country:  United States of America (USA)
Manufacturer / Brand:  MILITARY U.S. (different makers for same model)
Year: 1953 ? Category: Service- or Lab Equipment
Valves / Tubes 2: 83 5Y3GT
Wave bands - without
Power type and voltage Alternating Current supply (AC) / 105-125 Volt
Power out
from Model: Tube Tester TV-7 U - MILITARY U.S. different makers
Material Metal case
Shape Tablemodel, with any shape - general.
Dimensions (WHD) 440 x 220 x 155 mm / 17.3 x 8.7 x 6.1 inch

Tube Tester TV-7 /U.
This model /U was built by Supreme.
This model was also produced for NATO by Lorenz, Germany.

External source of data Ralf Sürtenich
Literature/Schematics (4) -- Schematic

Model page created by Ralf Sürtenich. See "Data change" for further contributors.

All listed radios etc. from MILITARY U.S. (different makers for same model)
Here you find 348 models, 302 with images and 170 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.


Forum contributions about this model
MILITARY U.S.: Tube Tester TV-7 U
Threads: 2 | Posts: 7
Hits: 1743     Replies: 1
military: TV-7 U; Fuse bulb & pilot lamp
Olivier Palix

I have a TV7/U,it use a bulb as a fuse.It is important to use the correct type: 81,(6,5V,1,02A;6,6W).

I have found that types 81 & 47 (pilot lamp) bulbs are used in Gottlieb flippers, so it is easy to buy them at sellers  of flippers spares parts  (in France there is one on,he sell box of 10  at very reasonnable price)

On the picture,the; yellow bulb is original (GE81),he silver one is a 81 for flipper (exactly similar to original).

I have tested the spares,they runs as originals ones.Using european cars 6V bulbs is also a solution,but they do not complies exactly (6V; 5W ),flippers spares are preferables.

Olivier Palix


Michael Watterson

Actually 6V car bulbs are really 7V and 12V car bulbs are really 14V. This is because the 12V car battery is over 14V on charge and traditionally was a nominal 13.8V. Car bulbs (lamps) also must give reasonable life. In contrast a 6V dry battery lamp may have a 4.8V lamp and be rated only 500 hours or much less (so as to be more efficient). The almost orange shade pilot bulbs are longest life and thus lowest efficiency, some may be 5,000 hours. As a rule of thumb, increase of 10% Volts is 1/2 life, or a 10% decrease might double life, very white filaments are short life and more orange filaments are long life.

The 6.3V of indirect valve filaments is derived from 6V lead Acid battery applications in 1930s, including early car radio sets. Modern low maintenance or "calcium" technology 12V batteries are closer to a nominal 14.2V than 13.8V when charged but on load (i.e. in a car with engine running).


Hits: 18389     Replies: 4
military: Gm reading on TV-7 tube testers
Emilio Ciardiello

TV-7 military tube testers are appreciated and widely used because of their versatility, ruggedness and simple operation. Unfortunately the meter just gives arbitrary values, from 0 to 120, and data tables indicate the minimum acceptable value for each tube.

But the arbitrary values of the meter can be easily converted to the actual mutual conductance Gm, expressed in micromhos, using the table below.


Intermediate values can be readily calculated by linear interpolation.

The table comes from the TM 11-6625-274-12 manual, covering models TV-7/U, TV-7/AU, TV-7/BU and TV-7/DU. Probably it should also apply to TV-7/CU.

Kurt Schmid

Beside the arbitrary values of the scale of the meter of the TV-7, BIAS control setting also uses arbitary values (0 to 100). However, the average user is interested in explicit grid voltages. I have compiled a chart that converts the arbitrary readings of the BIAS potentiometer to real world grid bias voltage.

But keep in mind that the above DC-BIAS voltage in addition is superimposed by an AC grid signal of variable amplitude. This serves to perform AC modulation (with line frequency) of  plate current and measurement of mutual conductance (= transconductance, Gm).

BTW, the amplitude of the AC grid signal is changed with the the range selector (B-F). Signal is lowest in RANGE F (highest transconductance).

The following table is an upgrade of the table contained in technical manual TM11-6625-274-12 as shown in the posting of Emilio and also covers the TV-7D/U. The TV-7D/U has an additional measuring range 'F' allowing the measurement of Gm up to 60.000 micromhos (=60 mA/V).



Stefano Sbravati

Thank you for this important contribution. 

My question is: what is the "minimum value" standing for in terms of percentage of Gm? 

Second question: usually valve manufacturers indicate different Gm's according to different settings (Vg, Ia, etc...). What is the setting to be used to compare Gm reading on the TV-7 meters with Gm declared by the manufacturers? 

Many thanks again

Emilio Ciardiello

The column 'Minimum Value' just gives the minimum reading expected for an acceptable tube on an arbitrary scale. Tubes returning readings under these values should be replaced. It can be compared to the separation line between 'Replace' and 'Good' available on other tube testers.

Referring to the second question, the TV-7(*) is a tube tester, not a tube analyzer. It checks the Gm in a Hickok simplified circuit, where the tube is connected as a triode, regardless of how many grids it has. To perform the measurement you are asking for, you should have on hand a tube analyzer, like this TV-2.


Alan Scott Douglas † 16.11.15

Only one model of Hickok tests all tubes as triodes, the 799.  Others apply screen voltage, typically 130V, while the plate is at 150V.

MILITARY U.S.: Tube Tester TV-7 U
End of forum contributions about this model