Military Hickok Tube Testers

Note: for UMB-118, see the Card-O-Matic listings

The tube testers that Hickok designed for the military were to military specifications. Further, once the tester was designed, it was then let to several companies to bid on production. For exmple, of the five TV-7 varients, only the "B" model was built by Hickok. In many cases the military model spawned a commercial one such as the 546 and the TV-3, however a few such as the TV-2 were unique to the military.

In a few cases commercial units with minor modifications were sold to the military (510X/OZ, 560/I-171, 123AF) but this was rare.

The following are presented in approximatly chronological order though there is some overlap.

I-177(A) The first model designed by Hickok specifically for the military during WWII was the I-177. This has the patented Hickok mutual conductance circuit and was based on the model 510 but was completley repackaged for field use.

Shown is a I-177B which is easily identified by the sockets for minature tubes above the meter face. Earlier models required an adapter to test minature tubes.

1945 Hickok I-177B

The first post-war tester to appear was the Navy TV-3(A|B). Pictured is a 1952 TV-3B. This tester was the basis for the later TV-10 and the simularities are easily discernable.

The most significant element of the TV-3(A|B)/U is that its operations manual, NAVSHIPS 91747 dated 5 September, 1952 has compete in one manual everything anyone would ever need to know about the TV-3. It is an operators manual, maintenance manual, parts manual, schematics, and even contains a complete printout of the roll chart data.

Note that the original TV-3 was considerably different in appearance though the general layout is the same and the early "window" selectors have given way to the silkscreened settings.

1949 Hickok TV-3       1952 Hickok TV-3B

With very little change and the addition of some new settings, the TV-3 was superceeded by the TV-10(A|B|C|D) - the original and A revision were produced by Hickok.


Oddly enough, the TV-2 was introduced later than the TV-3 though the original design may have been developed earlier. Intended as a replacement for the Weston OD as a depot-level tester, the TV-2 is probably the most complex tester ever to be called "portable". With six meters and settings for just about everything imaginable, there was little that the 700 could do that the TV-2 cannot. Apparently designed by the Air King company and not Hickok itself, the TV-2 rstill relied on the Hickok patents. If there is a limitation to the TV-2 it is the number of adjustments that must be made to test each tube and the fact that the shared power supplies meant that a specific order had to be followed in the setup.

Note that the complexity of the front panel required moving the roll chart to the lid along with the pin straighteners.


Probably the most popular of the military tube testers (and the most prolific) are the TV-7 series. Designed by Hickok, only the B model was produced by them however the extended range D model is the most popular.

It would appear that Supreme made the original series (TV-7/U) while the TV-7B/U was made by Hickok, the C model by Stark in Canada, and most D's by Forway Industries (Note: the foregoing is conjecture from a very limited sampling).

Except for the D model, on the surface there is very little difference between the units however there is considerable differences in the circuits. Attempting to repair a TV-7/U with a TV-7D/U scematic is an exercise in futility and missing potentiometers.

Repair and even calibration should always be made with the proper documentation. It is also important to know that there is a bewildering array of Technical Manuals (TM-) for the TV-7. These are:
TM 11-6625-274-12/1 Test Data for Electron Tube Test Sets
TM 11-6625-274-12 Operator's and Organizational Maintenance Manual
TM 11-6625-274-35 Test Sets, Electron Tube TV-7/U, TV-7A/U, TV-7B/U, TV-7D/U

NOTE: -12/1 contains the tube setting data and is carried in the top cover of the TV-7(all). -12 is an operators manual and contains no schematics. The schematics and calibration information for all models is found in the -35. The -35 (30 June, 1960) is also a replacement for TM 11-5083 (29 September, 1953) which had supplemental change notices (C1 -2 September, 1955; C2 - 8 February, 1956; C3 - 1 April, 1959; and C4 - 26 August, 1959).

TV-7s are popular because they are compact, relatively lightweight (though the large transformer in one end makes the unit somewhat unbalanced), and can test all older and modern tubes with the exception of compactrons.

The only drwback to the TV-7 is the fact that reading is in percent quality (0-120 scale) rather than GMhos so translation is necessary to compare to manufacturer's Gm values.