Please click your language flag. Bitte Sprachflagge klicken.

Tube Tester I-177

Tube Tester I-177; MILITARY U.S. (ID = 382250) Equipment
Tube Tester I-177; MILITARY U.S. (ID = 2376775) Equipment Tube Tester I-177; MILITARY U.S. (ID = 2376776) Equipment
Tube Tester I-177; MILITARY U.S. (ID = 2376777) Equipment Tube Tester I-177; MILITARY U.S. (ID = 2376778) Equipment
Tube Tester I-177; MILITARY U.S. (ID = 2376779) Equipment Tube Tester I-177; MILITARY U.S. (ID = 2376780) Equipment
Tube Tester I-177; MILITARY U.S. (ID = 2376781) Equipment Tube Tester I-177; MILITARY U.S. (ID = 2376782) Equipment
Tube Tester I-177; MILITARY U.S. (ID = 2376783) Equipment Tube Tester I-177; MILITARY U.S. (ID = 391882) Equipment
Use red slider bar for more.
Tube Tester I-177; MILITARY U.S. (ID = 2376775) Equipment
MILITARY U.S.: Tube Tester I-177 [Equipment] ID = 2376775 1024x768
Select picture or schematic to display from thumbnails on the right and click for download.
For model Tube Tester I-177, 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: 1944 Category: Service- or Lab Equipment
Valves / Tubes 2: 5Y3 83
Wave bands - without
Power type and voltage Alternating Current supply (AC) / 115 Volt
Loudspeaker - - No sound reproduction output.
Power out
from Model: Tube Tester I-177 - MILITARY U.S. different makers
Material Metal case
Shape Tablemodel, with any shape - general.
Dimensions (WHD) 5.7 x 15.5 x 8.5 inch / 145 x 394 x 216 mm
Notes This was the mutual conductance tube tester used by US Armed Forces since WWII.
Net weight (2.2 lb = 1 kg) 8 kg / 17 lb 9.9 oz (17.621 lb)
Source of data - - Manufacturers Literature
Documents regarding this model
  Aggiornate il vostro Hickok I-177 2162 KB

Model page created by Emilio Ciardiello. See "Data change" for further contributors.

All listed radios etc. from MILITARY U.S. (different makers for same model)
Here you find 352 models, 304 with images and 168 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.


Forum contributions about this model
MILITARY U.S.: Tube Tester I-177
Threads: 1 | Posts: 10
Hits: 8436     Replies: 9
How to test tubes not listed on Hickok I-177?
Marco Gilardetti


I have recently purchased a Hickok I-177 tube tester with its expansion box. As the expansion box needed an intense recabling, I am now undergoing the process of adding other European-type sockets not originally present on the board while I’m on the task.
My concern is of course the fact that most European tubes are not listed in the data sheets. I see that a lot of work on this matter has been done by Nolan Lee (that’s why I was willing to <a href="">get in contact with him</a>) and other fellows here and there on the net, but many tubes are not yet covered. Just to name one type: tubes with side-contact base.
Since the set up of the ammeter on the I-177 is very easy (one potentiometer only, the other one is fixed once the scale is set to MicroMhos) I was wondering if some of you fellows developed a general method to test tubes when the tube chart is given. Tube charts are easy to find on internet, so they’re no longer a problem.
What about comparing set-up values with the TV-7 model, which seem to have more literature? Is there some kind of conversion procedure to set the I-177 once the setup for the TV-7 is given?
Any comment on this subject is welcome.
Emilio Ciardiello

Dear Marco,

it is not so easy to use I-177, and its MX-949 adapter, to test tubes not listed in their data tables. I-177 circuit is very simple and does not allow the setting of the operating parameters as specified in the manufacturer’s data books. There is just a single anode and no screen grid voltage supply. The sole parameter you can change is the control grid negative bias. The settings given in the tables for L and R potentiometers refer to a triode connected test circuit, with fixed drive and fixed supply. There is no direct relation among the couple of values for R and L, grid bias and meter sensitivity, and the effective grid bias and Gm given in the tube data books. You have to find new settings for any tube not listed in the tables and in their updating pages, using some elsewhere calibrated references.

TV-7 is similar to I-177 and has the same limits. Even if it can measure a lot of miniature and new tubes, I never saw a setting table for old European tubes, as side-contacts or German metal ones.

The I-177 is my preferred meter to perform quick checks of U.S. tubes. It may be easily adapted for checking European tubes electrically similar to the types listed, only differing in the envelope or in the socket. For other European tubes, a European tester could be the easier solution.

Regards, Emilio

Marco Gilardetti

Hello Emilio, first of all thank you for your very informative answer, I really appreciate it. I think you already guessed that I don't have money to buy nor room enough to store another tube tester, not even to mention the annoyance of going through dozens of them to find one (supposedly) properly working.

On the other hand, I'm not looking for the full accuracy or speed the I-177 can give. In most cases one only need to know if the tube is completely shot or works somehow. In other words, for example, I'm not expecting to get the handy "good / replace" reading for which Hickoks are famous: as far as I'm concerned the L potentiometer can be left on "Gm" position so that the answer may be read directly in MicroMhos. And as long as the datasheets are now easily available, one always knows how many MicroMhos the tube under test is supposed to show. By doing so, the potentiometer R seems to be (correct me if I'm wrong) the only thing which actually needs to be set up, all the rest (wiring, etc.) being given by datasheets.

So now the question sounds like: may the setting of potentiometer R be known once one has the datasheet? Or can the R potentiometer be set empirically through measurements (voltmeter or oscilloscope) performed directly on the tube socket under use?

Finally, what about deducting the setting of R by comparison with other tube testers for which the data are widely available even for european tubes? Like our SRE emission tube tester, which reports data for european and US tubes as well?

Emilio Ciardiello

Dear Marco,

may be I was not able to properly transfer my thought: absolutely no idea to blame or judge your decisions. Nor I want to annoy anyone with considerations about the many models available: everyone uses the model he gets at the best of its capabilities. I tried just to explain how difficult may be to find a new couple of R and L values for each new tube. The tube data updating was the most complex and expensive after-sale task of any tube tester manufacturer.

The values given in the data tables of the tube tester to set both R and L potentiometers cannot be directly derived from the data given in the datasheet, which are referred to the typical circuit, with certain anode, screen grid and other electrodes supply values, well defined input signal amplitude and the nominal load.

In the I-177 you can only perform a measurement in the circuit given in fig. 6 of the operating manual, the result being then related to the Gm. Any tube under test is actually connected as a triode, with fixed plate voltage and fixed input signal voltage. You can only move the grid bias voltage, potentiometer R, to stay within the proper dynamic range and the safe operating conditions for the tube. As you can easily verify from the data tables coming with the set, the settings of the grid bias potentiometer are not proportional to the negative bias values given by the manufacturers for each tube. The difference is evident when you give a look to some tubes rated for relatively low B+ voltage, as those for battery operation. Just one example: the grid bias specified in GE Essential Characteristics for both the 1G6 or the 1L4 is 0V. But the I-177 tables give R setting values of 13 and 16 respectively. These operating points were probably chosen to limit the anode current to safe values and to prevent the grid going positive.

The use of data tables of different models is possible provided that models use the same circuits and the same voltages. I do not know if Hickok made export models with data for European tubes. Neither for the I-177, nor for the newer TV-7, I have ever seen any official supplement data concerning European old tubes. The TV-7 tables give test data for some CV and some recent European tubes.
It is possible that someone has put on the Web a couple of setting values for say the EL3, but how reliable are them? Here the reasons why I still prefer the quick and reliable I-177 whenever possible, but use different sets for European tubes, a Chinaglia or an Avo depending upon the case.

Regards, Emilio



Marco Gilardetti

Emilio, thanks for your detailed insight.

I see that the only path would be to undergo a cooperative work with owners of more than one tube tester and with samples of known-working tubes to deduct setting values.

However, it seems that no one else is interested in this subject except you and I, so it is more wise for me to forget it and skip to something else.

You've been very kind, thanks a lot again.

Keith Hardy

I am in need of a Hickok Model 531 (KS-13588-L1) operation manual.  Is there one online that can be downloaded?  The tester I possess seems to be in good working order.  Some of the labeling is missing on the facing as well. 

Thank You!

Keith Hardy


Ernst Erb

Dear Keith
You have a good chance to get technical papers if you use the link "Create New Model" on the search page and enter your instrument. After acceptance you can load up your picture and you can use the link for acquiring the technical information.

Keith Hardy

Hello Ernst,

Thank you for your response. I am new to this handy site and still learning my way around.



Ernst Erb

Dear Keith
You have done very well - but I had to correct small things. You can look at the process of accepting by clicking "Pending Models" under Community on the Search page. You then also see then it is up.

Dale Spear


I have been using the I-177 for many years and was interested in this thread. Years ago I converted my tester to test newer tubes by building an adapter into the lid. This was done from plans in QST.

I have used a tube chart designed for the Hickok 6000 dated 1971. This seems to work pretty well. Of course the adapter you are using should work using this chart also. The L and R settings in this chart are on a 0 to 100 scale instead of the 0 to 80 of the 177 so a new dial or some math calculations are necessary.

I am no authority on this but wanted you and Emilio to know that I am interested and would like to be informed of any new ideas you may have.

Also, there is a link which has some information on this. Just scroll down to the Hickok I-177.



MILITARY U.S.: Tube Tester I-177
End of forum contributions about this model