It is a small, simple tester in an excellent condition. There is just one switch to choose the filament voltage, that's all.

It has a  lot of sockets:

• Aussenkontakt 5-Pin (also for UX-5 !!!)
• Aussenkontakt 8-Pin
• Octal
• Europe 4-Pin/5-Pin
• Hexode 7-Pin
• UX4
• UX6
• UX7
• American small 7-Pin

Being a design of 1936 the Vollnetz 36A has no socket for German StahIroehre. So I've build an adapter to test tubes with Stahlroehre-base. I've used the base connections of an EL11 pentode (Stahlroehre) and matched it with the base connections of an EL3 pentode (Aussenkontakt 8-Pin), which means 2 x heater, 1 x anode/cathode and 3 x grid. The base of an old Aussenkontakt-tube holds now a regular Stahlroehre-socket.

A second adapter with a Stahlroehre plug contains Reichspost sockets 5-pin and 7-pin and an additional Rimlock-socket. This adapter was build by Volker Jeschkeit.

The I-177 B is an US-Army tube tester, it measures dynamic transconductance. It is using 2 tube rectifiers: a 83 for anode voltage and a 5Y3GT for grid voltage.

Being an US-Army tester it has only American tube sockets:

• UX4
• UX5
• UX6
• UX7
• Octal
• Loctal
• Pico 7-Pin
• Acorn (US-Army)
• Bantam 5-Pin

The I-177 tester was along with his civil brothers the last Hickok design with a fixed circuit switching for tube testing. The later designs allow to control each grid of a tube individually, which makes it easy to test also tubes not mentioned in the manuals. To overcome this issue there was an expansion box for the I-177, called MX-949. This box has leads for each socket contact to be connected on the fly which gives the freedom to switch virtually for every existing tube basing.

This is the schematic for the I-177:         I-177 in gif-format

And for the MX-949 expansion box:      MX-949 in gif-format

I've found an excellent page about US-Army testers made by Nolan Lee:

Nolan's Redneck Boatanchor Page

Nolan is doing a great job compiling tube settings tables for some of this testers, mainly the I-177 and the TV-n models.
 
My 2nd I-177, a first series model, I got without the meter. Nolan told me spare meters are availabe at Fairradio Sales (see my audio mainpage), so I got one and started to rebuild the beast. In Germany I was not able to find the glow lamp for it. I changed the socket to an European E-10 socket and can now use 115V glow lamps available in Germany. Another problem were the screws because they also have no ISO sizes. Thanks to George Rigney in California I got a lot of inch-sized screws to solve this problem. I changed also a cap in the tester, and then it runs the tests pretty well. At last I decided to give it to friend, now it is used by Uwe Menrath in Tauberbischofsheim ;-)

Later I also sold the I-177 B tester to Hong Kong.

• UX4
• UX5
• UX6
• UX7
• Octal
• Loctal
• Pico 7-Pin
• Noval 9-Pin
• Acorn (US-Army)
• 2 types of submin sockets

Originally there was a plate with 4 additional sockets mounted in the lid, the Stark ED adapter, but unfortunately removed. It was equiped with british tube sockets, due to the reason the TV-7 C/U model was build for the Canadian Armed Forces.

This is a picture of a full equiped TV-7 C/U lid with Stark ED adapter. Actually I've sorted out which sockets are mounted in it  (left to right):

• B9G (e.g. for EF50)
• Mazda Octal (UK Octal)
• Europe 4-Pin/5-Pin
• B7 UK (e.g. for MDH4)

I'm trying to get this sockets and rebuild the plate in my tester.

With the help of my friend Yoshitaka Shibuya I was able to draw a wiring diagram of the Stark ED adapter (.gif):

Stark_ED adapter

Any information about Stark ED adapter test data is very welcome !!!

The great advantage of the TV-7 is: the tube test data were updated until 1972. So with the TV-7 you have the choice to test most tubes in the world (beside of some old European pre-WW II tubes), it is highly flexible and has a really huge tube data list. Nolan Lee is doing the job to compile al the available test data in a really huge Excel-Sheet: Nolan Lee's TV-7 Index

The test data manual TB 11-6625-274-12/1 you can find here:  TV-7 Test Data

One problem firing up the TV-7 was a 1st issue: the line adjustment feature didn't worked. But I was prepared for that, got the 

TM 11-6625-274-35 field and depot maintenance manual (availabe at  TV-7 Field and Depot Maintenance

and was able to figure out a diode bridge was gone. I took two 1N4007 and it was fixed. Checked both rectifier tubes, a 83 and a 5Y3GT like in the I-177 tester, and the TV-7 was ready to run.

Then I thought a calibration was needed. When I'm testing rectifier and stabilizer tubes the results are acceptable, but testing triodes the tester shows very less power. My really best and strongest tubes type triode #27 are just ok according to the test result, all others are bad. This was a real difference to my #76 triodes. Beside of the filament voltage and current this tubes are really close. There was something to sort out! 

I did the calibration tests according to the maintenance manual, using a 50V AC source and and a 10k resistor. And surprise: calibration was within the tolerances. After some discussions I found the reason: when testing tubes with a higher filament current draw, the voltage goes down nevertheless the line adjustement is regulated. Connecting a voltmeter to the tube's prongs and adjusting to the right filament voltage gives much more reasonable results. So I thought about the repaired Line Adjust feature and did some tests. Yes, with an additional 50k resistor in the line adjust circuit it looks much better. I assume the original diode bridge had a higher voltage drop compared with the 1N4007, so the adjustement following the meter's indication was not right. A 50K resistor is a workaround which was allright.

But then I did things better. I got 2 Selen single-wave rectifiers made by AEG, specified for 400V and 20 mA. And now it looks right, function of the line adjust circuit is reliable without an additional resistor:

Doing this job I've learned the TV-7 C/U is internally exactly like the 1st series TV-7 /U, which was build by Supreme.

This is the schematic of the TV-7 C/U (/U) in .gif-format: TV-7 /U (190k)

Thanks to Volker I got data about tube equivalents (European codes vs. American codes) from the Allied Forces Italy used with tube testers. I compiled it in an Excel-File: European_Tubecodes

And over a time of 2 years Dieter Waechter did a fabulous job to build a huge crosslist about American and European tubes: 

Dieter Waechters Crosslist (.zip file of 191k)

The Elettra Oscillatore Modulato mod. 412 is a RF generator, build by Scuola Radio Elettra in Torino/Italy. It covers 4 bands:

The mod. 412 uses 1 tube, an ECF80.