I had one of these back when I was about 15. I recall that just about every single wire had been cut and I spent many hours splicing it back together. I also out a NOS transformer in it I got from Fair Radio Sales. It did work fairly well, but I ended up selling it a couple years later at a ham fest.

Flash forward about 25 years and I find myself in need of a respectable tester for pre war tubes. So I got on eBay and spotted this guy that looked to be in very good condition. No pictures of it working or of the inside though. Here's all the seller had to say about it

HERE IS AN OLD ARMY AIR FORCE TUBE TESTING MACHINE IN WORKING ORDER AS FAR AS I CAN TELL. I PLUGGED IT IN AND HIT A BUTTON AND THE NEEDLE MOVED TO THE MIDDLE. IT'S HEAVY AND HAS THE ORIGINAL MANUAL STILL IN THE BOX. THANK YOU FOR LOOKING.

The price was reasonable so I picked it up.

Here she is. The control panel is in excellent shape. Looks like the paint may have been touched up a little.
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I carefully removed the screws and pulled the chassis. It's very, very clean inside. All that anti-fungal varnish probably help preserve it.
There's a schematic built into the bottom of the case made of some sort of laminated plastic. No doubt to survive the tropics.
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The wiring is immaculate. So much so, I suspect it's been rewired. If so, someone did a fantastic job!
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I recall the wiring in the 177 I had years ago look just like this.
What do you guys think - has it been wired ?
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I carefully removed the 83 tube and let it warm up for 20 minutes before testing. That allows the mercury to vaporize.
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Unfortunately, I'll have to replace the power cord before I can power it up. Nice cast aluminum plug housing.
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Here are two fantastic website I found for the I-177 on calibration (http://tubesound.com/2009/09/07/signal-corp-i-177-tube-tester-calibration/) and manuals, schematics and tube settings (http://www.jacmusic.com/Tube-testers/Hickock/IL177/).

I didn't get the MX-949 adapter with mine, but it looks fairly easy to make one. Alternately, there are instructions for simple adapters for tubes like the 12AU7, 12AX7 etc.

I found a computer power cord the same diameter, cut the ends off and wired it in.
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I like how the power transformer has four padded feet. That makes it very easy to work on. I set all the controls to their "safety" positions as indicated in the manual and turned it on.
It's alive :banana:
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After letting it warm up for a while, I set it up to test a 6J6. I'd rather fry one of these than a more valuable tube if something goes wrong.
It passed all tests with flying colors. I'm amazed at how well calibrated this device is after all these years. Probably due to the use of precision wirewound resistors.
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Next, I tested a 24A. I'm not crazy about the grid cap clip. I takes a lot of pressure to open and that thick rubber insulation gets in the way. Much easier to use with it pulled back.
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I've been slowly collecting some early globe tubes for my radios - 182B, 42 globe, 484, etc. I've only been able to test them in an emission tester so far. Now, I can really put them to the test. Here's a 42 globe. I need a matched pair for my Philco 15DX.
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A perfect score of 2,000 :D
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Finally, if it were about to fall into enemy hands...


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Nice find! It certainly looks rewired, but I wonder why they would have had to do that? It's not a task I would embark on unless absolutely necessary.

Thanks. I just found out that they made these up until about 53/54 and this is the original wiring.

What got me thinking it was rewired is that I picked up a couple tube testers at a hamfest back in the mid 80s. A similar I-177 and a Triplett 3413-B. Both had nearly every single wire in them clipped.
I think this was done to "decommission" them before liquidating them to the public. I spent many hours wiring them so thought someone may have done the same to this one.

The wires in your unit were probably ...upgrades made by NARF Alameda as part of a Vietnam-era push to use more of the "still useable, but antiquated" test and measurement equipment. There was an acronym for the program, but I can't recall it off the top of my head, but something like REFIT or REMIT. Vietnam war spending was eating into the DoD budget (sound familiar?) and Uncle Sam "reworked" a lot of test equipment to save acquisition costs. Even when they had to buy stuff, it was only DoD-modded civilian stuff to save on the design cycle. (TV-7's for example - proven design, just upgrades, hence the /A, D/U, etc.) The military cardamatic tube test sets were Hickok and RCA designs, only ruggedized and with 60-400 cycle, hermetically sealed power transformers.

Demil stuff went wa-a-y beyond cutting wires. Axes and sledges are the only two electronic demil tools I've ever seen. Chainsaws for aircraft fuselage use, and stuff that goes boom for rolling stock (tanks, etc).

Having worked on several of those tube testers in the Navy (we're talking my USS Forrestal cal lab days), it seems almost all of them had the NARF Alameda decal on the inside. It would've been a square decal, about an inch or so square with a round logo and NARF Alameda printed on it. They, and Redstone Arsenal reworked most of the GPETE (Gen Purpose Electronic Test Equipment) for the DoD. While most of the stuff was improved, some test sets got the Kapton-insulated wiring, which degrades under exposure to heat and hydraulic fluid. One fuel quantity test I worked on (after being reworked by Alameda) had to have several hundred wires replaced - no easy task when the new wire was PTFE coated, stiff, and hard as heck to strip.

Ah, those were the good days - when we were fighting a known, understood bunch of commies - and test equipment had a 30 year support cycle. Try buying multiple piece-parts for a 90's-era Tek or HP scope...

Cheers,

Wow! Thanks for all the great info :yes:
Now I'm even more curious why someone clipped all those wires. I still have the 3413-B and will dig it out to show you guys what I'm talking about.

Nice! I have the same tester, made by supreme instruments, that I bought from a local man for $50. Most of the tube chart pages are missing and the shorts lamp bulb is gone.

Here's a spreadsheet (http://www.jacmusic.com/Tube-testers/Hickock/IL177/i177_108.xls) of settings for darn near every tube. There are also instructions for making simple adapters for common tubes like the 12AU7.

This guy (http://cgi.ebay.com/No-81-NE-45-Hickok-I-177-Shorts-Main-Fuse-Lamp-Bulb-Set-/350368667401) sells the shorts and fuse lamps.

Guts look healthy! I have an I-177-A made by Munston Mfg. and Service, Inc. Tube chart TB is dated 1946. Was made for the U.S. Army Signal Corps. Works good and is handy for checking older tubes.

As you have probably figured out by now, you have the 1952 version of the I-177, made for the US Army. Clearly it was obsolete at the time, but when the US went to war in Korea, we basically fought with World War 2 surplus. And sometimes the military found out that they had sold off needed things in the late 1940s, and had to reorder them (at great expense, mind you).

I sold the MX-949/U adapter a long time ago. I do not miss it - they are a pain to use.

--
Will

Guts look healthy! I have an I-177-A made by Munston Mfg. and Service, Inc. Tube chart TB is dated 1946. Was made for the U.S. Army Signal Corps. Works good and is handy for checking older tubes.

Yes, it's working very well with my older tubes :) I have other testers I can use for newer tubes.

As you have probably figured out by now, you have the 1952 version of the I-177, made for the US Army. Clearly it was obsolete at the time, but when the US went to war in Korea, we basically fought with World War 2 surplus. And sometimes the military found out that they had sold off needed things in the late 1940s, and had to reorder them (at great expense, mind you).

I sold the MX-949/U adapter a long time ago. I do not miss it - they are a pain to use.

--
Will

Yes, I finally noticed the 52 on the nameplate and on the manual :o

I had a feeling the MX-949/U is a pain with all those patch cords.