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 Really strange tube tester socket & some T/T info

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FrankB
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FrankB

Join date : 2010-11-22

Really strange tube tester socket & some T/T info Empty
PostSubject: Really strange tube tester socket & some T/T info   Really strange tube tester socket & some T/T info Icon_minitimeMay 6th 2019, 7:37 pm

Some of you might run across a tube tester or radio analyzer with a very strange socket on it.
 It appears to be a septal base socket that has many, many holes in it.

Bakelite termites you ask?

 It was designed as a "Universal" test socket for tubes. It would handle many different tubes from the Septal base era (20's & 30's).
 It cut manufacturing costs- one chassis hole vs several and several sockets and rivets saved, plus it required less wire and labor. ($$$ Gotta love those bean counters!)

They were also used on several brands of "Radio Analyzers" also.

They were only used for a very short time, as the Octal tubes then came out, as well as the 7 & 9 pin miniature series.

I had a tube tester that use the octal socket to test loctal tubes.
 From the operating instruction manual:
 "Insert loctal tube in octal socket and rotate tube until the tube pins make contact with the pins in the octal socket, hold in place,  then follow test instructions."

A really cheap way to avoid adding a socket to a tube tester or upgrading the tester. BTW, it really didn't work worth a darn.

Also you might see some blind hole plugs on the front of the test panel on a tube tester. They were often installed during a limited time era when octal, miniature and other "new" tubes were coming out.
 It was an attempt to allow your tester to have newer tube sockets added to the chassis, and you simply wired them in parallel with the existing sockets. This worked fine for up to when the 7 pin miniatures came out.
 But then you ran out of panel switch positions for octals, 9 pin miniatures and newer tubes. (Septal base tubes, remember- 7 large pins) I actually had a tester that had the modification added for 7 pin tubes.

During that era some of the ads for tube testers read: " Obsolete Proof Tube Tester" "You will never have to buy another one again". Suspect clown
"Yeah, check's in the mail..."

When the compactrons, noval, and magnoval types came out the testers couldn't test them.
 Coletronics made an adaptor that plugged into one of your existing sockets on your tube tester, and also connected to the grid/plate cap.
 You would rotate the tube in the adaptor to test various sections of the tubes. The adaptor came with a special set of setup data for it.

 I used one decades ago, and it worked quite well.  However I found it was a real pain in the rump to use because if you managed to get the tube  inserted one pin off, it wouldn't test the tube, you could also damage the tube or the tube tester.  Not to mention the tube could get hot & burn your fingers at times.

Now if you got an old tube tester, you would often get a weird socket on one end of a cable (duodecal socket) and an octal plug on the other.
 This cable was plugged into the octal socket on the tester, and the other end connected to a black & white CRT. Your adaptor would originally have setup instructions with it, and later they were often put on the updates for the roll charts. Basically it checked the CRT for emission & shorts. 
  It did work OK for quick tests of CRT's.

Then some genius came out with another adaptor that used a 6AL7 eye tube in it. If I ever find mine, I'll try to post a pix of it.
 It was plugged into the duodecal socket of a black and white CRT, and you could "see" the signals going to the CRT. A crude piece of test equipment, but quite ingenious in truth. They came in a cardboard "can"
with an instruction sheet. Often it was a help in determining if the CRT was really bad, or a signal fault.
  I remember decades ago when I first started working on TV sets, that one of the techs fought a vertical sync or hum problem in a B&W Zenith TV set for 3-4 days. He subbed all the filters- it looked  like a 60 cycle hum in the pix- and even checked and replaced all the parts in the vertical section to no avail. Then one day he shoved another TV set over to the chassis, and connected the other sets CRT to that chassis. 
WHAM!! No vertical problem or hum bars.  
 Turned out the CRT had internal leakage AFTER the set warmed up.
 He was actually able to ohm the CRT out and watch the short disappear.

 (Don't think this only can happen to CRT's folks. I have seen it more than I like in tubes of all types. Shorted when hot, no short when cold).
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Rod Clay
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Join date : 2018-08-01

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PostSubject: Re: Really strange tube tester socket & some T/T info   Really strange tube tester socket & some T/T info Icon_minitimeMay 8th 2019, 3:54 pm

There was one of those multi-pin tube sockets on an early Hickok "Diamond Point" tube tester I used to have back in my shop at  Lynchburg, Virginia. I tried to avoid using it as much as possible. Maybe the service men back then had a better feel for them. As Frank said you will find sockets like it on early to mid 1930s tube testers. By the late 1930s such sockets had been dropped in favor of separate conventional sockets. RCA's octal socket had made its appearance by 1935-1936 along with Sylvania's competing Loctal socketed tubes.
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FrankB
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FrankB

Join date : 2010-11-22

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PostSubject: Re: Really strange tube tester socket & some T/T info   Really strange tube tester socket & some T/T info Icon_minitimeMay 9th 2019, 7:02 pm

I mentioned the Coletronics adaptor.
 Eico Heathkit, and at least one other company made "Add on" adaptors to test the newer tubes.
 I have an Heath TT1A ("A"  indicates it has the adaptor. It was mounted on the lid of the tester.)
 My Eico 666 teater also came with one. I --think-- I remember Hickok also making an adaptor too.

NOTE: The adaptors were not limited to the "early" equipment to test additional receiving & transmitting tubes.

 One company made a killer universal test adaptor kit that fit my B&K 467 & 468 CRT testers (and many other makes & models) which allowed me to test rear projection CRT's and a massive amount of other CRT's that B&K didn't have in their setup books.
   A truly well engineered kit, AND if you couldn't find a CRT listed in the setup book that came with the kit,you could call the company and they would give you the settings--FOR FREE!! Best customer service ever!! 
  It was truly universal too. It came with the setup book and a whole slew of CRT sockets for different bases, plus the "UA" adaptor, which was a plug fitted with test clips to hook on the CRT pins if you didn't have a socket that would fit a particular tube. I know I added 2-3 more sockets from junked sets to the bag of them.

 I can't remember the name of the company at the moment though. They used to advertise regularly in ES&T (Electronic Servicing and Technician) magazine up to the time it quit producing the magazine. (A massive loss for the servicing industry).
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Rod Clay
Senior Member 75+ Posts
Senior Member 75+ Posts


Join date : 2018-08-01

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PostSubject: Re: Really strange tube tester socket & some T/T info   Really strange tube tester socket & some T/T info Icon_minitimeMay 10th 2019, 8:01 am

I had a B&K CRT tester that came with a number of adaptors. It was a pretty good piece of gear. It covered the more common CRTs at the time. B&K and Sencore sure made a lot of specialized test equipment for service techs back in those days. 

Regarding the tech with the hum bar problem: One time I had two identical tv sets on hand. One had a bad main board and the other had a bad CRT so I did a swap and made one good set out of the two.
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PostSubject: Re: Really strange tube tester socket & some T/T info   Really strange tube tester socket & some T/T info Icon_minitime

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