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NE1U
06-29-2006, 08:59 PM
Back in the sixties when I worked in a Cal Lab we used to yank all the Sylvania Tubes from the brand new scopes coming in from Tektronix and HP and replace them with Telefunken's. We would then turn the scope on, lower the intensity of the horizontal sweep on the CRT and let it sit for a length of time (I've forgotten how long). We called this procedure "burning in". After the time period was over (usually the next day if I remember correctly) we would then calibrate the scope, put a sticker on it (good for 3 months) and send it out to whatever Dept it belonged to. My question is....Is burning in a set of new tubes becessary? I'm asking because I just put a brand new set of 17 tubes in my HQ-180A.
Also, we used to have long wooden Q-tip type thingies for cleaning in betwwen IF cans, Tubes etc. They were about 6" long and were identical to a normal Q-Tip except for the length. Does anyone know if these are still available?

Thanks All, 73 NE1U

KA4DPO
06-29-2006, 09:04 PM
It used to be common practise to burn tubes in. Burning them in allows the getter to do it's job and the plate and cathode resitances will also settle after a few hours. You don't really have to burn them in but if your going to re-calibrate the receiver I would.

WA9SVD
06-29-2006, 09:26 PM
The "cotton swabs" you mention are called, well, "cotton swabs." You can get them from any medical supply house, or many better equipped "apothecary shoppes" AKA Sav-On, CVS, Walgreens, Rite-Aid, Osco, or whatever is in your area. Obviously, they will be a bit more expensive than the generic "Q-Tip"@ type swab, but they will have a 6" wooden stick, and cotton on only one end. They are typically wound a bit tighter than the double sided swabs; but that's good.
Some electronic stores may carry such swabs also. They aren't JUST for medical uses. You can also ask the local pharmacist if they can order a pack or two for you, if they don't have them on the shelf. Again, they will be a bit more expensive than regular swabs, as the medical ones are usually in a sterile package. OR, you could beg, borrow, or steal (OOPS, No, don't steal!) some from your family physician, or make a deal for a package from his nurse. That's always an option; a doc's office will always have some on hand, but if you use very many, you need to get them by the pack/100, not a few at a time.

BTW, the same swabs are often useful for applying lubricants in hard to reach places! (Sometimes you have to remove some of the cotton to prevent making a mess, though.)

AB3EO
06-29-2006, 09:28 PM
You want cotton swabs.

Try the local drugstore. Johnson and Johnson makes 6" wooden ones.

Or here:

https://webvia.techni-tool.com/VIA/index.jsp

Either search for swab, and you get lots of choices, or try this item number: 292CH850

Get their catalog too, if you like electronic tools.

WB2WIK
06-29-2006, 10:28 PM
There are multiple purposes for burning in tubes, one of which is to simply weed out early mortalities.

For your receiver, I can't imagine how it could help -- or hurt -- anything.

The long cotton swab sticks are in common use in doctors offices and hospitals, less common use at home. Very common for taking DNA samples, so police investigators use them a lot, too...I see them at my local pharmacies, as already stated.

WB2WIK/6

W5JO
06-29-2006, 10:43 PM
Quote[/b] (NE1U @ June 29 2006,07:59)]Back in the sixties when I worked in a Cal Lab we used to yank all the Sylvania Tubes from the brand new scopes coming in from Tektronix and HP and replace them with Telefunken's.
Thanks All, # 73 # NE1U
Makes me wonder if someone in the upper management had Telefunken stock or received a kickback. I can't imagine Tecktronix sending sub quality tubes in their equipment.

And to think, it was uncalibrated???

WB2WIK
06-29-2006, 11:15 PM
Quote[/b] (W5JO @ June 29 2006,15:43)]
Quote[/b] (NE1U @ June 29 2006,07:59)]Back in the sixties when I worked in a Cal Lab we used to yank all the Sylvania Tubes from the brand new scopes coming in from Tektronix and HP and replace them with Telefunken's.
Thanks All, 73 NE1U
Makes me wonder if someone in the upper management had Telefunken stock or received a kickback. I can't imagine Tecktronix sending sub quality tubes in their equipment.

And to think, it was uncalibrated???
There used to be, and still is to some degree, a lot of black magic associated with vacuum tubes.

People swore they could "hear" more or less hiss and all kinds of stuff, based on the tube brands. Tube manufacturers went so far as to sell specially marked tubes with gold-plated pins and such.

My 50 year-old Collins 75A4 has its original tubes in it, from 50 years ago. They're from RCA, and the printing is still quite legible. Never had reason to replace any of them, since the receiver's always worked fine.

K9STH
06-29-2006, 11:50 PM
People didn't realize that most of any particular type of tube (i.e. 6L6) was made by a single company and then "branded" for all of the remaining companies.

Each manufacturer would make certain tubes and then put the others' names on them.

There were exceptions, but, in general, it didn't matter which major brand you purchased, the tube came from the same production line.

Glen, K9STH

W5HTW
06-30-2006, 12:04 AM
Yeah, Glen, that's right. And it applies elsewhere, too. I knew a fellow who worked in a "we won't name it" automobile battery manufacturing plant. The batteries came down an assembly line. No name on them at all. This was in the 1960s, and this guy made ten bucks an hour, incredible pay back then, for sitting on the line slapping stickers on the batteries. Might put one name on 500 of them, or 5,000, and then, same ones coming off the line would get another nam.e

On the other hand, I was the chief electronics tech for a food processing/cannng company, also nameless. We canned diced or sliced carrots, diced or sliced potatoes, bell peppers, corn other vegetable products. I worked on the processing machines, kept them running.

The cans are stamped with a code. No labels, though. A buyer from A&P comes in and wants 10,000 cans of fancy grade chopped carrots. The warehouse pulls the cans from the shelves on pallets, and runs them through a labeling machine. Presto, these are now A&P carrots. But the next batch, from the same canning, gets Safeway labels. And the next batch, still the same carrots, gets Kroger labels. All the same stuff.

Once in a while the labeling operator would overshoot and label a few hundred cans over the purchased amount. Simple. We had a machine that tore the labels off. Then the cans are palletized, and stacked back in the warehouse, no labels.

All the same stuff. In fact, it is said Bill Gates owns every business in America.

My wife would buy clothes online from the various ladies' clothing stores, well know names, also unnamed here. I helped locate them, as all she knew about computers was they go clickity clickity when you are typing. If you visit the main women's clothing online sites, you find down at the bottom of the page, the links to other ladies' clothing sites. All of them are well known names, all of them are represented on all of the web sites, and all use the same software for their catalogs. Yep, Gates owns those, too.

Well, maybe not. I expect to awake one morning and find there is only one car plant in North America, and all the Ford, GM and Studebaker (well, maybe not) are just mail drops in some UPS store somewhere. And that same plant makes golf carts, refrigerators, baseballs, men's shoes, and fried oysters.

The entire world is all one giant company.

Ed

W8JI
06-30-2006, 11:34 AM
Quote[/b] (KA4DPO @ June 29 2006,14:04)]It used to be common practise to burn tubes in. #Burning them in allows the getter to do it's job and the plate and cathode resitances will also settle after a few hours. #You don't really have to burn them in but if your going to re-calibrate the receiver I would.
Small receiving tubes generally have no active getter past the original evacuation process.

As a general rule only transmitting tubes use heat activated getters. They normally have zirchronium coated on the anode in glass tubes, or sometimes use other rare metals near the cathodes.

I turn my receiving tubes on and use them. If they are bad, they won't work. if they are good, they will.

73 Tom

WB2WIK
06-30-2006, 03:27 PM
Quote[/b] (w8ji @ June 30 2006,04:34)]I turn my receiving tubes on and use them. If they are bad, they won't work. if they are good, they will.
That's applying digital logic to vacuum tubes. All 1's and 0's. I'd assign 1=works and 0=doesn't.

As for all tubes coming from the same production lines, well there surely was some of that back in the heyday of receiving tubes, but this wouldn't apply to say Telefunken vs. RCA.

There were a few giant RX tube plants in the US, and a few in Europe. Then there were a couple built in Japan. By the time the "iron curtain" countries (as they used to be called) and China got involved in making tubes, the requirement for receiving tubes was way, way down and so were volumes, and quality went down the "tubes." I had visited probably every major receiving tube plant in the U.S. back in the early 1970s, and some of them were already cutting back on production due to reduced demand.

The largest of all of them was the RCA plant in Harrison, NJ. That was huge and employed several thousand people. They cranked out not only excellent quality tubes but great application notes and even a monthly sheet on "tips for Hams." A lot of hams worked there. Because their volumes were so large, they had implemented ISO9000-like procedures for process control before anyone ever heard of ISO9000. An increase in manufacturing yield of 1% was worth a great deal of money, and the only way to improve yields was to strive for perfect quality, so they did.

But they never made big transmitting tubes there. I visited the RCA power tube plant in Lancaster, PA several times and that's where the big stuff came from. Raytheon had their own tube plant in MA (Waltham?) -- I was there once in the seventies but didn't get the tour.

GE was a separate entity and had their own tube manufacturing. Amperex, Mullard and Philips were often branded various ways and came out of the same factories in Europe (although I recall at one time Amperex was a "made in U.S.A." brand). Siemens had their own tube plant in Germany.

Anyway, it's all history now since almost all those plants are closed. My friend David WB2WND's dad worked for RCA-Harrison for many years and retired when the plant closed. He strongly recommended to me, "Buy all the RCA tubes you can get right now, because 10-20 years from now, nobody in the world will make them this well."

He was right.

WB2WIK/6

KL7AJ
06-30-2006, 03:34 PM
I have better luck burning them out than burning them in. http://www.qrz.com/iB_html/non-cgi/emoticons/tounge.gif

WB7DMX
06-30-2006, 08:09 PM
the only exception to the rule is the famous 6GH8A, which will show shorts and leakage all the time

WA2ZDY
06-30-2006, 08:21 PM
One of my high school teachers, Bob Conroy, had worked in quality control at RCA-Harrison. He had been laid off in time to start teaching school in September 1977.

Mr Conroy was passionate about RCA, QC and tubes. They were the best, they knew it and they were willing to do what they had to do to stay that way.

WA7KKP
07-03-2006, 09:22 PM
From my years in the electronics business, burning in tubes was only done in mission-critical applications, and that was simply to ferret out premature failures.

It was the policy of a major microwave company to send a tech out to test tubes for emission/Gm, replace the weak ones, and then let them run for about 30 days before doing any major alignment to the receiver/transmitters. This afforded the longest life between failures.

Now some very high powered transmitting tubes may be burned in, just to make sure they're okay out of the box (some aren't), but for amateur use, that is a waste of time and energy to plug and unplug tubes, and rebox them. 99.99999% the tubes are okay, and if they aren't, you're not in a life-critical mode (my pardons to those contesters who need their radios working NOW!!!).

Relax, and know that those tubes, used in a ham shack, should last for years.

Gary WA7KKP

WA9CWX
07-03-2006, 10:52 PM
I must add that the information here is top rate.
I have bought / sold tubes for years. RCA was always what I had heard was the best. Now I have a little more information.
Next were the tubes made for the military.

I do not know who made tubes for the military, the 'JAN' tubes, but would love to hear about any history of those.

I still have approximately 8000+ tubes from my 'tube buying' days. Even the old 4 pin ones, many in original boxes.
Like the '80's, etc.

Anyway, as I said, excellent info here guys, Thanks !

K9STH
07-03-2006, 11:20 PM
Although most of the "JAN" tubes were made by the major tube manufacturers sometimes some "fell through the cracks".

There was one manufacturer (I have the name of the company somewhere in my files) that made 10,000 6146W tubes for the military. The company built, delivered, and got paid for the tubes then went "belly up". It was some time before the military actually got around to trying to use the tubes. Frankly, they wouldn't operate on as high a frequency as the AM broadcast band!

I know of a number of those tubes that were tried in the Collins S-Lines and KWM-2 series equipment that were in use on a "front line" basis by the United States Military. The entire stock had to be replaced and since the company was no longer in existence there was no way to even think of recovering any money.

Those tubes still show up on the surplus tube market from time to time (usually at a "very" good price). When I hear the company name it "rings a bell" and I know to "stay clear" of them.

Glen, K9STH

NE1U
07-05-2006, 04:36 PM
A lot of very useful info. Thanks Guys!

I hope we can get our bell rung when Glen remembers who the manufacturer was of the faulty tubes. I'd hate to get stuck with a bunch of bad tubes.

Some people were wondering why we pulled the Sylvania tubes and replaced them with Telefunken's? Because experience showed us that the Sylvania's would break down, go bad or whatever after a much shorter time period than the Telefunken's. I'll bet we threw hundreds in the trash can during my stint in that Lab. (Mostly 6AU6's)

Enjoyed the replys to this thread very much. Thanks again and 73 to all. NE1U

BTW.....Glen, I got my Novice Ticket about the same time you got yours (March 1959 for me and then General Class in Sept of the same year) Call was KN1KJD and then of course K1KJD) I was W6ITG for awhile after the Govt transferred me to Ca and then I was N4AOV while in Fl. Got my Extra ticket in May of 86 while in Ct. and got NE1U.

KB2VXA
07-05-2006, 06:48 PM
Hi all,

Wow, you guys bring back memories and you really know your stuff! Especially Glen, RCA and Sylvania (makers of the 6146W) were tops while GE was made in China and sucked from the git go. I won't knock the country for tubes, other products are some of the best in the world such as a line of transformers I had the distinct pleasure of running QA on. ZERO DEFECTS, not a ONE in thousands tested to ISO 9000 requirements.

Now lemme see, RCA and Western Electric, Two Guys From Harrison?

Anyway, someone out there doesn't know his tubes.

"Small receiving tubes generally have no active getter past the original evacuation process."

What do you think that silvery stuff on the inside of the glass is? It's metallic barium, that little metal thingie behind it is only the flash pan in which the mix is ignited by induction heating that forms the getter on the glass. It's an excellent indicator, white says a broken seal that let air in and dull red indicates heat damage resulting in gas. A slight discoloration may not be particularly meaningfull, only that it has gotten some gas which is why it's called a getter, it gets gas and restores the vacuum.

Today we have something else, to prevent gas take Beano.

K4KYV
07-08-2006, 06:41 AM
According to RCA, thoriated tungsten tubes should be taken through a burn-in procedure before they are first used, and whenever they are placed back into service after a long period of non-use.

They recommend first running the filament at reduced voltage for about 15 minutes. Then increase the filament voltage to normal for 15 more minutes. If the tube is used in class-C, next apply about 75% grid drive for 15 minutes, then run grid drive to full value, and apply plate voltage and tune up the amplifier in the normal manner.

As I recall, if the plate voltage is adjustable, tune the amplifier up at reduced plate voltage first, then gradually increase it to full value.

The purpose of this procedure is to allow the getter to absorb any residual gas in the tube before the tube is operated at full rating. Otherwise, the gas molecules will be accelerated by the plate potential, and many will be deflected back to the filament, and literally sandblast away the thorium coating from the filament. That coating is only one or two molecules thick, so it is easily destroyed, and the tube is useless without it - practially no cathode emission.

KA0GKT
07-13-2006, 12:28 AM
KYV hit it on the head, however, I would add that it is a good idea to gently bring up just about any glass or metal envelope small signal vacuum tube and give it a burn in before use thoriated tungsten filament or not. Many tubes are NOS and have sat on the shelf for years if not decades. Glass envelope tubes do get gassy; a slow warm up and then a burn-in will go a long way towards eliminating infant mortality. I have a multi-tap filament transformer from an old tube tester which I bring up slowly with a variac. Rarely will I lose a filament and rarely do I have problems with gassy tubes folowing the burn-in.

73 DE KAGKT/7

--Steve

KA4DPO
07-14-2006, 05:16 PM
Quote[/b] (w8ji @ June 30 2006,04:34)]
Quote[/b] (KA4DPO @ June 29 2006,14:04)]It used to be common practise to burn tubes in. #Burning them in allows the getter to do it's job and the plate and cathode resitances will also settle after a few hours. #You don't really have to burn them in but if your going to re-calibrate the receiver I would.
Small receiving tubes generally have no active getter past the original evacuation process.

As a general rule only transmitting tubes use heat activated getters. They normally have zirchronium coated on the anode in glass tubes, or sometimes use other rare metals near the cathodes.

I turn my receiving tubes on and use them. If they are bad, they won't work. if they are good, they will.

73 Tom
Maybe you should go back to toob skooll......

Many receiving type tubes have a getter ( or had until it was burned in) especially low MU high output types. Don't take my word for it, check VXA's post.

If your gonna post an opinion that's fine but get the facts straight.

W8JI
07-14-2006, 06:51 PM
Quote[/b] (KA4DPO @ July 14 2006,10:16)]
Quote[/b] (w8ji @ June 30 2006,04:34)]
Quote[/b] (KA4DPO @ June 29 2006,14:04)]It used to be common practise to burn tubes in. #Burning them in allows the getter to do it's job and the plate and cathode resitances will also settle after a few hours. #You don't really have to burn them in but if your going to re-calibrate the receiver I would.
Small receiving tubes generally have no active getter past the original evacuation process.

As a general rule only transmitting tubes use heat activated getters. They normally have zirchronium coated on the anode in glass tubes, or sometimes use other rare metals near the cathodes.

I turn my receiving tubes on and use them. If they are bad, they won't work. if they are good, they will.

73 Tom
Maybe you should go back to toob skooll......

Many receiving type tubes have a getter ( or had until it was burned in) especially low MU high output types. #Don't take my word for it, check VXA's post.

If your gonna post an opinion that's fine but get the facts straight.
That coating inside the tube, once flashed during manufacturing, is all done. Gettering agents only work at high temperature. The little ring you see near the dark or silvery spot on the envelope is what initially held the gettering material. It was fired or ignited by induction heating.

The residual material left over the getter is fired or ignited during manufacture is the coating you see. It is all done being used, and serves no more use.

All this stuff about running small receiving tubes to restore them or degass them is an old wive's tale. You can flash the outer layer off a cathode or directly heated filament-cathode, but that generally would involve operating at excessive temperature for a few dozen seconds or longer and boiling the cathode. Operating at normal voltage does nothing to a receiving tube. If it is bad, it just stays bad. If it is good, it will work.

The ONLY tubes that commonly have active gettering after production are transmitting tubes. Receiving tubes virutally never getter through use. They are either good, or they are bad.

The most common gettering material in transmitting tubes is zirconium. Zirconium is used on the outside of graphite or molybdenum anodes in 3-500Z and other tubes. It is the dull gray powdery or grainy texture coating you see on the surface of 3-500Z, 811A, and 572B anodes.

This material is NOT used in receiving tubes, because they:

1. Receiving tubes don't leak very much. The seals through glass are small and well-sealed

2. Don't have high voltages like transmitting tubes. A 3-500Z has to hold off 6-8kV of peak anode voltage in a typical RF amplifier, and that peak voltage might reach 10kV or higher when mistuned. The smallest amount of gas is devastating to a high power transmitting tube, but not to a 6AQ5 running at 250 volts.

Small receiving tubes do NOT degass with application of filament voltage or during operation. Anyone claiming that is simply making an untrue statement.

Some transmitting tubes degass by running the filament, but as a general rule it is ONLY the external anode tubes have gettering on the filament or cathode structure.

73 Tom

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