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Author Topic: "Burning in" tubes?  (Read 42586 times)
KG4ABA
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« on: September 06, 2017, 09:52:46 AM »

I'm about to order some new 572B tubes for my Heathkit amp...I saw where someone "burned in" the tubes for about 10 hours before applying RF to the amp...is this a good or desired practice?  Any thoughts?
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KC4ZGP
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« Reply #1 on: September 06, 2017, 11:49:30 AM »


I'm going to watch this thread. I'm on the hunt for a tube amplifier. Many things to keep in mind versus solid state.
I've seen some Collins 30L-1 beauties on e-Bay.

Wheew!

Kraus
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N8CBX
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« Reply #2 on: September 06, 2017, 12:05:52 PM »

"burned in" the tubes for about 10 hours
They are new. Don't waste your time, it's unnecessary. I just installed two new 572B (chinese) and they are working great.
Jan N8CBX
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Dayton Ohio - The Birthplace of Aviation
W8JX
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« Reply #3 on: September 06, 2017, 12:07:03 PM »

I'm about to order some new 572B tubes for my Heathkit amp...I saw where someone "burned in" the tubes for about 10 hours before applying RF to the amp...is this a good or desired practice?  Any thoughts?

There is nothing to burn in on a 572. It does not getter on filament power alone. I suppose you can let them warm up 5 or 10 minute before first use if you want to but nothing gained doing it for hours. 572's 811's and 3-500's are pretty much instant on tubes and are ready for action within 5 seconds of power on.
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Ham since 1969....  Old School 20wpm REAL Extra Class..
W1QJ
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« Reply #4 on: September 07, 2017, 02:59:51 AM »

I agree that they don't need to be run for any time  before use. However beware  that depending on who you buy the tubes from may have a warranty policy that requires you to follow a procedure for using the tube new.  If you get a bad tube and you aren't aware of the warranty policy that may have some sort of burn in period you'll be denied a replacement tube if you are questioned about doing your burn in.  So although it shouldn't be necessary you should know if there is a hitch to the warranty.  Read it so you are covered.
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W8JX
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« Reply #5 on: September 07, 2017, 06:39:53 AM »

I agree that they don't need to be run for any time  before use. However beware  that depending on who you buy the tubes from may have a warranty policy that requires you to follow a procedure for using the tube new.  If you get a bad tube and you aren't aware of the warranty policy that may have some sort of burn in period you'll be denied a replacement tube if you are questioned about doing your burn in.  So although it shouldn't be necessary you should know if there is a hitch to the warranty.  Read it so you are covered.

As usually good advice but I would add that if vendors had such terms they would be hard pressed to prove you did or did not comply with them other than your word on the matter.
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Ham since 1969....  Old School 20wpm REAL Extra Class..
KM1H
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« Reply #6 on: September 08, 2017, 05:53:44 AM »

Who the heck has such a policy with 811A or 572B's?

I can see it with some indirectly heated tubes where they getter with filaments on only.
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W8JX
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« Reply #7 on: September 08, 2017, 07:03:08 AM »

Who the heck has such a policy with 811A or 572B's?

I can see it with some indirectly heated tubes where they getter with filaments on only.


I agree
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Ham since 1969....  Old School 20wpm REAL Extra Class..
N3QE
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« Reply #8 on: September 08, 2017, 07:39:21 AM »

With all new production 811A's being such low quality I strongly believe there is valuable in doing visual inspection of innards of tubes, a filament-only test, then applying HV.

I have heard (and seen with my own eyes) so many supposedly new 811A's with visibly obvious defects like filaments bouncing around in the glass and anode caps unattached.

If you ohmed out the tube looking for shorts I think there's value to that too (at least you'll save the expense of new primary fuses that you didn't have to blow.) If you can hi-pot test the tube before blowing fuses that's even better.

I'm not sure there's any value in having HV on but waiting to apply RF. If you've got HV on it you may as well give it some RF.
« Last Edit: September 08, 2017, 07:42:13 AM by N3QE » Logged
W8JX
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« Reply #9 on: September 08, 2017, 08:06:49 AM »

With all new production 811A's being such low quality I strongly believe there is valuable in doing visual inspection of innards of tubes, a filament-only test, then applying HV.

Part of the problem is they are expected to be fairly cheap to buy and middle men want to make a larger profit on markup so they want to pay very little for tubes and they end result is you get what you pay for. Also be thankful that even lower quality ones are available because is none were available there would be a lot of amps that are door stops.
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Ham since 1969....  Old School 20wpm REAL Extra Class..
K4RVN
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Posts: 261




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« Reply #10 on: September 09, 2017, 06:16:55 AM »

Lynn,
Tom, W8JI the designer of many Ameritron amps, suggests burning in 572B tubes at 1/3 HV in an article on the net. I just read it again a few minutes ago. Also Kraus if you read this I am going to rename you the highjacker LOL. Quit fooling around and buy you a good used AL 8oB and stick to the subject. I would suggest leaving 572bs on HV for the start up use longer than normal, say 5 minutes to make sure they are warm initially. Also they are not drawing a lot of current during that period with idle HV. Might save you some parts if the tube is defective. I don't know if that is a good idea I just always do it on new RF tubes. Wish Tom was posting as he would tell me in no uncertain terms if what I did was totally wrong and I would believe him. There are others who probably will also and I would believe them.

Frank
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W1QJ
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« Reply #11 on: September 09, 2017, 06:33:19 AM »

Who the heck has such a policy with 811A or 572B's?

I can see it with some indirectly heated tubes where they getter with filaments on only.


I agree

I'm not aware of the "instructions for use" of any particular brand of 811/572B tube.  However I do recall as question or two of someone mentioning that they bought a particular brand of 811/572B tube and saying the instructions said to "burn in" the tube before applying RF to it.  My comment was simply that if the instructions of  ANY particular seller of these tubes require a "burn in" period to comply with the warranty you had better be aware of it before you make a claim of a bad tube.  A scenario:  I buy brand X 811 tubes.  I open the boxes and install tubes in my amp (I don't read the instructions that say warranty requires you follow the instructions) and I then turn   it on and immediately load the amp up.  A tube arcs and shorts out my power supply and ruins my zener diode.  I call brand X on the phone to complain that the new tubes I just bought from them damaged my amp.  Mr Brand X on the phone says "I am very sorry to hear that, how long did you "burn in" the tubes before you attempted to apply RF to them?"  Ham on phone....Oh Um, um, oh, um well, they are 811 tubes, they don't need to be burned in.  Brand X...Did you read the instructions?  They clearly state that the warranty requires you "burn in" the tubes for two hours before applying RF.  I'm sorry, you didn't do that and the warranty on the tube is voided.  Have a nice day.  All I am saying is be aware "IF" there is any instruction requiring something you did not do before you call to ask for a warranty claim.  In other words don't incriminate yourself.  
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K4RVN
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« Reply #12 on: September 09, 2017, 09:22:07 AM »

Lou it was perfectly clear to me on your original post and I'm just half smart maybe.

Frank
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KM1H
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« Reply #13 on: September 09, 2017, 10:44:13 AM »

Quote
I'm not aware of the "instructions for use" of any particular brand of 811/572B tube.  However I do recall as question or two of someone mentioning that they bought a particular brand of 811/572B tube and saying the instructions said to "burn in" the tube before applying RF to it.

So that will now float around in the Internet cloud forever as gospel just because Lou said it.

If there is any truth to that it should have been referenced in your post. One scenario is a dishonest seller uses it as a way to deny warranty on junk tubes which wouldnt surprise me at all.

Quote
I have heard (and seen with my own eyes) so many supposedly new 811A's with visibly obvious defects like filaments bouncing around in the glass and anode caps unattached.

Those curly little things rattling round are the filament support springs and Ive seen plenty of those on NOS and used USA tubes also that were apparently dropped in shipment or by a clumsy handler at some point. Other US tubes, especially from WW2, have very brittle filaments that do not age well over the years. Im still looking for a good and useable 861.
Chinese 3-500's are notorious for a loose anode cap set screw.


Quote
Lynn,
Tom, W8JI the designer of many Ameritron amps, suggests burning in 572B tubes at 1/3 HV in an article on the net. I just read it again a few minutes ago.

Then why didnt you provide a link?
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K0CWO
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Posts: 550




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« Reply #14 on: September 09, 2017, 01:08:33 PM »

https://www.w8ji.com/gettering_tubes_al572b_al80b.htm

Article describes a gettering procedure, not merely applying plate and filament voltage without drive. (If this is the article referred to earlier)
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