Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives
Support This Site: Contributors :: Advertise


It is currently Sep Mon 23, 2019 12:02 pm


All times are UTC [ DST ]





Post New Topic Post Reply  [ 18 posts ] 
Author Message
 Post subject: Are NOS tubes good to use?
PostPosted: Aug Sun 18, 2019 12:19 pm 
Member

Joined: Aug Sat 19, 2017 6:55 am
Posts: 149
Location: Glendale, AZ, USA
I wouldn't think anything could get old with them, but I am not an expert.
Thanks,
Russ

_________________
Unless other wise noted, I am only interested in the electronics, not what it looks like. Thanks.


Top
 Profile  
 
 Post subject: Re: Are NOS tubes good to use?
PostPosted: Aug Sun 18, 2019 12:39 pm 
Member
User avatar

Joined: Jan Mon 18, 2010 2:13 am
Posts: 18890
Location: Dayton Ohio
Of course! :D They are the best ones to use as they've never been used.

Vacuum tubes don't go bad just sitting around. That is unless they develop a small leak somewhere.
I have seen tubes damaged by excessive moisture. The wires corrode as they enter the stem or base and crack the glass allowing air inside.
Somewhere I have a dud 45 that this happened to, as well as a group of brand new NOS WE316 UHF triode doorknob tubes. :(

Also, sometimes in rare cases it takes a little time for a tube to "wake up". This is especially true of CRTs that have been sitting around not being used for years, but this normally happens to used ones, not much with NOS.

-Steve

_________________
Radio Interests
-Zenith
-Sparton
-Pre-War FM
Consoles and floor models, the bigger, the better!


Top
 Profile  
 
 Post subject: Re: Are NOS tubes good to use?
PostPosted: Aug Sun 18, 2019 12:42 pm 
Member

Joined: Aug Sat 19, 2017 6:55 am
Posts: 149
Location: Glendale, AZ, USA
Thanks.
I thought that, but wanted to make sure I wasn't overlooking something.
Russ

_________________
Unless other wise noted, I am only interested in the electronics, not what it looks like. Thanks.


Top
 Profile  
 
 Post subject: Re: Are NOS tubes good to use?
PostPosted: Aug Sun 18, 2019 1:26 pm 
Member
User avatar

Joined: Dec Tue 01, 2015 5:31 am
Posts: 2249
Location: Columbus Ohio
A lot of tubes off no better choice as they are no longer made. Used tubes require checking for shorts before using but can be just fine.
Personally, I check all tubes before using for shorts and basic gas emission test, then plug it in and see how it performs for whatever device you have it in.
Amps with 4 outputs tubes, like 6V6GT, don't need to be "balanced" but may require swapping positions to get an audible balance that sounds good.

_________________
Joe - There's no shortage of cruelty to animals: http://joinASPCA.org


Top
 Profile  
 
 Post subject: Re: Are NOS tubes good to use?
PostPosted: Aug Sun 18, 2019 8:42 pm 
Member

Joined: Jun Fri 19, 2009 6:34 pm
Posts: 8700
Location: Long Island
While researching some companies that bought and used NOS military surplus tubes back in the 1950s, I came across references to the fact that those tubes were considered highly variable and had to be tested before they could be put into use. After all, most NOS tubes have been moved from one storage place to another a number of times over the years. It’s also not out of the question that a NOS tube was defective in manufacture and it went unnoticed until now when somebody finally tries to use it.

So yes you should test NOS tubes before using them to make sure they’re okay. If they check leaky or gassy it may be because the getters have been inactive for many years. Allowing the tube to warm up by leaving it on the tube tester with the heater on but no other tests active, will often allow the getter to reabsorb the gas, then the tube will be okay again.

_________________
"Hell, there are no rules here--we're trying to accomplish something!"

Thomas A. Edison


Top
 Profile  
 
 Post subject: Re: Are NOS tubes good to use?
PostPosted: Aug Sun 18, 2019 10:06 pm 
New Member

Joined: Aug Wed 07, 2019 7:04 am
Posts: 22
If NOS can be bought go for it but as already remarked it can still be a bit of a gamble. About 30 yrs ago bought a couple of triode 30's for a regen project, only used them for a few months and then put the radio aside for nearly 15 yrs stored in a box.

Only a week ago took the regen radio out an powered it up only to find one of the 30's had failed. Filament ok can only presume it had gone gassy or some other malady.

Pays to have a few spares I think.


Top
 Profile  
 
 Post subject: Re: Are NOS tubes good to use?
PostPosted: Aug Tue 20, 2019 11:10 pm 
Member

Joined: Jun Sat 09, 2007 8:14 am
Posts: 3780
Location: Florida
NOS tubes are no good and may be dangerous. Carefully pack and ship them to me for proper disposal.

RRM


Top
 Profile  
 
 Post subject: Re: Are NOS tubes good to use?
PostPosted: Aug Tue 20, 2019 11:28 pm 
Member
User avatar

Joined: Jan Mon 18, 2010 2:13 am
Posts: 18890
Location: Dayton Ohio
Interesting comments, in all the years I've been collecting, I've had very few problems with NOS tubes.

I will admit I do test them anyway.

-Steve

_________________
Radio Interests
-Zenith
-Sparton
-Pre-War FM
Consoles and floor models, the bigger, the better!


Top
 Profile  
 
 Post subject: Re: Are NOS tubes good to use?
PostPosted: Aug Wed 21, 2019 12:08 am 
Member

Joined: Sep Tue 15, 2015 1:16 am
Posts: 621
Location: 18424 PA
They do go bad. Air gets inside. Bases become separated due to the glue drying out. Pins corrode. Do not trust any tube as working without a visual inspection first, mechanical inspecting, then tested on a tester and/or working circuit. Beware of shorts, gas/leakage tests are performed properly.

If there's no original box, do not pay for a new tube, consider it used. Beware of sellers advertising as "test as NOS". Many new tubes will read over 100%, so a used tube may read 100% does not mean it is new, it could be used.


Top
 Profile  
 
 Post subject: Re: Are NOS tubes good to use?
PostPosted: Aug Wed 21, 2019 12:03 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 1195
Location: Cedar Rapids, Iowa, USA
I have seen a couple of tubes that had faulty soldering of the base pins, so that the connection to the tube element was not made. I would suppose surplus JAN tubes would be statistically better, having been made under the watchful eye of government inspectors. Even so, there has been a span of about 75 years for unused tubes to be damaged through rough handling and the earlier mentioned environmental effects. Attics, basements, and barns are not the best places for long-term storage.


Top
 Profile  
 
 Post subject: Re: Are NOS tubes good to use?
PostPosted: Aug Wed 21, 2019 1:21 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 14725
Location: Fernandina Beach, FL
Keep in mind that the reason this "NOS" tube is still around could be that it was less than perfect when new, as tested by the technician in the shop. It may have been put back in the box and shoved on the shelf.

I bought an NOS CRT for my Admiral 26R12 Bakelite television. I was able to find this on the auction site and it was reasonably priced. It tested new and works just fine. However, when looking carefully at the screen, I found a couple tiny spots that are missing phosphorus. It is barely noticeable and I am not really upset or concerned. But I suspect it was installed in a set and found to be slightly below perfect, put back in the box and stored away. I may be completely wrong.

I bought four NOS 7027A tubes, all in the same type of box, all with the same date codes. However, one had an HK short. So, unfortunately, it is in the "target practice" box of tubes.


Just a theory...

_________________
Don


Top
 Profile  
 
 Post subject: Re: Are NOS tubes good to use?
PostPosted: Aug Wed 21, 2019 4:27 pm 
Member
User avatar

Joined: Jan Mon 18, 2010 2:13 am
Posts: 18890
Location: Dayton Ohio
However you look at it, a NOS tube has a better chance of being good than a used tube.

Whether NOS or used, they are all subject to the same environmental conditions which can affect them.

There are many restorers which will get a radio and not check the tubes before restoring it. Then if there is a problem with one, replace it then.

I'm not in that camp. I check them first before proceeding. I usually only replace them if I find a short or gas. Emission isn't as important unless it is extremely low. Chances are they will work just fine even if in the "bad" section of the scale of a tube tester.

Just my 2 cents, take it or leave it.

-Steve

_________________
Radio Interests
-Zenith
-Sparton
-Pre-War FM
Consoles and floor models, the bigger, the better!


Top
 Profile  
 
 Post subject: Re: Are NOS tubes good to use?
PostPosted: Aug Wed 21, 2019 5:22 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 14725
Location: Fernandina Beach, FL
azenithnut wrote:
However you look at it, a NOS tube has a better chance
Just my 2 cents, take it or leave it.
-Steve

I also agree with Steve in every aspect!
Just my 2¢ too, take it or leave it! (pun intended ;))

_________________
Don


Top
 Profile  
 
 Post subject: Re: Are NOS tubes good to use?
PostPosted: Aug Wed 21, 2019 6:29 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 5550
Location: Montvale NJ, 07645
Probably the biggest enemy of NOS tubes is the way they were handled over the years, and that is why they should be thoroughly tested before using or selling.


Top
 Profile  
 
 Post subject: Re: Are NOS tubes good to use?
PostPosted: Aug Thu 22, 2019 12:23 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 14725
Location: Fernandina Beach, FL
Scott wrote:
Probably the biggest enemy of NOS tubes is the way they were handled over the years, and that is why they should be thoroughly tested before using or selling.

And a hearty agreement with Scott as well. Corrosion on pins... Not good!

_________________
Don


Top
 Profile  
 
 Post subject: Re: Are NOS tubes good to use?
PostPosted: Aug Fri 23, 2019 4:15 pm 
Member

Joined: Oct Thu 04, 2018 2:11 pm
Posts: 132
Location: Suburban Chicago
Any given NOS tube could be better or worse than the one you are trying to replace or the used tube you are also considering as a replacement. That's just life. A tube tester can help with your decisions if you have the opportunity to use one before you buy. Ultimately, as is often said here, your radio is the best tube tester. Unless you are building a guitar amp new tubes are unlikely to be an option although in some cases popular guitar amp tubes are also used in radios of course.

So far I have had a lot better luck with NOS and used tubes than with the tubes found in the radios I have purchased. But I do not have vast experience with either. As it happens I am also building a (bass) guitar amp and the new tubes I have purchased for that test great. I have not finished the amp yet so the final judge of their worth has yet to voice its opinion!


Top
 Profile  
 
 Post subject: Re: Are NOS tubes good to use?
PostPosted: Aug Sat 24, 2019 4:33 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 758
Location: dayton oh usa
even when these tubes were fresh off the line there were lots of duds we got to deal with.
worst for this was the 6gh8.
i have seen 25% fail rates from new in some lots.
so even if the NOS tubes truly are NOS you still face the defect rate from that particular lot.
and on top of that failures from sub optimal storage conditions,mishandling,ect.


Top
 Profile  
 
 Post subject: Re: Are NOS tubes good to use?
PostPosted: Aug Sun 25, 2019 1:34 am 
Member

Joined: Aug Sat 19, 2017 6:55 am
Posts: 149
Location: Glendale, AZ, USA
Thanks, everyone.

I know from my car projects that NOS can mean the part was a second off the assembly line. Or worse. :shock:
Hence my original question.

I am somewhat between a rock and a hard place here. I don't have even a basic tube tester. I was going to get a cheaper one, then upon reading here and elsewhere discovered that those are pretty much not worth buying. I am not in a position to buy a decent tester right now. So I have no way to test any tubes other than in service. And since I don't know if the chassis I am working on are good or not, well.......

Plan is to buy new or NOS when possible, from reliable sellers, for now, and hope that they have tested them. Once I have a couple of chassis working, then I can be a little more open to buying tubes since I could test them functionally at least.

Russ

_________________
Unless other wise noted, I am only interested in the electronics, not what it looks like. Thanks.


Top
 Profile  
 
Post New Topic Post Reply  [ 18 posts ] 

All times are UTC [ DST ]


Who is online

Users browsing this forum: N2LXM and 5 guests



Search for:
Jump to:  




























Privacy Policy :: Powered by phpBB