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How to choose 6c33b?

S E 6C33C-B

Im in the process of bread-boarding a 6C33 SE amp with home-grown Tx and double Mu input stage. Happily nearing completion of the breadboard stage! (See 'Anyone wound O/P Tx for 6C33B, Thread)

I got my 6C33 from Anthony Welsh on Ebay, these seem fairly well matched and reasonably stable. He sells good quality sockets for them as well, Beware of Chinese versions as they apparently give trouble.............

As with everything, you pays your money and takes your chance, but at least with his prices, you can afford to buy 8 and have a few spares, for the price of two from some vendors!

My 6C's are 1977, Uylianovirsk C-B versions with an OTK number of 17

My idea when I ordered was to ask for some Mid 70's tubes, of the C-B version as I reasoned that any 'rejects' would be of a much later date, and the tubes from the 70's would probably be kosher, being made during the 'Cold-War' period, where rejects would have probably been destroyed, as this valve had little use in the civilian market at the time.

I have tried all 8 valves I have for at least 3 hours each, with no problems with the emission/ageing/or matching All in my cathode Bias amp draw 200mA +- 5mA, Pretty good for such a large bottle!
 
Hi,

I am doubtful that there are any rejects floating around on the market nowadays as original 6c33C's are cheap and easy to come by, but! I know that there where rejects sold as faultfree a few years back.

I have bought 6C33C from both http://www.gstube.com/ at 15 USD each and from http://www.tubes.ru at 18 USD, (they seem to have increased the price to 19 USD recently).

The tubes from both these sources comes in original unopened boxes and I haven't still found any tubes that is a reject in any way, the measure quite similar with actual performance close to the data sheet.

I can recommend any of these companies as the service is quick without any problems whatsoever, there is no reason to pay more for these tubes from a local supplier.

Regards Hans
 
What you guys mean by rejects?

Tubes rejected in the final quality control at the factory due to worse performance than specified, normally these tubes should be scrapped or in some cases sold as a type with less performance.

There is however a risk that rejected components can be sold trough unofficial sale channels as faultfree which gives the original manufacturer bad reputation. This is unfortunately not uncommon in the electronics industry.

Regards Hans
 
I have bought my 6C33C-Bs from http://www.anthonywelsh.com some time ago.
A friend of mine bought them recently from http://www.gstube.com

Even thou the ones coming from the latter looked more “new” the factory logo did not point to Ulianov which is the default factory for them.

I would like to charge something more regarding Welsh (maybe I’ll start a new thread on this). Some weeks ago we have ordered a few GM70s and the ones we received didn’t look like the ones shown on ebay. The getter area has some holes clearly marked by a red sticker pointing them. I suppose the sticker was placed by factory to indicate the failure. Besides that, the shape and condition of all 4 of them was less the satisfying. One of them also failed the heater test.
 
Hi to all,

I am too building a SE with the: 6C33C-B
I bought 8 tubes, and am currently building the heater power supply's
for the Simplex from Ari Polisois.

Idea:
I have bought 2 sets of sockets, and removed the clips from one set to double them on the other set of socket, now I have better contact
from pins of the 6C33C-B to sockets...

Hope to make a proto in a few weeks to test the 6C33C-B plate currents
and be able to make 1 or 2 pairs from the 8 originals... Bought from AntonyWelsh too, the only pb at this time is oxidation on the tube pins...
Used ScotchBrite to polish them...

Regards.

Alain.
 

argo

Member
2001-02-12 3:35 pm
Estonia
Re: S E 6C33C-B

tubetvr said:


Tubes rejected in the final quality control at the factory due to worse performance than specified, normally these tubes should be scrapped or in some cases sold as a type with less performance.

There is however a risk that rejected components can be sold trough unofficial sale channels as faultfree which gives the original manufacturer bad reputation. This is unfortunately not uncommon in the electronics industry.

Regards Hans
OK. “Unofficial sale channels” or in other worlds stolen from factory before scrapping them makes sense.
Because there was no other chance, how the rejected tube would have left the factory.
All tubes carrying an OTK imprint (the following number gives no valuable information per se) should have been checked by the quality inspector of manufacturing factory.

Alastair E said:
...
My 6C's are 1977, Uylianovirsk C-B versions with an OTK number of 17

My idea when I ordered was to ask for some Mid 70's tubes, of the C-B version as I reasoned that any 'rejects' would be of a much later date, and the tubes from the 70's would probably be kosher, being made during the 'Cold-War' period, where rejects would have probably been destroyed, as this valve had little use in the civilian market at the time.

Actually the "Cold-War" period should be the worst production period because it overlaps with the so called "Stagnation Era" in former USSR. The whole country was just plain too drunk of vodka and nobody really cared about production quality, even in the military factories.
But this is just a generalization. There may have been exceptions among the individual workers at charge and production days, weeks or months.
 
Yikes !!
I had a look at those sites.A welsh does not seem to have tube sockets for the 6c33.GS has but they cost as much as the tubes themselves!!!How can that be?
Well 15usd for a power tube ain´t much of course.Less than some puny preamp tubes.
I guess the big square ceramic sockets are a must for this tube?
 
GS has but they cost as much as the tubes themselves!!!How can that be?

Quality maybe, I have used the same 6C33C tubes and sockets in my OTL amplifier now for more than 4 years without changing tubes and without cleaning the sockets, sometimes I have measured the voltage drop between socket connection and tube pin but there is never more than a few mV drop and no problems with bad connection, the sockets I use are original Russian ones, if it is that type that GS sell I think they are probably well worth the price.

Regards Hans
 

argo

Member
2001-02-12 3:35 pm
Estonia
Those are original Russian production as far I can see on the pictures. The pins are silver (Ag) plated and will oxidize pretty badly. Otherwise ceramic body as usual.
I am planning to buy some sockets as well from somewhere. What’s the deal with these Chinese 6C33C sockets?
How will I know buying from an arbitrary web- shop, which ones I will get - the good ones or the bad ones?
I have no experience with other Chinese sockets than octals and novals. They are not perfect but seem work OK.
 
argo,

About the Chinese sockets for the 6C33C-B:

in Post#7:

I have bought 2 sets of "Chinese sockets" {4}, and removed the clips from one set to double them on the other set of socket, now I have better contact for pins of the 6C33C-B to sockets...
{One from PartsConnexion, the other from TubeDepot all "Chinese"}
Now, the tube is perfectly set on the socket!

The major default of these sockets is: the legs are too long, and the clip
is too loosy...

I can make a macro if you need more details...

Alain.
 
The pins are silver (Ag) plated and will oxidize pretty badly

The black oxide like surface is silver sulphide that comes trough the reaction of silver with sulphide iones in the air, if you smoke silver items get even blacker. However this black tarnish on silver doesn't matter much as silver sulphide has almost the same conductance as silver itself, it is not an isolator.

The problems with the "chinese" sockets is that the material is too soft, it is probably just plain brass while the material in the russian sockets is probably phoshor-bronze or something similar, they are much harder and doesn't bend easily.

Regards Hans