Tubes Articles

FAKES TUBESHall of shame - Fake tubes

LASER FAKED - Telefunken Diamonds found.

The ultimate proof of authenticity, the Telefunken diamond <> bottom, is no longer with us. This opens a whole new field for the fakers, because on sites like Ebay, the judgement for what is real or not, is very low. Buyers look only at good feedback of others, but themself they give only good feedback based on quick emotions. They do not understand, products, obsolete since 50 years, can never be on the shelf in quantities of 100's , from several sellers. They all show proudly ultra rare tubes in boxes of 100, on their website.

Naturally, the most faked tubes are those where they can easily get raw material of. Like re-brand RFT ECC81 as Siemens ECC801S, which was common faking practice since decades. So you can even by those fakes in "real" old boxes from 1990 or so, in dusty worn out 100pcs master cartons. The older this gets, the more real the fakes begin to appear. But what they can not fake, is the MOST important property, why TFK ECC801S is so expensive: These are factory specified for maximum 15% off-balance between the two systems inside one bulb. Sorry to bore you with this, but I have to tell this because occasionally some people do never heard about it. (So one system has 10mA, the other 12mA, that is 20% difference, for ECC801S that is a reject). And it is SO EASY to verify, because the seller of course has tested that for you, right? That is because this is the most important piece of tube data. The seller supplies this with the tubes of course. (Oops.... he forgot...I know...). Myself I have not this feedback for the fastest shipment ever, but I ship you good tubes, and you will probably come back later.

I would say you are much better off, checking for good tube data, instead checking for good Ebay feedback. Because the feedback is only for quick shipment and nice communication. Well ok, but I do not have to understand everything :)

Anyway, Siemens fakes ECC801S are history now, since the Telefunken diamond <> has become laser printable, with a real glass melt process. So it is not a coincidence, the offerings of Telefunken NOS <> tubes have exploded, while at the same time market needs have exploded two. Can you seriously explain this miracle?

A box with 100 pcs RFT ECC82 can now easily be converted in NOS Telefunken, with <> diamond bottom.

The Full Story

About mizztakes with tubes.

Article here

The man who predicted the electron

The greatest prediction ever. He did so against all opinions, in a world full of false and wrong theories, which hoplessly tried to explain observations. With scientific instruments of the time, he predicted the electron, with an estimation of it's charge as well.


About Chinese fraud with fakes on ALIEXPRESS

I thought it happens only to others.

Portrait of some interesting tubes. Some broken apart. Some pictured alive.



What is burn in, and why is it needed?

today I see people burn In mains cables, or treat CD with a demagnetizer, and all kind of things which some call break though inventions, and others call it stupid. Article

Advantages of PARAFEED


A noisy amplifier

Very short Article

Using Selenium Diodes



Telefunken ECC803S <>

The Holy Grail of small signal tubes


The lost recipe of ECC803S

EI Tubes factory closure
Game Over for EI tubes.
This is about the famous EI tube factory. Unfortunately most of the equipment was scrapped recently. This was a shameful destruction of an intact tube factory. Read more about it here.

Blue Glow in tubes

Long before vacuum tubes were discovered as electronic devices,  the blue glow of  "not so clean" vacuum was discovered automatically.  All you need is not so good vacuum,  with  a very tiny fraction of air,  and the tube is gets conducting at high voltage, emitting bright pink light.  These were the "Geisler" tubes,  and soon these were used in all kind of variations. 

More information here

Advantages LC filter vs CLC filter


Tube Tester Freeware

Simple help page for Dynamic parameters
You have a good tube tester, but it cannot measure dynamic parameters, like Gm, Gain, or Rp? Well most of the time you can, but you need to make differential measurement.

Instead of having to explain this just use this little Excel Worksheet. You can select the tube you want, or enter the data by hand in the right table.

Then you need to do Measurement 1 + 2 and you have the Transconductance. (Gm). If you also do Measurement 3 + 4 you get in addition the Gain the Plate impedance.

Even so, you can use this program to check the performance of a tester, that is able to test Gm or even Rp and Gain. And no, this sheet makes no errors. Any differences are caused by the tester itself, since there are analog circuits also in digital testers, and even digital, you have the problem of low resolution if cheap A/D converters are chosen, such as in the AT1000. DOWNLOAD HERE.

A mysterious "constant current user"

Or why voltage specified heaters should be voltage driven.
By Jac van de Walle

Computer Aided Testing


More information here

About Tin Whiskers

This is what happens when you use 100% pure tin.

More information here

About Stand by Mode

Stand-by information

OVEN baking of NOS tubes


Oven Baking information

Vintage instruments of my collection.

Some are not easy to replace by modern electronics!

More information here