Electron Engine ™
Printed Circuit Boards by Emissionlabs
Introduction (You are here)- Use of Triode Board (EE12) with Power Supply EE11
- Use of Triode Board (EE12) with external Tube Tester
- Use of Pentode Board (EE14) with Power Supply EE11
- Tube Data Table
- Typical Test sequence
- About the purpose of burn in.
- Fusing of the boards.
- Building instructions
- Options and Support
Tube Test System EE12 Version3. Introduction.
Building this burn in system is really a nice project, and we took out time to document this in detail, and help you understand how and why burn in is done.
Though the boards and documentation looks complex, the functioning is not difficult. Also, the boards are generally very forgiving in case of a mistake.
Dimensions
- EE11 Power Supply Board: 61x 146 mm.
- EE11 height: Reserve appr 60mm for the ring core transformer
- EE12, EE14, EE15 Tube Boards: 127 x 193 mm. .
The Version V3 is similar to V2. Differences are:
- All LEDs are now mounted on the EE12 PCB, to make building easier.
- Additional fuse was added to the power supply board.
- PCB transformer coils have been added for improved RF decoupling.
- The version V3 works can work on AC and on DC voltage for the grid and anode.
A good example of what to do with tubes, stored in their 70 years old boxes, is found in the Raytheon 5755 datasheet (from www.4tubes.com). They write on page 2, note 2, this message: 'Tube data is only correct after 150 hours of burn in, using a typical circuit for that'.
So you see, from the Raytheon data sheet, burn in is not only warming up the heater some hours.
Click here to read some background information about the Raytheon test circuit, which idea we adopted in the burn in device.
Test System EE12, pictured here is Version2. Version3 has the LEDs for 6.3V /12.6V integrated in the tube test PCB. For the rest the PCB is the same.
Please note, the final build needs a cover to make it safe.
This is a modular tube test and burn in system. We sell this product is a kit. We supply the bare PCBs and most of the parts. It consists of:
- EE11. Power supply board with transformer, for 1...3 of the following boards (Ready product):
- EE12 Test Board, for 10 double Triodes like 12AX7, ECC88, etc. (Ready product)
- EE14 Test Board, for 4 pentodes like KT88, EL34, 6L6 etc. (For sale End of 2023)
- EE16 Test Board, for 2 Octal rectifiers under maximum output power. (For sale End of 2023)
The main purpose is to burn in the tubes and do functional testing. Each board is capable to burn in the tubes, and while doing so, observe plate current, for all tube sections simultaneously, by means of LED indicators for the current.
It has to be said, only one tube type at a time can be tested. If for instance a configuration is made of 1x EE12, 1x EE14, only one board can be used at a time, because test voltage is set the same for all boards. The rectifier board can be used independent. When testing power tubes, the power output is limited at 100 Watts. This would be sufficient to burn in one quad of pentodes under high power, or an octet under medium power (recommended), using two EE14 boards.
With three EE12 boards, a maximum of 60 tube sections can be observed simultaneously, while burning in the tubes, and observe if and how they change.
The interesting situation is, we do not really need to know tube curves, or data measured within 1%, to say what are good tubes, and what are bad tubes. Reason is simply, they have already been tested by the manufacturer. This is the basic philosophy, which is explained over two pages, in the Blue Book, of the Max Funke, who spend his entire life building tube testers.
All we want to do, is bring long time stored tubes, or new production tubes, in the intended condition. If a tube has a fault, that will be typically seen when it performs different from the others. Such a difference may go away during burn in, or may get worse even. Or, the whole lot goes down in performance, during burn in. Sadly, such tubes are around also, but it is better to know this anyway. Generally however, burn in will clean the tubes, activate the getter, reduce noise, and almost any kind of problem has a good chance to go away. Like Raytheon says, give it 150 hours.
Grid current can be pre-tested and also monitored during burn in, for 10 tubes together on one board. Though grid shorts are rare, this can cause quite some trouble. Historical tube testers use a neon lamp for this, but I am sure they would have used an LED if these would have been available at the time.
Some possible tubes to burn in
5687, 5751, 5965, 6060, 6072, 6211, 6201, 6414, 6679, 6681, 6829, 6922, 7025, 7062, 7308, 7728, 8514, 6AQ8, 6CG7, 6DJ8, 6DT8, 6N1P, 6N2P, 6N6P, 6N11, 6N23P, 12AT7, 12AU7, 12AX7, 12AY7, 12BH7, 12DT8, A2900, CV455, ECC81, ECC82, ECC83, ECC85, ECC87, ECC88, ECC99, ECC186, ECC189, ECC801S, ECC802S, ECC803S, E81CC, E82CC, E83CC, E88CC, E182CC, M8162. Complete list here
With some adapters sold on Ebay by the Chinese.
WIth 6SN7 to ECC82 adapter: 6H8C, 6H9C, 6SN7, 6SL7, 12SN7, 12SX7, 12SL7, ECC33, 5691, 5692, 6180.
With ECC808 to ECC83 adapter: ECC808