Dear colleagues, I'm not Polish but I'm as passionate about electronics as you are. Because I received several EBL21 tubes, I'm looking for a schematic (or links) for a tube amplifier with EBL21 used in Push-Pull mode. I have searched on the internet but I didn't find, only SE mode. If you can...

Radio AGA Special Version for many Speakers line.

Thank you for the link. Do you have the specifications about output transformer? It must have been manufactured.

Unfortunately. I do not have the parameters of this transformer. And we are unlikely to find them. There were few copies of this radio receiver. One, maybe the only one, has my friend. I revived him. Works.

The EBL21 lamp has very similar parameters to the 6V6 lamp. It can easily work with PP Ra = 9kohm and Ra = 10kohm transformers. For less excessive applications it seems possible to use PP transformers dedicated to EL84 / 6AQ5 with Ra = 8kohm.

The diagram in # 5 lacks the grid polarity in the phase inverter (pin 7). The diagram in # 5 lacks the grid polarity in the phase inverter (pin 7).

Buddy, WP! Thank you for being careful and for correcting the mistake. It never occurred to me that such a solid source of information could allow for such an elementary oversight, good science for the future - Trust him, but check!

And you are convinced that in this system it is needed, compare a similar system diagram on page 18. Regards.

Well, the net cannot hang in the air. There must be a resistor in the grid.

After all, it is between the grid and the ground with a value of zero ohms. I can assure you that there is no error in the schematic, it will work as is.

Well, it is not. It is infinite. In this arrangement, the mesh should be a little (1 - 2 volts) below 1/2 ua. So a divisor of e.g. 1 M +10 k / 1M between Ua and mass. Then the grid will be approx. (-) 1.5 V to the cathode and will not 'float'.

2 classic variants of this type of phase inverter circuit.

EBL21 Push-Pull Tube Amplifier: Schematics, Links, and Information for EBL21 Tubes

22euu 6195 16

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#1 19611521 16 Sep 2021 15:49

22euu 22euu

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Post #1
19611521 16 Sep 2021 15:49

Dear colleagues,

I'm not Polish but I'm as passionate about electronics as you are. Because I received several EBL21 tubes, I'm looking for a schematic (or links) for a tube amplifier with EBL21 used in Push-Pull mode. I have searched on the internet but I didn't find, only SE mode.

If you can help me with a link or information I will appreciate it.

Thank you in advance!
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#2 19611576 16 Sep 2021 16:29

jozgo jozgo

Level 42
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Post #2
19611576 16 Sep 2021 16:29

Radio AGA Special Version for many Speakers line.

Attachments:

AGA RSZ-F-8W.png Download (2.53 MB)
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#3 19611590 16 Sep 2021 16:36

jozgo jozgo

Level 42

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Post #3
19611590 16 Sep 2021 16:36

https://www.oldradio.pl/karta.php?numer=46
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#4 19611601 16 Sep 2021 16:46

22euu 22euu

Level 2

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Post #4
19611601 16 Sep 2021 16:46

Thank you for the link. Do you have the specifications about output transformer? It must have been manufactured.
#5 19611624 16 Sep 2021 17:01

aksakal aksakal

Tube devices specialist

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Post #5
19611624 16 Sep 2021 17:01
#6 19611656 16 Sep 2021 17:24

jozgo jozgo

Level 42

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Post #6
19611656 16 Sep 2021 17:24

22euu wrote:
Do you have the specifications about output tranformer? I

Unfortunately. I do not have the parameters of this transformer. And we are unlikely to find them. There were few copies of this radio receiver. One, maybe the only one, has my friend. I revived him. Works.
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#7 19613947 17 Sep 2021 22:47

aaanteka aaanteka

Level 42

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Post #7
19613947 17 Sep 2021 22:47

The EBL21 lamp has very similar parameters to the 6V6 lamp. It can easily work with PP Ra = 9kohm and Ra = 10kohm transformers.
For less excessive applications it seems possible to use PP transformers dedicated to EL84 / 6AQ5 with Ra = 8kohm.
#8 19671042 23 Oct 2021 21:29

pawlik118 pawlik118

Level 33

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Post #8
19671042 23 Oct 2021 21:29
#9 19671088 23 Oct 2021 21:46

W.P. W.P.

Computer PSUs specialist

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Post #9
19671088 23 Oct 2021 21:46

The diagram in # 5 lacks the grid polarity in the phase inverter (pin 7).
The diagram in # 5 lacks the grid polarity in the phase inverter (pin 7).
#10 19671882 24 Oct 2021 13:39

aksakal aksakal

Tube devices specialist

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Post #10
19671882 24 Oct 2021 13:39

Buddy, WP! Thank you for being careful and for correcting the mistake. It never occurred to me that such a solid source of information could allow for such an elementary oversight, good science for the future - Trust him, but check!
#11 19671910 24 Oct 2021 13:54

cirrostrato cirrostrato

Level 38

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Post #11
19671910 24 Oct 2021 13:54

W.P. wrote:
The diagram in # 5 lacks the grid polarity in the phase inverter (pin 7).
And you are convinced that in this system it is needed, compare a similar system https://frank.pocnet.net/sheets/046/e/ECH21.pdf, diagram on page 18. Regards.
#12 19672074 24 Oct 2021 15:21

jozgo jozgo

Level 42

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Post #12
19672074 24 Oct 2021 15:21

cirrostrato wrote:
And you are convinced that in this system it is needed,

Well, the net cannot "hang in the air". There must be a resistor in the grid.
#13 19672083 24 Oct 2021 15:24

cirrostrato cirrostrato

Level 38

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Post #13
19672083 24 Oct 2021 15:24

jozgo wrote:

cirrostrato wrote:
And you are convinced that in this system it is needed,

Well, the net cannot "hang in the air". There must be a resistor in the grid.
After all, it is between the grid and the ground with a value of zero ohms. I can assure you that there is no error in the schematic, it will work as is.
#14 19672261 24 Oct 2021 17:05

jozgo jozgo

Level 42

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Post #14
19672261 24 Oct 2021 17:05

cirrostrato wrote:
between the grid and ground of zero ohms.

Well, it is not. It is infinite.
In this arrangement, the mesh should be a little (1 - 2 volts) below 1/2 ua.
So a divisor of e.g. 1 M +10 k / 1M between Ua and mass.
Then the grid will be approx. (-) 1.5 V to the cathode and will not 'float'.
#15 19673129 25 Oct 2021 06:26

aksakal aksakal

Tube devices specialist

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Post #15
19673129 25 Oct 2021 06:26

2 classic variants of this type of phase inverter circuit.
#16 19673191 25 Oct 2021 08:16

cirrostrato cirrostrato

Level 38

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Post #16
19673191 25 Oct 2021 08:16

jozgo wrote:

cirrostrato wrote:
between the grid and ground of zero ohms.

Well, it is not. It is infinite.

We are talking about the same mesh (pin7) of the heptode part of ECH21 in the last photo?
#17 19673202 25 Oct 2021 08:25

pawlik118 pawlik118

Level 33

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Post #17
19673202 25 Oct 2021 08:25

jozgo wrote:

cirrostrato wrote:
you are convinced that it is needed in this system,

Well, the net cannot "hang in the air". There must be a resistor in the grid

I think you are talking about two different patterns.
My schematic from ECH21 in which the heptode part works as a voltage amplifier is alive copied from the ECH21 documentation according to the link above.
The negative voltage of the grid pin 6 will be used for voltage gain control (the lamp is a selectode).
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Topic summary

The discussion revolves around the search for schematics and information regarding the EBL21 tube used in a Push-Pull amplifier configuration. A user expressed difficulty finding relevant resources, as most available schematics pertain to Single-Ended (SE) configurations. Responses included links to specific schematics and diagrams, as well as discussions on output transformer specifications, suggesting that EBL21 tubes have similar parameters to 6V6 tubes, which can work with Push-Pull transformers rated at 8kΩ to 10kΩ. There were also technical clarifications regarding grid polarity in phase inverter circuits and the necessity of resistors in the grid to prevent floating voltages.
Summary generated by the language model.