Electronic Universal Vade-Mecum

[Paul Barker]

The bad news is I can't find Rosenblit book.

The good news is I found my Electronic Universal Vade-Mecum, so if anyone wants a spurious valve looking up that they can't find the data on anywhere else pipe up.

Hi Paul
Don't suppose you can shad some light on the true data of this Russian 6P3S/6n3C cant seen too fine a consistent spec on this valve

some say for example anode voltage is anything from 250/500volt and cathode anything from 44mA to 72+_18 Equivalents of 6L6 6L6GT they say but who knows any ideas
http://ussr-tubes.com/index.php?main_pa ... cts_id=307

The Russian symbol for what you are calling an n looks a bit like pie. It's like two capital I's but the top two outriggers are joined II. I have to be this pedantic because the VAde Mecum lists it by it's proper symbols not by what it has been converted to for the benefit of American dominated internet language. My book predates the internet so it calls things by what they are, not by what Americans think they should become.

It is only listed as an equivalent of the 6L6. All the curves on the relevant page show 6L6 and all the suggested operating criteria are for 6AH5G, 6AL6G, 6L6, 6TP, IILL6, and 1631.

The 6L6 maximums are listed as
Triode connected 275v 12.5 watts anode dissipation.
Tetrode Anode 360v g2 270v 19 watts anode dissipation

As such tetrode connected maximum single ended power out operating point anode 350v g2 250v bias -18v for 10.8 Watts (15% thd)

Triode connected they only show 250v -20v bias which gives a pathetic 1.4 watts at 300v -20v bias it would give 1.8 watts but it is above ratings. (5.5% thd)

Seems a bit pathetic. Your KT66 has

Triode 400v -38v 5.8 watts 7% thd
or 250v -19v 2.2 watts 6% thd

It is often likened to the PX25, so to give you the comparison

PX25 at 400v -31v 3k2 load 6 watts 6% thd
or 500v -45v 5k5 load 8.5 watts 7% thd

tetrode 250v 250v -15v 7.25 watts 9% thd.

Therefore 6L6 is better suited to tetrode operation and kt66 more suited to triode operated, when working single ended.

Push pull is entirely different.

[colin.hepburn]

Yep seem most of the Over ratings for this 6p3s/6l6 are coming from guitar amp sites overdriving them into red plating and ends up with the 6P3S being mixed in as a 6L6 anything so not a lot of help really
I have my 6P3S running @ 320v-24v=13.3 so 24v/554R=43mA so don't really know if I am under or over running them but thay sound pretty good
Maybe I should try them in tetrode operation
Link to data for 6P3S/E that I have found

http://www.tubes.ru/techinfo/HiFiAudio/6p3s.html

[Paul Barker]

Looking at that data you are overstretching the G2 which is 300v max. But the rest is alright. The dissipation of 20 wats is much more than the 6L6.

If that data is correct it is much tougher.

[Paul Barker]

This 35A5 is in a Loctal base with 35v 0.15A heater. But it is electrically a 6L6 cheap NOS valve performs like a 6L6. The guy has 6 of them.
Also look out for 35B5, 35C5, 35L6G, 35L6GT and with 11 volt heater 11C3.

BAsings and pinouts vary. Ask.

these ones are £1.38 each he has 6. But shipping from USA. PErsonally I would buy the six if I didn't have enough 6L6's.

[Paul Barker]

This EL60 is a Loctal EL34

[Paul Barker]

6V6

I am very much liking the 6V6.

I never noticed before the capability in triode mode. Probably because knowledge of triode mode is sparse.

Good old Vade Mecum reveals that in class A2 if we kiss the 14 watts maximum dissipation curve with a loadline drawn from 450v to 100mA
4k5 ohm transformer.

Pick the 250v 40mA operating point, we get 4.5 watts output power in class A2. That is conservative using the +20v to -50 grid lines as a limit. If we allow the voltage to swing right to cut off we can get 6 Watts. Absolutely rediculous efficiency from a 14 watt valve, some of which are the size of a 6sn7.

Drive it with a direct coupled 6as7 CF.

[pre65]

What do you make of the CV2799 (QQV0320 or QQV0320A) double tetrode ?

http://www.r-type.org/exhib/aai0249.htm

It's the one I drive with a chip amp and grounded grid configured as a single triode single ended.

[Paul Barker]

I am not home so can't look but it is a transmitting valve so it won't be in the book. the book only covers "receiving valves".

[Paul Barker]

Pick the 250v 40mA operating point, we get 4.5 watts output power in class A2. That is conservative using the +20v to -50 grid lines as a limit.

OK the elephant in the room is to do the above takes 38 mA of grid current.

To provide that we would have to run the 6as7 direct coupled cathode follower at a quiescent current of double that.

So the thought is, whether it is worth employing a 80mA driver to power an output valve to 4.5 watts?

I suppose the answer has to be, someone has to do it! Unless our Steve or our Phil steps in I'll keep the project in the in tray so it remains a possible project.

There is something I like about the 6V6.

[Paul Barker]

What do you make of the CV2799 (QQV0320 or QQV0320A) double tetrode ?

http://www.r-type.org/exhib/aai0249.htm

It's the one I drive with a chip amp and grounded grid configured as a single triode single ended.

It's not in there Phil.

[Paul Barker]

Pick the 250v 40mA operating point, we get 4.5 watts output power in class A2. That is conservative using the +20v to -50 grid lines as a limit.

OK the elephant in the room is to do the above takes 38 mA of grid current.

To provide that we would have to run the 6as7 direct coupled cathode follower at a quiescent current of double that.

So the thought is, whether it is worth employing a 80mA driver to power an output valve to 4.5 watts?


I suppose the answer has to be, someone has to do it! Unless our Steve or our Phil steps in I'll keep the project in the in tray so it remains a possible project.

There is something I like about the 6V6.

Oh well you can get 4 watts if you bias it at -20v and only go pisitive to +10v and you have to provide 25mA so only need a 50mA driver. that is more realistic.