Need Help Identifying these TUBES

[ServinginEcuador]

Guru,

Man, I got everything messed up. I guess that's what happens when you're replying to 10 PMs in under an hour.

OK, the 12AX7 vs EL81 issue: DON'T SWAP THEM AGAIN!! Here's the info on the 12AX7 tube pinout:

1&6: anodes
2&7 grids
3&8: cathode (I figured out what K meant finally!)
4&5 are heaters
9 is the heater tap

This is NOT a good idea to drop an EL81 into the place of a 12AX7. The 12AX? series are all dual triode tubes, meaing they each contain two identical halves, as seen by the pinouts, but the EL81 is not.

PLEASE, don't plug these in again!

 

[braillediver]

Here are a few tubes to consider.

12AX7
12AX7A, 12AX7WA, 12DF7, 12DT7, 7025, 7025A, 12AD7*, 12AU7§, 12AU7A§, 12BZ7*, 12DM7*, 5751*, 5751WA*, 6057, 6681, 7494, 7729

12AU7
12AU7A, 12AU7W, 12AU7WA, 12AX7§, 12AX7A§, 5814*, 5814A, 5814WA*, 5963, 6067, 6189, 6680, 7316, 7489, 7730

12AT7
12AT7WA, 12AT7WB, 6060, 6201, 6211, 6671, 6679, 7492, 7728, A2900, 12AZ7*, 12AZ7A*

EL84 = 6BQ5 = 7189
I believe there's no problem using a 7189 in an EL84 position but an EL84 shouldn't be used in a 7189 position.


Mitch

 

[ServinginEcuador]

Quote:

Originally posted by braillediver I beleive there's no problem using a 7189 in an EL84 position but an EL84 shouldn't be used in a 7189 position.

Max anode voltage and grid voltage on an EL84 is 300v. The 7189 can go up to 400v on the anode, and the same 300v on the grid. This is some good advice Mitch.

 

[gsferrari]

Woah...

What is the 7189? Is one of these tubes a 7189 ??

Ok we know the Telefunken EC-81 is a signal tube

The Tesla and the strange tube are still mysteries...

The EL-42's are Pre-Amps - what the heck does that mean? Are they power tubes??


What I want to know is, Can I build an MG Head "LIKE" amp with the two EL-42's and the EC-81 or the Tesla??

 

[gsferrari]

http://tdsl.duncanamps.com/show.php?des=EL42

http://w1.871.telia.com/~u87127080/pentodl/el42.htm

Wattage output = 6W max!! This thing in a pair can drive a AKG K1000 ??

??

It is 225V so I will need to use a transformer to step up the voltage in whatever I circuit I plan to use this tube...

Am I on the right track??

 

[ServinginEcuador]

Guru,

None of your tubes are 7189s.

A preamp tubes is what they call a small signal tube like the 12A?7 series of tubes. The EL84 is a power tube.

Building an amp with those tubes is feasable, but will be difficult. The reason I think this is because no one does. The tubes that are easy to pair up and make work together have been tried and proven to work. Lots of people use 12a?7 tubes along with the EL84 or 6SN7. It has to do sometimes with gain, voltages, impedance matching, and other factors I don't even know about.

Here's some geeky info on the EC81 tube, which is an ultra-high frequency oscillator tube:
http://www.wps.com/archives/tube-dat...-CC-363/24.JPG

http://www.mif.pg.gda.pl/homepages/f...009/e/EC81.pdf

I'll have more for you in a little bit. Just keep asking questions and I'll see what I can find out for you.

 

[gsferrari]

Brailledriver might be right...this looks like a Magic Eye but AFAIK it used to glow ORANGE but my memory could be fading...


http://w1.871.telia.com/~u87149908/eyes/index.htm

 

[gsferrari]

http://tdsl.duncanamps.com/link.php?target=C82553DA

 

[gsferrari]

http://tdsl.duncanamps.com/show.php?des=ECC81


Data Sheets :-
------------------------
http://tdsl.duncanamps.com/dcigna/tu...rex/at7-1h.gif
http://tdsl.duncanamps.com/dcigna/tu...rex/at7-2h.gif
http://tdsl.duncanamps.com/dcigna/tu...rex/at7-3h.gif
http://tdsl.duncanamps.com/dcigna/tu...rex/at7-4h.gif

Looks like this is a VHF/RF device...

Is it part of a tuner...but AFAIK the Grunding player didnt have a tuner...




DOUG - As far as this article is concerned :-

http://www.wps.com/archives/tube-dat...-CC-363/21.JPG

The ECC81 is a Dual Triode blah! So isnt it just like the 12AX7 ??
It is a low noise voltage amplifier...so is this similar to the function of the 12AX7 in the MG Head??

 

[gsferrari]

OK I understand what mu is - Myu

Its the gain...the EL-42 has a gain of 288 - WOW!

More ECC81 info :-

http://tdsl.duncanamps.com/show.php?des=ECC81

 

[Rob N]

The first tube you listed is definitely a magic eye tube,looks very much like an EM81

See here for more

http://w1.871.telia.com/~u87149908/eyes/em81.htm

 

[gsferrari]

Can someone think of a way to put these tubes to good use? I am thinking of a small amplifier with the EL-42's and the ECC 81.
I could also use the Magic Eye as a volume indicator

Can someone identify the Tesla Tube!!!