el84 question

[menger66]

Can I use pin 1 on a el84 to connect a resistor to pin2 is there a internal connection?

[sluckey]

Pin 1 and pin 2 are internally connected on some old stock and also some new production EL84s. That internal connection would put a short across a component mounted between those pins.

Read this short discussion for more info...

http://el34world.com/Forum/index.php?to ... #msg192609

[Structo]

It seems that the EL84 tube has more pinout differences between OS (old school) tubes and modern designs, more so than their Octal USA cousins.

Then you have the Russian versions tubes that vary in specs and pinouts.
Think about the Cold War and how it affected tube production.

The free world made tubes with standardized designations for each tube, so you could buy different brands of tubes of the same type, each with their own take on the tube.
Such as RCA, GE, Sylvania (which means "forest land"),Raytheon, Tung Sol, etc.

The USSR made their own vacuum tube designations roughly based on American designs, no doubt a result from espionage, are in Cyrillic which is hard for most non Russian civilians to interpret.

And as vintage tubes become more and more scarce, we will have to source these tubes from manufacturers that may not follow technical guidelines (data sheets) in the tubes they are trying to replicate.

Due to cost, materials and environmental conditions, most Western countries cannot mass produce vacuum tubes any longer.
Which puts the burden on the East to produce these as they become more involved in the global market.

Love to hear an interview with Mike Matthews, owner of Electro-Harmonix, that produces vacuum tubes in Russia.

[gktamps]

Another caution: if you sub with 7189 for their higher voltage handling and more robust construction, pin 1 isn't connected internally, but if you use a 7189a version, it is connected to pin 2 internally.

I learned about this when rebuilding an old Magnatone that was originally set up for 7189 tubes, and had a connection jumpered on pin 1. Since I was replacing those tubes with EL84s, I had to free up pin 1, since so many EL84s have an internal connection.

Here's what someone else has to say about this:
http://www.bustedgear.com/res_Tube_7189.htm

Cheers,

Greg