2 Pin VS 3 Pin Gas Discharge Tubes

[amdx]

I'm looking at Gas discharge tubes, I see 3 pin and 2 pin, but I don't
find any schematic about how to connect them.
My basic use is across a resistor at the end of a antenna wire or
across a feed line transformer. It seems obvious the two tube is
applicable, but how would I use a 3 wire tube.
Where does the 3rd pin go?

Mikek

I found 3 pin at surplus at a very cheap price.

 

[Mike]

In article <qqhmq0$arg$1@dont-email.me>, amdx <nojunk@knology.net> wrote:

I'm looking at Gas discharge tubes, I see 3 pin and 2 pin, but I don't
find any schematic about how to connect them.
My basic use is across a resistor at the end of a antenna wire or
across a feed line transformer. It seems obvious the two tube is
applicable, but how would I use a 3 wire tube.
Where does the 3rd pin go?

I think the 3 pin ones are used in telephone circuits, the middle
leg is earthed, and the outer two legs go to the A and B wires of
the pair (neither of which is directly grounded in normal use). For
balanced circuits and similar.

The 2 pin ones are more obviously one end grounded, one end to the
(single) line you are protecting, in an unbalanced circuit.

--
--------------------------------------+------------------------------------
Mike Brown: mjb[-at-]signal11.org.uk | http://www.signal11.org.uk

 

[Jasen Betts]

On 2019-11-13, amdx <nojunk@knology.net> wrote:

I'm looking at Gas discharge tubes, I see 3 pin and 2 pin, but I don't
find any schematic about how to connect them.
My basic use is across a resistor at the end of a antenna wire or
across a feed line transformer. It seems obvious the two tube is
applicable, but how would I use a 3 wire tube.
Where does the 3rd pin go?

Mikek

I found 3 pin at surplus at a very cheap price.

Three pins is for balanced lines etc. ground the middle pin.

for using three as two either parallel the ends or just use one end
and middle.

--
When I tried casting out nines I made a hash of it.

 

[amdx]

On 11/13/2019 2:39 PM, Jasen Betts wrote:

On 2019-11-13, amdx <nojunk@knology.net> wrote:
I'm looking at Gas discharge tubes, I see 3 pin and 2 pin, but I don't
find any schematic about how to connect them.
My basic use is across a resistor at the end of a antenna wire or
across a feed line transformer. It seems obvious the two tube is
applicable, but how would I use a 3 wire tube.
Where does the 3rd pin go?

Mikek

I found 3 pin at surplus at a very cheap price.

Three pins is for balanced lines etc. ground the middle pin.

for using three as two either parallel the ends or just use one end
and middle.

Great!
Thanks, Mikek

 

[amdx]

On 11/13/2019 1:50 PM, amdx wrote:

I'm looking at Gas discharge tubes, I see 3 pin and 2 pin, but I don't
find any schematic about how to connect them.
 My basic use is across a resistor at the end of a antenna wire or
across a feed line transformer. It seems obvious the two tube is
applicable, but how would I use a 3 wire tube.
 Where does the 3rd pin go?

                     Mikek

I found 3 pin at surplus at a very cheap price.

Following up on Mike's response. My computer didn't display the text.
I used Google groups to see what you said.

I think the 3 pin ones are used in telephone circuits, the middle
leg is earthed, and the outer two legs go to the A and B wires of
the pair (neither of which is directly grounded in normal use). For
balanced circuits and similar.

The 2 pin ones are more obviously one end grounded, one end to the
(single) line you are protecting, in an unbalanced circuit.

So, Is the 3 pin tube basically two-2 pins tubes wired together, using
the center connection going to ground?

If Yes, Can I ground the center pin and tie the two outer pins together
and possibly get two strikes instead of one. I'm assuming they fault
open. Lightning protection on a long wire.
I'm hoping to protect a Vactrol an amplifier input. Not confident
about protecting the amp input.

Mikek

 

[Mike]

In article <qqhr42$6b9$1@dont-email.me>, amdx <nojunk@knology.net> wrote:

I think the 3 pin ones are used in telephone circuits, the middle
leg is earthed, and the outer two legs go to the A and B wires of
the pair (neither of which is directly grounded in normal use). For
balanced circuits and similar.

So, Is the 3 pin tube basically two-2 pins tubes wired together, using
the center connection going to ground?

Pretty much, yes. I'm not sure if it is two separate gas-filled
spaces either side, or one continuous one. The glass ones glow
a pretty orange or purple colour when activated, whereas the 3-legged
ones I've got are all ceramic (solid) body, so hard to tell internally.

If Yes, Can I ground the center pin and tie the two outer pins together
and possibly get two strikes instead of one.

I can't see why not. The voltage trip would remain the same, you might
get a bit of redundancy there

--
--------------------------------------+------------------------------------
Mike Brown: mjb[-at-]signal11.org.uk | http://www.signal11.org.uk

 

[amdx]

On 11/14/2019 9:50 AM, Bert Hickman wrote:

Mike wrote:
In article <qqhr42$6b9$1@dont-email.me>, amdx  <nojunk@knology.net
wrote:

I think the 3 pin ones are used in telephone circuits, the middle
leg is earthed, and the outer two legs go to the A and B wires of
the pair (neither of which is directly grounded in normal use). For
balanced circuits and similar.

  So, Is the 3 pin tube basically two-2 pins tubes wired together, using
the center connection going to ground?

Pretty much, yes. I'm not sure if it is two separate gas-filled
spaces either side, or one continuous one. The glass ones glow
a pretty orange or purple colour when activated, whereas the 3-legged
ones I've got are all ceramic (solid) body, so hard to tell internally.

If Yes,  Can I ground the center pin and tie the two outer pins together
and possibly get two strikes instead of one.

I can't see why not. The voltage trip would remain the same, you might
get a bit of redundancy there


The two gaps will always have slightly different breakdown voltages.

If the outer pins are connected together, only the gap with the lowest
breakdown voltage will fire. Once this gap begins to conduct, the
negative resistance characteristic of the resulting spark/arc will cause
rapid voltage collapse, preventing the other gap from triggering.

That's why I thought I cold get two strikes out of a 3 pin unit.
By strikes, I mean lightning that takes out my termination resistor.

Mikek

 

[Bert Hickman]

Mike wrote:

In article <qqhr42$6b9$1@dont-email.me>, amdx <nojunk@knology.net> wrote:

I think the 3 pin ones are used in telephone circuits, the middle
leg is earthed, and the outer two legs go to the A and B wires of
the pair (neither of which is directly grounded in normal use). For
balanced circuits and similar.

So, Is the 3 pin tube basically two-2 pins tubes wired together, using
the center connection going to ground?

Pretty much, yes. I'm not sure if it is two separate gas-filled
spaces either side, or one continuous one. The glass ones glow
a pretty orange or purple colour when activated, whereas the 3-legged
ones I've got are all ceramic (solid) body, so hard to tell internally.

If Yes, Can I ground the center pin and tie the two outer pins together
and possibly get two strikes instead of one.

I can't see why not. The voltage trip would remain the same, you might
get a bit of redundancy there

The two gaps will always have slightly different breakdown voltages.

If the outer pins are connected together, only the gap with the lowest
breakdown voltage will fire. Once this gap begins to conduct, the
negative resistance characteristic of the resulting spark/arc will cause
rapid voltage collapse, preventing the other gap from triggering.

 

[Joseph Gwinn]

On Nov 14, 2019, Bert Hickman wrote
(in article<R5mdnSyiZ9Iw6lDAnZ2dnUU7-YnNnZ2d@giganews.com&gt:

Mike wrote:
In article<qqhr42$6b9$1@dont-email.me>, amdx<nojunk@knology.net> wrote:

I think the 3 pin ones are used in telephone circuits, the middle
leg is earthed, and the outer two legs go to the A and B wires of
the pair (neither of which is directly grounded in normal use). For
balanced circuits and similar.

So, Is the 3 pin tube basically two-2 pins tubes wired together, using
the center connection going to ground?

Pretty much, yes. I'm not sure if it is two separate gas-filled
spaces either side, or one continuous one. The glass ones glow
a pretty orange or purple colour when activated, whereas the 3-legged
ones I've got are all ceramic (solid) body, so hard to tell internally.

If Yes, Can I ground the center pin and tie the two outer pins together
and possibly get two strikes instead of one.

I can't see why not. The voltage trip would remain the same, you might
get a bit of redundancy there

The two gaps will always have slightly different breakdown voltages.

If the outer pins are connected together, only the gap with the lowest
breakdown voltage will fire. Once this gap begins to conduct, the
negative resistance characteristic of the resulting spark/arc will cause
rapid voltage collapse, preventing the other gap from triggering.

The three-terminal gas tubes have the center electrode grounded and this
electrode is a metal screen or at least has some holes in it, so ions from an
arc on one side will drift across and cause the other side to break down as
well.

Joe Gwinn