811a Vacuume Tube tesla coil

[DashApple]

Hey ,

Thought i would post my second tesla coil i made ,

Specs are :

Tube : 811a

Primary is 15 turns and feedback is 16 Turns

Secondary is 1" x 6" with 5.5" worth of windings on , topload is a HDD platter .

GrideLeek Resistor is 5K Ohm , Grid Capacitor is 1nF

Tank Capacitor is 750 somthing pF @ 30kv , power supply is halfwave 2Kv from MOT ,

The Coil in the video 811a vacuume tube tesla coil - YouTube Is running as close to max power befor the anode becoms red , its barly just of starting to redden , so its happy to run like that no problem , i get 3 Inch arcs to air and under full power ( in picture ) i get just over 4 inch arcs that are abit thicker too . its pritty colse to resonance .

All the best

Ion .

 

[Sigurthr]

Very awesome~!

 

[DashApple]

Very awesome~!

Thanks , it does 5" arcs at full power now

 

[Hemlock_Mike]

As long as you keep the tube vertical, the grids won't sag into the fillament ---- I've been there :-(. There was also a tube UV101A which is the same tube but more robust.
HMike

 

[GBD]

As long as you keep the tube vertical, the grids won't sag into the fillament ---- I've been there :-(. There was also a tube UV101A which is the same tube but more robust.
HMike

I won't worry about the tube sagging if run horrizontal, 811As can do so. (you must note the orientation of the pins though, else it will sag. (see the datasheet for that orientation, I can't remember off hand)

This applies to old RCA 811A. The modern chinese counterparts are complete shit and won't survive.

Nice coil, those are pretty nice streamers off a single 811.

 

[Hemlock_Mike]

GBD ---
You must be an old fart like me to know this ....
My killowatt linear amp which I built in 1966 had 4 of
these tubes. I mounted them at 45 deg in a Collins
surplus cabinet. They looked real good but I blew
two into fragments when the sag hit........
The UV101A's didn't have the problem.
My dad didn't like shucking out $12 for new tubes !!!!!
HMike

I need an 807 about now! If you know what this means,
you're about my age!!! WA0BMP

 

[GBD]

I'm 18 lol .. I wasn't even alive back then.

Majority of the old tubes are designed either for horizontal or vertical operation (more the first then the second). I gather some tubes can do funny angles even if not mentioned in the datasheet. what I was mostly pointing out that the modern china tubes are of poor build quality, thier operating hours are much shorter, greater DOA rates, and pretty much total failiure in any position other then vertical with the tubes I had.

as per horizontal when it isn't specified, there are a few ways go about it.

Take for instance the 811 again, or other tubes with a cross-grid design (grid is wound with a flat plane across the filaments, and a narrow plane, all that is hidden behind the plate.)

positioning this plane so it sits vertical relative to the tube's position will allow you to place it at some wierd angles without failiure, going 90 degrees the other way and you risk sagging it.
(the angle refers to the tube's orientation, this is all while the tube lays horrizontal)

Some really high power transmission tubes (GU-series and others, russian and RCA, other 1KW plate dissapation) are so solidly built its pretty hard to wreck them from abuse, forget thier position.

 

[Hemlock_Mike]

OOPS -- You are to young to know about getting
a cold 807!!!!
HMike

 

[GBD]

Too young? 18 is the drinking age here.

 

[Hemlock_Mike]

GBD --
You know about a cold 807 !!! LOL
You must have some real oldtimers
instructing you! 807 , 808, 811 and 813 tubes ---
Good night -- HMike

 

[jeffreythe00]

Nice VTTC! +Rep!

It makes me want to start building my VTTC!

 

[Hemlock_Mike]

Few here will ever experience the awsomness of high
power transmitting tubes glowing orange on the anodes.
A pair of 4-1000A tubes at full PP power is a sight to
behold !!!!
HMike

 

[Tech_Junkie]

I have a collection of around 300 old vacuum tubes. I gotta go through them and see if I have any of these.

 

[DashApple]

Thanks for the replies , Yeah the 811 can run on its side with the heater/cathode / grid in the right orentation ,

There is a 572B tube aswell , 225 Watts dissapation , it was a drop in tube for the 811a Shame they are kinda expensive now . I Need a GU81M

jeffreythe00 - Cheers , good luck on your build , what capacitors for the tank will you use , and tube ?

GBD - thanks , im quite happy with streamer lengh on full power i get 5" arcs and 3" arcs on medium power for long runs , im hoping to get a lerger tube soon to make a larger VTTC once this one is boxed up and i may add a staccato too .


New video

http://www.youtube.com/watch?v=-gT_V3wWaKY&list=UUvjDVNxRU2DInDMQQw_iYJA&index=2&feature=plcp

All the best

Ion

 

[Sigurthr]

Can you post a schematic for your build please? I'd like to build one of these one day.

 

[cheech226]

@ HM
oh i remember the days/nites shooting skip in the 70's with my old executive tube mobile cb. i had a supermag 5/8 wave on the roof and we were near the high elevation in our county. i talked almost everywhere with just the 10w i was getting with just the executive. and with my beam and a d104 mike and my 500w linear i didn't need skip. kept my room warm too during cold pa winters.
unit 226 se pennsylvania how 'bout it skipland skipland skipland....