Re: GK71 HFVTTC 30cm Flames
Thomas W, Sun May 27 2012, 10:16PM

wow, thats awsome, i want one so bad D:

Re: GK71 HFVTTC 30cm Flames
RateReducer, Mon May 28 2012, 04:15PM

Thanks, Tom Williamson!
It is not that hard to build one.

Here is a new video getting 30cm flames!
I just increased the topload capacitance and added some chemicals on the breakoutpoint.
The ruler is 30cm in lenght...



I like that tube so much!

Re: GK71 HFVTTC 30cm Flames
Weston, Mon May 28 2012, 11:27PM

So the choke is wound on the same form as the resonator? Does the coupling between them have any effect?

Re: GK71 HFVTTC 30cm Flames
Pinkamena, Tue May 29 2012, 12:41AM

Looks like an expensive and dangerous candle XD

Re: GK71 HFVTTC 30cm Flames
Mads Barnkob, Tue May 29 2012, 05:02AM

Looks good and its a massive output for a tube running with cold plates. I got a good deal of tubes that size, maybe its time for a quick hfvttc as you did :)

Re: GK71 HFVTTC 30cm Flames
RateReducer, Tue May 29 2012, 10:30AM

@Weston: Yes. I don´t know, i never tried to vary the distance between the 2 coils. But i think it does not matter.

@Pinkamena: That is true! xD

@Mads Barnkob: Thanks! :) It stays cold for about 30 seconds or so, than it gets slightly dark red.
"maybe its time for a quick hfvttc as you did :)" Try it! It is very simple and fun!

Greetings

Re: GK71 HFVTTC 30cm Flames
TwirlyWhirly555, Tue May 29 2012, 03:27PM

Very Nice ,as its a pentiode are you running both grids togethere ( G1 / G2 ) ?

Re: GK71 HFVTTC 30cm Flames
RateReducer, Tue May 29 2012, 05:06PM

Thanks.
Grid 1 is for the feedback.
Grid 2 is on supply +. (11,7k)
Grid 3 is on ground.
I could try to connect G1 and G2...

Greetings

Re: GK71 HFVTTC 30cm Flames
zrg, Sun Jun 03 2012, 02:49PM

Well, that's a really well tuned flame discharge generator, I must say.
Being inspired by OP, remade my old GK-71 tweeter. Parameters are quite similar to OP's: ~30 MHz frequency, MOT with full-bridge rectifier and 2uf capacitance, 11k from + to grid 2, 10k from grid 1 to cathode, three power ceramic doorknob USSR caps (K15Y-1) 15 pf each in series, from secondary end to grid 1, as a capacitive feedback.
Plate becomes red-orange after ~20-30 sec run, probably because of no tuning at all

Re: GK71 HFVTTC 30cm Flames
Tetris, Sun Jun 03 2012, 03:19PM

Did you put salt on the electrode? Why is the arc orange? heh. first thing that came to mind was: oh wow this is high current. second thing: if you are amish that inherited a lot of money, and wants to sort of become more with the world, you'd make this. looks like a candle, but much more dangerous and made of plasma.

but that is one badass coil! there is no other way to say it!

Re: GK71 HFVTTC 30cm Flames
RateReducer, Sun Jun 03 2012, 05:53PM

Thanks, zrg! :)
Nice coil. I would like to have ceramic pipes like you use them... The cardboard pipes i use get deformed because of the heat.

Thanks, HighVoltageChick!
No, i do not use salt. It is potassium sodium tartrate. (Stuff to breed crystals xD)

Greetings

Re: GK71 HFVTTC 30cm Flames
zilipoper, Mon Jun 04 2012, 11:20PM

hell fire

Re: GK71 HFVTTC 30cm Flames
RateReducer, Tue Jun 05 2012, 03:51PM

That´s a good comparison!
Even more realistic with sulfur on the breakout point!
Nice bluish flames + smell .

Re: GK71 HFVTTC 30cm Flames
Marko, Sat Jun 16 2012, 02:18PM

Wow, that has to be one insane plasma tweeter. Any attempts at audiomodulation yet?


I'm wondering if this tube is just right for such a tweeter because it's rated for such a low frequency (20Mhz), which probably means it has quite significant output capacitance which helps loading the coil.


Also, how long are the flames without any dopings on the breakout point?


Marko

Re: GK71 HFVTTC 30cm Flames
PhilGood, Sat Jun 16 2012, 05:34PM

Really amazing, congrats !

I gotta build one of these

Could you please share schematics ?

Re: GK71 HFVTTC 30cm Flames
RateReducer, Tue Jun 19 2012, 05:09AM

@Marko: Thanks. Yes i tried to modulate it with a transformer + amplifier... It worked but not very loud. You can find a video on my YT channel.
I am currently working on another tweeter with audio modulation. The flames are about 20cm max. without dopings.

@PhilGood: Thanks. It is just the basic tweeter circuit. You can find many of the in the net. I already posted the grid configuration.
If you have any questions - message ;)

Greetings

Re: GK71 HFVTTC 30cm Flames
Thomas W, Tue Jun 19 2012, 06:16AM

ive ordered my first tube :D

Re: GK71 HFVTTC 30cm Flames
RateReducer, Tue Jun 19 2012, 09:35AM

GK71?

Re: GK71 HFVTTC 30cm Flames
Dr. Dark Current, Tue Jun 19 2012, 09:52AM

Sorry to jump in, I've done some measurements on the GK 71 in the past and it absolutely needs forced air cooling at full plate dissipation, and the plate is not supposed to get red. So if you want your tube to last, direct some air flow onto it and don't let the plate get red.

Re: GK71 HFVTTC 30cm Flames
Thomas W, Tue Jun 19 2012, 03:17PM

indeed it is the GK71, this is my first valve project and i have no clue what values i should use for resistors, capacitors and types ect D:
i have heard that valves are rather forgiving so.... c:

Re: GK71 HFVTTC 30cm Flames
RateReducer, Tue Jun 19 2012, 05:46PM

Thanks for the info Dr. Dark Current!
My tube does not get red