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Registered Member #4603
Joined: Wed Apr 25 2012, 07:33PM
Location: Austria
Posts: 159
Today i was bored. So i rebuild my GK71 tweeter. New secondary has 14 turns of 2mm enameled wire on a 55mm cardboard pipe. Somewhere between 20 and 30Mhz. The choke has the same dimensions. I used flat copper for the Anode, the ground connection an the feedback. Power supply is a MOT with bridge rectifier + some microwave caps.
Registered Member #4603
Joined: Wed Apr 25 2012, 07:33PM
Location: Austria
Posts: 159
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...
Registered Member #1403
Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968
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 :)
Registered Member #4603
Joined: Wed Apr 25 2012, 07:33PM
Location: Austria
Posts: 159
@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!
Registered Member #4762
Joined: Sun May 06 2012, 05:59PM
Location: Russia
Posts: 93
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
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