Plasmatweeter

Only the choke with the resistor no capacitor, the impedance should be high for the frequency you like to avoid, that’s all.

Hello,

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Unless i'm mistaken,it's almost linear :
0,15uh 100 Ohms
21mhz: 19,41 Ohms
27mhz: 24,66 Ohms
35mhz: 31,32 Ohms
40mhz: 35,27 Ohms
Value stays low...
 

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Hello sirs,
Thanks for reply and coments.
Done with my phone:

YouTube

Voltage at Anode is too high for the g-807 tube: around 645v.I now replaced the 12ohms resistor by a 20ohm one at the entrance of the voltage doubler,voltage decreased to 630v.
The high voltage value is due to the high capacitance of the doubler's capacitors (almost 800uf mesured for each).600uf should be better.
I'm still waiting a 15k resistor to decrease the voltage at the screen.It's now 265v.It should rate around 250v.
I'm now thinking about Gu50 units who will work with a voltage tripler (almost 900v),and ionophones with g807 and 600v too.
Regards
 
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Hello,

I want to understand something, please...
On many schematics there is no cathod resistor.It means that the tube is 0v biased.
My point of view is ( perhaps i'm wrong ) that the intrance coil is a reactive load ( like a transformer ).
So load line pass though this operating point: Ua,Vg=0
In these case the authorized power is largely exceeded
But it works !
My 807 speaker with no cathod resistor works well.
Stc 807's report indicates 410 ohm for cathode resistor at 100 ma.(-41v for vg)
Dukane Ionovac 6dq6a 120 ohm (it works).
Any review ?

Regards
 
Refurbished my old Tweeters (Frankenplasma's). The power supplies were broken and needed to be replaced. Only used the transformers. The tubes have been replaced in one set by 6HB5 tubes as i have a lot of these (used tubes from my old Acoustat amps).
 

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The power supplies were really old and all electrolytics were dryed out. The tubes are shunt regulators for the screen grids (experimental). I am not sure if i leave them here or find an other solution.
 

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I am happy for now so i leave it as is ( in a later stage i will place the capacitors on the opposite side of the board to keep them away of the heat from the power resistors), now i only need to create a second output on my premap or a XLR splitter as my power amps are dedicated direct drive amps. I will try my headphone amp for these tweeters as not much power is required for these.
 

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