Plasma Tweeter construction and repair
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Ionovac Replica

I build a DuKane Ionovac Replica out of some parts from the old Tecnac.

The old TECNAC Plasma Tweeter which I bought many years ago was unrepairable because of the resin covered electronic. So I decided to take the horn and the coil to make a Ionovac replica.

The horn has nearly the same dimensions as the Ionovac and my new set replacement quartz cell and electrode for the Ionovac can be tested.


Mechanics

First I had to build the new case, strip the ugly blue paint of the old TECNAC horn and paint it in the brown color as the Dukane was.

The case is build according the original dimensions.

Electronics

The electronic is often the easiest part of building. I use the original plan of the Ionofane because the power supply is the design for the European 230V main voltage. First I wired the RF part of the tweeter with the tube and the coil. I use a EMT block at the front for wireing. 

Power Supply

This is absolutely according the IonoFane plan you see here.

I make a PCB for the power supply this makes it easier to build and the connecting of the transformers and wireing is more solid.


Power supply wireing

Bild in Lightbox öffnen (open image in lightbox). Heater transformer and main input and switch
Bild in Lightbox öffnen (open image in lightbox). modulation transformer and input volume control

These parts are wired to the PCB and the power supply is ready.


The first Test

The speakers worked imidiately. The circuit is reliable and the quartz cell and electrode I made according the old patent from DuKane worked perfect.

Bild in Lightbox öffnen (open image in lightbox). Comparison on the left my replica, on the right the original Ionovac
Bild in Lightbox öffnen (open image in lightbox). here with little monitor speakers the tweeter in the box was disabled
Bild in Lightbox öffnen (open image in lightbox). the replica worked so good that I decided to build matching bass/mid speakers crossover is at 3Khz
Bild in Lightbox öffnen (open image in lightbox). and here in full glory complete tube setup Ionovac replicas with 2A3 paralell push-pull 8 watt amp, bass/midrange with 805 class A, the driver is 300B - 18 watt

Conclusion

This project was fun. The replica worked very well and the little bass-midrange speaker matches the Ionovac replica perfect. The speaker is a Visaton AL130A in a bassreflex enclosure trimed to 45Hz. The reflex port is toward the bottom. This is the reason for the little stand. I am very pleased with this combination. It is ideal for little rooms appr. 25 square meter. There is nothing missing, bass is strong and deap, middle is clear and the plasma tweeter makes the rest.

There is a video about building the tweeter on my Youtube Channel.

Short clip

Here is a short clip to hear the tweeters in action...