Quote:
Originally Posted by Max
Welll... I must say that in some applications tubes are fairly better still today.
The problem is that semiconductors technology never really solved that issue of stability...
As an example... I made many years ago an oscillator for MD using common fets... I made everything absolutely by the book... considered controlling the current and making feedbacks , but , at the end, I tested the oscillator under various conditions and found that was absolutely instable vs temperature, no matter compensation strategies I tested (many).
I've then redesigned using small tubes , 6.3V powered and got perfect , stable sinus , no matter if I also swing an hairdryer near the osc module...
The MD was rock steady, then I learnt that for some stuff... better using old tubes than newer stuff.
About stability, experience say me that mosfets are good... but tubes are BETTER. 
Kind regards,
Max |
I'm planning first stage only by nuvistor tube, because the first stage is the most important. Nuvistor is very small, light, but consumption is like a common tube, filament 6 V. For filament I need batteries appart.
Another candidate is 1S5 tube, because this need in filament only 1.4 V.