Re: VTTC provisional results

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Herwig Roscher by way of Terry Fritz <twftesla-at-uswest-dot-net>" <herwig.roscher-at-gmx.de>


Ed Phillips wrote:

> You could play with increasing the feedback and/or reducing the 
grid bias resistor, but all that might do is just make the tube hotter.

Ed,

Been there, done that :-)   And you are right of course: It made the 
tube hotter. 

> You could use a separate oscillator to drive the tube which drives 
the coil.  That way you could adjust the frequency and leave it 
alone while you try different coupling values and primary tuning.
- I have thought on this as well. From a diathermy machine I 
removed a 150 W triode (together with the powersupply) which I 
could use for this purpose. The main reason I did not build this 
configuration was, that it would not be selfregulating. If the tank 
circuit changed its frequency because of thermal heating or 
introduced capacity (remember that the cap is 700 pF only), the 
oscillator frequency  would be stable, driving the tank with the 
"wrong" frequency. This would cause unwanted "side effects". 
Agree?

> Good luck and keep the reports coming!
- Thank you, Ed. Will do.

Regards,

Herwig