Re: VTTC output

["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>


David Trimmell wrote:

>>  to drive it in A mode?
> Very little DC current would flow, around 10 to 20 mA.

David,

So, that's the way to go.

>> Where should I pick the modulated signal?
> Not to sure of what you mean.
- In order to *measure* the audio response you 
would need a signal to scope it. As I've 
connected a 5 Ohm resistor between the base of 
the secondary and rf ground I could use the 
voltage drop for measurements. Do you think 
that's a good idea? Where did you pick a signal?

> Preliminary testing (low audio power untill I get the amp working 
corectly) does verify that the spark has a 
harder time reproducing low frequency 
signals(<1000-500Hz) without distortion. This I 
need to do more work on though...
- But you are far ahead as I'm about maxing out 
the (unmodulated) output power still. 

> just need a functional Audio Amp!
- It's on my shopping list.

> Really, one does not need a very big spark, to get decent Audio.
- For what audio output power should I aim 
taking into consideration the output power of my 
system?

> Herwig, do have Schematics of your VTTC?
- Unfortunately not in a form I could send to 
you. But the circuit is easy to decribe (please 
use fixed font): 

plate----tank circuit----*----- + 10 kVdc
                         |
                    10 nF/20 kV     
                         |
                       ground

screen grid------*------*-----*----- 0 to 2 kVdc
                 |      |     |
               spark  30 nF/ MOV
                gap   30 kV  1360 V              
                 |      |     |      
              ground ground ground 

control--*-- 25 Ohm/--grid--*--mA--*-- to "bias" 
grid     |   5 W      coil  |      |             
         |                  |      |
        OV              30 kOhm/   |
         |              20 W       |             
         |                  |      |
         a                  |      |
         D                  |    3.7 nF/
         |                 SW    5 kV 
         |                  |      |             
       ground            ground  ground          
            

OVP = gasfilled over voltage protector
D   = fast 30 A diode
SW  = switch, normally closed
mA  = Ameter

"bias"--a diode--10 mH--30 kOhm-- 0 to - 1000 Vdc
                        /20 W
 
If you need further information, just drop me a 
line.


Regards,
 
Herwig